Final Year Project Report.

KYAMBOGO

UNIVERSITY

Faculty of Engineering Department of Civil and Building Engineering

Final Year Project Report

Upgrading Nsambya-Kirombe (Gogonya) Road to a Bituminous Paved Surface

Projects coordinator:

Eng Dr Isaac Mutenyo

Supervisor:

Mr. Francis Eugene Okello

Student:

Norman John Byamukama RegNo: 06/U /190/ECD/GV

Project Report submitted as a partial fulfilment for the award of a bachelor of Engineering in Civil and Building of Kyambogo University. June 2010

Authentication

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©Final Year Individual project, Upgrading Nsambya-Kirombe road to a bituminous paved surface. Kyambogo University, Kampala Uganda 2009/10

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This report is dedicated to my dear Parents Mr & Mrs Kezire.

Authentication

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Authentication Declaration I declare that all the work contained in this report is a true reflection of what transpired during the project process and has not been presented to any institution for the award of a Bachelor’s degree. Signature…………………………

Date……………………….

Norman John Byamukama

Approval This is to certify that Norman John Byamukama (RegNo. 06/U/190/ECD/GV) carried out this project titled “Upgrading Nsambya-Kirombe (Gogonya) road to a bituminous paved surface” under my supervision. Signature.....................................

Date……………………….

Mr. Francis Eugene Okello


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Abstract

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Abstract This report consists of a detailed proposed design for upgrading Nsambya-Kirombe (Gogonya) road to a bituminous paved surface which stretches a distance of 1.135km. The main objective was to a design flexible pavement with respect to the route, geometry, drainage and pavement. This was done by assessing the current traffic using the road, existing geometry, pavement structure and designing an appropriate drainage system. The project road was characterised by a broken back curve, reverse curve and sharp curves, which brought about so many delays. Lab and field tests, surveys, consultations, and observations were some of the methods that were used to collect data. From the results obtained, the Average Daily Traffic was 1116Vehicles/day, Motorcycles taking up the greatest percentage of traffic (43%), the subgrade at section 0+500 was found unsuitable having a CBR of 10%, and most of the curves were substandard having a radius of less than 100m. A trapezoidal channel section, culverts were designed to cater for drainage. A double surface dressing has been proposed with chippings being sprayed at 13.367kg/m2 and 9.548kg/m2 for the first and second layer and binder being sprayed at 1.229kg/m2 and 0.949kg/m2 for first and second layer. The ADT showed that the road was due for upgrading considering the Ministry of Works and transports’ criterion for upgrading a road in an urban setting with more than 300Vehicles/day.A realignment has been proposed with curves having a minimum radius of 100m, continuous maintainace of the drains is necessary so as to prevent silting. Quality control should be ensured for materials in accordance with the specifications as stipulated.


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Acknowledgement

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Acknowledgement My sincere thanks go to all those that have enabled me reach to a successful completion of my Bachelors degree especially My Supervisor Mr Francis Eugene Okello who has guided me professionally and been a great inspiration. Resource persons Mr Mubangizi Jude and Mr Busuulwa Patrick for their technical advice, my parents and family members for their moral and financial support, lastly all my friends and coursemates. May the Almighty God richly bless you.


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Table of contents

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Table of contents Authentication......................................................................................................................ii Abstract ............................................................................................................................. iii Acknowledgement ..............................................................................................................iv List of tables .....................................................................................................................viii List of figures......................................................................................................................ix Acronyms and abbreviations ................................................................................................x List of symbols ...................................................................................................................xi

Chapter one...................................................................................................................1 1.0

Introduction.............................................................................................................1

1.1

Background .............................................................................................................1

1.2

Problem statement ...................................................................................................2

1.3

Main Objective........................................................................................................2

1.4

Specific Objectives..................................................................................................3

1.4.1

Geometric Design....................................................................................................3

1.4.2

Drainage..................................................................................................................3

1.4.3

Pavement Design.....................................................................................................3

1.4.4

Environmental, Impact Assessment .........................................................................3

1.5

Project Scope...........................................................................................................4

1.6

Outline Methodology...............................................................................................4

1.6.1

Data Collection and Classification...........................................................................4

1.6.2

Modeling and Analysis............................................................................................4

1.6.3

Design and Simulation.............................................................................................4

1.6.4

Storage and Retrieval ..............................................................................................5

1.6.5

Publication and Dissemination.................................................................................5

1.7

Justification .............................................................................................................5

1.8

Significance.............................................................................................................5


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Table of contents

vi

Chapter Two................................................................................................................6 2.0

Literature review .....................................................................................................6

2.1

Introduction.............................................................................................................6

2.1.1

Project Description..................................................................................................6

2.1.2

Project Location ......................................................................................................6

2.1.3

Demography............................................................................................................6

2.1.4

Land use..................................................................................................................6

2.1.5

Climate....................................................................................................................7

2.2

Route Selection Process...........................................................................................7

2.3

Geometric Design....................................................................................................8

2.3.1

Geometric design standards .....................................................................................8

2.3.2

Design criteria and control.......................................................................................8

2.4

Pavement Design...................................................................................................29

2.4.1

Introduction...........................................................................................................29

2.5

Drainage design.....................................................................................................47

2.5.1

Introduction...........................................................................................................47

2.5.2

Types of drainage ..................................................................................................47

Chapter Three......................................................................................................55 3.0

Methodology .........................................................................................................55

3.1

General..................................................................................................................55

3.1.1

Data collection and classification...........................................................................55

3.1.2

Modeling and analysis ...........................................................................................57

3.1.3

Simulation and design ...........................................................................................57

3.1.4

Publication and dissemination ...............................................................................58

Chapter Four ........................................................................................................59 4.0

Results and discussion...........................................................................................59

4.1

Traffic ...................................................................................................................59

4.1.1

Horizontal alignment Data.....................................................................................60

4.1.2

Vertial alignment Data...........................................................................................61


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vii 4.2

Drainage Design....................................................................................................62

4.3

Pav ement Design..................................................................................................63

Chapter Five ..........................................................................................................66 5.0

Reflections ............................................................................................................66

Chapter Six..................................................................................................................67 6.0

Conclusions and Reccomendations ........................................................................67

Bibliography ......................................................................................................................69 Appendices ........................................................................................................................70 Appendix A, Analysis and Design......................................................................................71 Appendix B:Tables ............................................................................................................83 Appendix C: Geometric Design tables................................................................................85 Appendix D:Pavement design ............................................................................................95 Appendix E: Drainage Design ............................................................................................96 Appendix E: Financial Documentation.................................................................................100 Appendix E: Appraisals.........................................................................................................107


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List of tables

viii

List of tables Table1.1: Highway Length Statistics ...................................................................................83 Table1.2: On going Projects....................................................................................................84 Table 2.1: Division into road category .................................................................................85 Table 2.2: Division into road class.......................................................................................85 Table 2.3: Design Vehicle Characteristics ...........................................................................85 Table 2.4: Terrain Classification..........................................................................................85 Table 2.5: Design parameters...............................................................................................86 Table 2.6: 30th HV as a fraction of ADT ..............................................................................10 Table 2.7: Conversion into PCUs.........................................................................................11 Table 2.8: Vehicle category description ...............................................................................11 Table 2.9: Minimum radius as recommended by MoW&T……………………………………..21 Table 2.10: Maximum grades..........................................................................................…......24 Table 2.11: Pavement deign life selection ............................................................................36 Table 2.12: surface category ................................................................................................38 Table 2.13: Traffic Categories .............................................................................................38 Table 2.14:Nominal size of Chippings .................................................................................39 Table 2.15: Conditions for determining rate of spread of binder...........................................39 Table 2.16 Properties of unbound materials .........................................................................38 Table 2.17 Grading..............................................................................................................38 Table 2.18 Reccomended Plasticty Charactreristics of Granular subbase .............................39 Table 2.19 Typical PSD for sub base ...................................................................................39 Table 4.1: Circular curve data ................................................................................................60 Table 4.2: Transition curve data...........................................................................................60 Table 4.3: Grade.................................................................................................................61 Table 4.4: Vertical alignment data .......................................................................................61 Table 4.5: Crossectional data ...............................................................................................61


viii

List of figures

ix

List of figures Figure 1.1: Highway location process ..................................................................................85 Figure 2.1: Typical vertical curves.......................................................................................22 Figure 2.3: Sight distance over crest curves .........................................................................25 Figure 2.4: Climbing lane outside ordinary lane...................................................................25 Figure 2.5: Crossectional elements ......................................................................................25 Figure 2.6: Pavement layers.....................................................................................................29


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Acronyms and abbreviations

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Acronyms and abbreviations AADT

Average Annual Daily Traffic

ADT

Average daily Traffic

BS

British Standard

CBR

California Bearing Ratio

MDD

Maximum Dry Density

TRRL

Transport and Road Research Laboratory

TRL

Transport Research Laboratory (UK)

SANRA

South African National Roads Agency

SATCC

Southern Africa Transport and Communications Commission

AADT

Annual Average Daily Traffic

AASHTO

American Association of State Highways and Transportation Officials

ALD

Average Least Dimension

E.S.A

Equivalent Standard Axle

GB3

Granular Base-material type 3

HW

Allowable Headwater depth

LL

Liquid Limit

LS

Linear Shrinkage

M.S.A

Millions of equivalent standard axle

MC

Moisture Content

MDD

Maximum Dry Density

OMC

Optimum Moisture Content

ORN

Overseas Road Note

PI

Plasticity Index

PL

Plastic Limit

GB3

Granular Base-material type 3

UBOS

Uganda Beaura of Statistics

UNRA

Uganda National Roads Authority

NTMP

National Transport Master Plan


x

List of symbols

xi


xi

List of symbols m

Meters

mm

Millimetres

v

velocity

w

weight

Kg

Kilograms

L

Litres

E

Easting

N

Northing

Z

Elevation

Ft

Feet

P

Force

%

Percent

Introduction

1.0

1

Introduction

Transport is very vital for the social, economic and political well being of any country; hence it is of paramount importance. Highway transportation overwhelmingly dominates the transportation of people, accounting for 91% of all personal trips (Wright & Paquette 1979). Planning, design, construction and maintainace of highways depend on highway engineers who must translate the desires of the people. From the recent statistics, the total highway length in the world is14, 662, 278.5 km, United States of America having the largest highway length of 6,406,296 km. Of these, 4,148,395km are paved and 2,257,902km unpaved .India has a total highway length of 3,319,644km, of which 1,517,077km are paved and 1,802,567km unpaved. Uganda among the developing countries has 27,000km of highway length of which 1809km are paved and 25,191km are not paved (CIA, 2008). Details of other countries are shown in Table 1.1, Appendix B. From the statistics the following can be inferred, United States of America, one of the most developed nations has most of its highways are paved compared to others. This indicates that development is directly proportional to paved highway length. 1.1

Background

In Uganda, the road network length was approximately 78,100km in 2008, made up of 10,800km of national roads, 27,500km of district roads, 4,800km of urban roads and 35,000km of community roads (NTMP, 2009).with UNRA now established to maintain and improve national roads, a length of 8-10,000km of district roads is to be defined and transferred to the national network giving a new total length of 20,000km each for national and district networks. Presently, Uganda is investing most of its resources in road construction and maintainace. There are many ongoing projects aimed at up grading gravel roads to bitumen standards these include; Kampala –Mityana road Masaka-Mbarara road and Matugga-Semuto-Kapeeka road. These are funded by European Union (UNRA, 2010).See details of ongoing and intended projects by 2013 in Table 1.2 AppendixB. Nsambya-kirombe road is Located in Makidye division, Kampala district. The road stretches a distance of 1.13 km; it’s a district feeder road that falls under Kampala City Council (KCC).


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Problem statement

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This road was mainly established so as to transport local bricks from Kirombe since it was a place where they were manufactured (MOLG, 2009). Presently the manufacture of bricks has seized and many developments are taking place around the project area. This road connects to the National Medical Stores and other supermarkets in the area. This has increased the level of service on this road that it accommodates an Average Daily Traffic is more than 300vehicles per day. Since the road way was not originally designed, it has a narrow width that cannot offer an adequate two way movement of vehicles bringing about delays, its also dusty, with a poor alignment, drainage system is absent along some sections, riding surface is rough, bringing about discomfort during travel. Funds are being sought to have this road upgraded (MOLG, 2009).see Google earth image in, Figure 1.2 in appendix H. 1.2

Problem statement

Roads deteriorate gradually, they under go either functional deterioration or structural deterioration ,functional deterioration refers to the reduction in riding quality while structural deterioration indicates that the pavement layers lose their bearing capacity (Thagesen, 1996) .Failures on roads occur on the pavement layers and drainage system. In this respect, the project road has no drainage system, has a narrow carriage way width of approximately 4.6m, according to the geometric design manual of Uganda, the minimum carriage width for a Gravel C road like the project road is 5.6 m, Poor alignment such as a sharp curve on section 0+243-0+336 of 50m, the minimum radius for the project road should be 100m.A Steep grade of 10% at section 0+580, maximum grade for the project road should be 9% according to the Uganda road design manual. Undulating surface that causes delays, discomfort and dust pollution amounting to approximately 1.5 kg/m2/yr.The international roughness index ((IRI) for the road is 1617.5m/km. The road is therefore due for upgrading. 1.3

Main Objective

To design a structurally stable flexible pavement with respect to the route, geometry, drainage and pavement with an environment impact assessment report so as to promote adequate, safe, well maintained works, transport infrastructure and service for socialeconomic development of Uganda.


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1.4

Specific Objectives

Based on the recommendations of (TRL, ORN6, 1998) the following specific objectives were arrived at; 1.4.1

Geometric Design

a)

Definition of the basic parameters of road function, traffic flow and terrain type;

b)

On the basis of the above estimates, a design class is selected;

c)

Determination of trial alignment;

d)

Selection of design class standards;

e)

Approach speed estimation;

f)

Economic consequences;

g)

Economic return;

h)

Environmental impacts will be considered.

1.4.2

Drainage

In designing drainage the following will be considered; a)

Hydrology;

b)

Hydraulics;

c)

Hydraulic structures;

d)

Environmental, impacts

1.4.3

Pavement Design

Basing on the recommendations of (TRL ORN 31), the following specific objectives were arrived at; a)

Assess traffic so as to assign a traffic class;

b)

Asses the subgrade strength so as to determine the subgrade class;

c)

Selection of appropriate materials and layer thickness with an economic consideration;

d)

Selection of the pavement structure from the traffic class an subgrade class that will be attained above ;

1.4.4

Environmental impacts will be taken into consideration

Basing on the recommendations of Kiely, 1997, the following components of EIA of a road will be considered. ©Final Year Individual project, Upgrading Nsambya-Kirombe road to a bituminous paved surface. Kyambogo University, Kampala Uganda 2009/10

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Project Scope a)

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A summary of the proposed road developments and of the principal environmental impacts;

b)

General project description and alternatives considered;

c)

A baseline survey of the existing environment;

d)

Assessment of the environmental impacts;

e)

The implications for the land use and development plans for the affected area;

f)

The financial implications;

g)

Mitigation measures proposed to reduce negative impacts;

h)

A synoptic table summarising the individual impacts and costs of alternative considered;

i)

Conclusions

1.5

Project Scope

The project will be limited to the following; geometry, drainage and pavement design accompanied with an environmental impact assessment report and a cost estimate of the project. 1.6

Outline Methodology

This has been broken down into the following main headings; 1.6.1

Data Collection and Classification

Data will be collected as follows; Laboratory and field tests, observations, use of questionnaires, documentated literature and consultations. It will be classified by using qualitative and quantitative methods. 1.6.2

Modeling and Analysis

Modelling will be done by Civil Cad, AutoCAD Land development .Analysis will be done by using programmed excel spread sheets and UK DCP soft ware. 1.6.3

Design and Simulation

Designing will be done using the following standards, Transport Research Laboratory, (TRL), Association of American State Highway and Transportation Officials (AASHTO), South.African.National.Roads.Agency, (SANRA) South. African and


4

Storage and Retrieval

5

Communications Commission (SATCC) and the Uganda Design Manual. While Simulation will be done by Civil Simulate. 1.6.4

Storage and Retrieval

A data base for all information will be created using Microsoft access, folders will be created for all the project work on the computer. A backup of all the information will be created on an external hard disk, Compact Discs, Flash disks and E-mail address. Information will retrieved by printing and keeping hard copies. 1.6.5

Publication and Dissemination

The project report will be published by the Author and then a copy will be forwarded to Kyambogo University, others copies shall be given to Kampala city council and other Public libraries. Soft copies will be converted to PDF, to prevent any distortion of the document. 1.7

Justification

The project road has an average daily traffic (ADT) of more than 300 vehicles per day. The Ministry of Works and Housing criterion for upgrading a road with in an urban setting is when ADT is greater than 300 vehicles/day. Vehicle operating costs will be saved since a smooth riding surface will be realised. Upgrading from a gravel surface to a paved road will be justified principally by savings in vehicle operating costs arising from the smoother running surface, but time savings may also be important (TRL 2005). 1.8

Significance

a) The roadway will be widened to 8.6m hence easy manoeuvring of the vehicles. b) Dust pollution will be cease. c) Employment opportunities will be created for people hence economic development. A bout 50 people will be employed during the construction of the road. d) More traffic will be accommodated because diverted traffic and generated will now use this road because of the improvement of the road. e) Comfort due to a good alignment since gentle curves will be introduced. f) Flooding will be controlled since a drainage system will be put in place. g) Reduced highway user costs through increased speed, lesser delays. Since traffic has been flowing at an average speed of 30km/hr, it will now flow at 50km/hr.this will result into a saving of 0.78 minutes per kilometre.


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Literature review

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2.0 Literature review 2.1

Introduction

2.1.1 Project Description Upgrading is improving the quality of something (Microsoft Corporation, 2008). Upgrading projects aim specifically at providing additional capacity when a road is nearing the end of its design life or because there has been an unforeseen change in use of the road. Typical examples of upgrading projects are the paving of gravel roads, the provision of strengthening overlays for paved roads and the widening of roads (TRL 2005).Factors that influence pavement performance include, initial structural capacity, quality of construction, load magnitude and repetitions, drainage conditions, climate and maintainace policies and practices (O’Flaherty 2002).The appraisal of upgrading projects is similar to that of new projects. In fact most ‘new’ projects are essentially upgrading projects (TRL 2005). This project looks at upgrading the existing gravel road by locating an appropriate alignment, recommending an appropriate drainage system, selecting appropriate materials, recommending appropriate layer thicknesses for structural stability with the necessary geometric and structural design. 2.1.2

Project Location

This project road is located in Greater Kampala Metropolitan Area (GKMA), Kampala district, Makidye division, Nsambya, which is approximately 4.8km south –southwest of the Central business district of Kampala along Ggaba road O

at coordinates of

o

00 17’57”N and 32 35’17” E at an elevation of 4003ft (Wikipedia,2009). It connects Kabega road to Lukuli road. 2.1.3

Demography

Uganda has a population of about 29.6 million (UBOS, 2008). The population is projected to be 49.3million people by 2023. Kampala has population of about 1,420,200 (UBOS, 2008) .The project road serves about 1500 people. 2.1.4

Land use

The main activity in this area is farming especially poultry.


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Climate 2.1.5

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Climate

Kampala is Characterized by Tropical wet and dry seasons because of its altitude having heavy rains from August to December and shorter rains from February to June. April has the heaviest amounts of precipitation of about 175mm /hr, January being the warmest (Wikipedia, 2009).

2.2

Route Selection Process

In the relocation or construction of existing highways and the establishment of new ones, surveys are required for the development of project plans and the estimation of costs. The performance of good surveys requires well trained engineers who have an understanding of design, planning and economic aspects of highway location and who are sensitive to the social and economic impacts of highway development. The work of a highway location may include desk study, reconnaissance survey, preliminary survey and a final location survey. See figure 2.1 in Appendix B. Road location is most easily determined through low cost relatively underdeveloped lands, in such locales basic engineering and construction cost considerations normally dominate analyses once the traffic planning need has been established and accepted also provided that environmental issues are not of major concern. The problems become more complex and non engineering issues become more prominent as a route is sought through well developed lands, and when interactions with existing roads and built up areas have to be taken into account. the problems are normally in and about major urban areas where community aspirations, interactions with existing roads, streets and economic, environmental and planning issues become critical. Thus, whilst ideally a new major road needs to be located where it can best serve the traffic desire lines, be as direct as possible, and maximise its function of allowing convenient free flowing traffic operation at minimum construction, environmental, land, traffic operations and maintainace costs. The project road is already in existence; only the alignment will be studied to see if it’s adequate.


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Geometric Design

2.3

8

Geometric Design

Geometric design is the process whereby the layout of the road in the terrain is designed to meet the needs of the road users. The principal geometric features are the road crosssection, horizontal and vertical alignment. Good geometric design ensures that adequate levels of safety and comfort are provided for drivers for vehicle manoeuvres’ at the design speed, and that the road is designed uniformly and economically, blending harmoniously with the land escape (O’Flaherty, 2002). The use of geometric design standards fulfils three inter related objectives. Firstly, standards are intended to provide minimum levels of safety and comfort for drivers by the provision of adequate sight distances, coefficients of friction and road space for vehicle manoeuvres; secondly, they provide the framework for economic design; and, thirdly, they ensure a consistency of alignment. The design standards adopted must take into account the environmental road conditions, traffic characteristics, and driver behaviour. 2.3.1 Geometric design standards The design standards adopted for this project will be the Ministry of Works, Housing and Communication design manual of 2005, TRL Over Seas Road Notes, SATCC and SANRA.The design will be based on the road category, expected volume and compositions. The restrictions are mainly by the terrain classification and road environment. 2.3.2

Design criteria and control

Highway geometrics are generally affected by so many factors some of which include the following, Design speed and limit, Road function, topography, traffic, capacity, design vehicle, control of access and level of service. a)

Design Speed

The assumed design speed for a highway may be considered as the maximum safe speed that can be maintained over a specified section of highway when conditions are so favourable that the design features govern. The choice of design speed will depend primarily on the terrain and functional class of the highway. Other factors determining the selection of design speed include traffic volume and composition, costs of right of way and construction, and aesthetic considerations (Wright &Paquatte, 1979).


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Road function Design

9

Design speed is used as an index which links road function, traffic flow and terrain to the design parameters of sight distance and curvature to ensure that a driver is presented with a reasonably consistent speed environment. In practice, most roads will only be constrained to minimum parameter values over short sections or on specific geometric elements (TRL, ORN6).For this project a design speed of 50km/hr will adopted as per Table 2.5: Appendix C. b)

Road function Design

h)

Division into road category

The roads in Uganda are divided into the following categories according to their major function within the network; see Appendix C, Table 2.1 .Basing on its function, the project road falls under category C since service is provided to smaller communities.

ii)

Division into road class

The division is governed by the design speed and design traffic (MoWH&C, 1994) See Table 2.2: Appendix C. from the above table, the project road falls under class C Gravel from the existing characteristics of capacity, carriage width and capacity. c)

Topography

The Uganda Road Design Manual (2004) defines the following types of terrain as shown in Table 2.4, Terrain Classification See appendix C, from the description, the project road fall under rolling terrain since it has a traverse slope of approximately 10% which lies between 20% and 5% d)

Capacity

Capacity can be defined as the maximum number of vehicles per unit time that can be handled by a particular roadway component or section under the prevailing conditions. Road capacity information is useful for (i) Transportation planning studies to assess the adequacy or sufficiency of existing road network to service current traffic and to estimate the time in the future when traffic growth may overtake capacity. (ii) It is important in design of road dimensions, number of lanes and minimum length of weaving length; (iii) In traffic operation analysis in improvement of traffic operation (Uganda geometric design manual, 2004) ©Final Year Individual project, Upgrading Nsambya-Kirombe road to a bituminous paved surface. Kyambogo University, Kampala Uganda 2009/10

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Traffic a)

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Level of service

Level of Service expresses the effectiveness of the road in terms of operating conditions. It is a qualitative measure of the effect of traffic flow factors, such as speed and travel time, interruptions, freedom of maneuver, driver comfort and convenience, and indirectly safety and operation costs( (MoW&T, 1994). b)

Traffic

Traffic volume indicates the level of service for which the highway is being planned and directly affects the geometric features such as width, alignment and grades (Kadiyali, 2008). i)

Design hour volume

The unit for measuring traffic on a highway is the Annual Average Daily Traffic volume, abbreviated as (AADT). It is equal to the total annual volume of traffic divided by the number of days in the year. This is not commonly used in geometric design, since it does not represent the variations in traffic during various months of the year, days of the week and hours of the day. It is not economically sound to design a facility to be congest free every hour through the year, however it has been established that each year the traffic volume often reaches that of the 30th heaviest hour, which is the hourly volume exceeded only 29 hours a year. ( (Thagesen, 1996) hence a unit for geometric design is the 30th highest hourly volume abbreviated as 30 HV which is defined as the 30th highest hourly volume during the year (Kadiyali, 2008). DHV = AADT x K Where K is estimated from the ratio of the 30th HV to the AADT from a similar site and is expressed as a fraction of ADT can vary as indicated in the following table. Table 2.6: 30th HV as a fraction of ADT for different traffic Conditions Traffic Condition 30th HV as a fraction of ADT Rural Arterial (average value)

0.15

Rural Arterial (maximum 0.25 Heavily trafficked road under 0.08 – 0.12 Congested urban conditions Normal urban conditions 0.10 – 0.15 Road catering for recreational 0.20 – 0.30 or Other traffic of seasonal Source: Uganda Road Design Manual (2005)

The project road falls under Normal Urban Conditions, thus it has a K value 0.15 which is taken as the average of (0.10 – 0.15) for design purposes.


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Traffic composition

ii)

11

Directional distribution of traffic

Traffic flow figures available are for two way flow, and the directional split ratio is 1:2 and this will be adopted for the project (Kadiyali, 2008). a)

Traffic composition

Traffic composition has a vital effect on capacity and other design considerations. It is customary in this country to express the traffic volume in terms of passenger car units (PCUs), also representative for combined group of medium and heavy goods vehicles and buses. Table 2.7: Conversion into PCU Vehicle Type Passenger cars Light goods vehicle

1

Terrain Rolling PCU 1

Level

Mountainous 1.5

1

1.5

3

Medium goods vehicle*

2.5

5

10

Heavy goods vehicle Buses Motor cycles, Scooters

3.5 2 1

8 4 1

20 6 1.5

Pedal cycles

0.5

0.5

NA

Source: Uganda Road Design Manual, 2005

The following definitions apply to the different vehicle types mentioned in the table. Table 2.8: Vehicle category Descriptions Vehicle Category

Description

Passenger cars

Passenger vehicles with less than nine seats.

Light goods vehicle

Land rovers

Minibuses and goods vehicles Medium goods vehicle Heavy goods vehicle Buses

of less than1500kg un-laden weight with payload capacities less than 760 kg. Maximum gross vehicle weight 8500 kg. Gross vehicle weight greater than 8500 kg. All passenger vehicles larger than minibus

` Source: Uganda Road Design Manual, 2005 iii)

Estimation of traffic flows

a)

Baseline traffic flows (FO)

This is the Average Daily Traffic (ADT) which is defined as the total annual traffic summed for both directions and divided by 365. For this project, the traffic currently using the route was classified into the vehicle categories of cars, light goods vehicles, trucks (heavy goods vehicles) and buses


11

Projected traffic (Fp) b)

12

Projected traffic (Fp)

For this project, time series was used to project traffic growth rates. FP = FO (1+ r)n

… 2.1

Where,

FP = Cumulative number of commercial vehicles after ‘n’ years; FO = Present number of vehicles after the traffic survey;

r = Growth rate of commercial vehicles; n = Number of years of projection

iv)

Design vehicle

The dimensions of the motor vehicle also influence design practice. The physical characteristics of vehicles and the proportions of the various sizes of vehicles using a road are positive controls in design and define several geometric design elements, including intersections, on and off-street parking, site access configurations and specialized applications such as trucking facilities. Therefore, it is necessary to examine all vehicle types, select general class groupings, and establish representatively sized vehicles within each class for design use. Vehicle characteristics affecting design include power to weight ratio, minimum turning radius, and travel path during a turn, vehicle height and width. The main road elements affected are gradient, road widening in horizontal curves and junction design. In the design of road facility the largest design vehicle likely to use that facility with considerable frequency or a design vehicle with special characteristics that must be taken into account in dimensioning the facility is used to determine the design of such critical features as radii at intersections and radii of horizontal curves of roads. For this project the design vehicles DV 5 will be used to control the geometric design. See appendix C,Table: 2.3 for the design vehicles. 2.3.3 Alignment An ideal and most interesting roadway is the one that generally follows the existing natural topography of a country. This is the most economical to construct, but there are certain aspects of design that must be adhered to which may prevent the designer from following this undulating surface without making certain adjustments to the in the vertical and horizontal directions. The designer must produce an alignment in which conditions are consistent. Sudden changes in the alignment should be avoided as much as possible, for example, long tangents should be connected with long sweeping curves, and short curves should not be interspersed with long curves of small curvature. The ©Final Year Individual project, Upgrading Nsambya-Kirombe road to a bituminous paved surface. Kyambogo University, Kampala Uganda 2009/10

12

Horizontal alignment

13

ideal locations are one with consistent alignment where both grade and curvature receive consideration and satisfy limiting criteria. The final alignment will be that in which the best balance between grade and curvature is achieved (Wright & paquatte, 1979). Horizontal and vertical alignment should not be designed independently, they compliment each Other and proper combination of horizontal and vertical alignment, increases road utility and safety, encourages uniform speed, and improves appearance, can almost always be obtained without additional costs. it is further more important that the choice of the standard for the above geometric design elements is balanced to avoid the application of minimum values for one or a few of the elements at a particular location when other elements are considerably above minimum requirements. (Thagesen, 1996) the author intends to

assess the existing alignment and up grade

where necessary. a)

Horizontal alignment

Horizontal alignment of a highway defines its location and orientation in plan view. It consists of a series of intersecting tangents and circular curves, with or without transition curves. (Thagesen, 1996) The design elements of a horizontal alignment are the tangent (straight section), the circular curve, the transition curve (spiral curve) and the super elevation sections. The horizontal alignment should always be designed to the highest standard consistent with the topography and chosen carefully to minimize earthworks. The alignment design should also be aimed at achieving a uniform operating speed. •

Near minimum curves shouldn’t be used at the following locations; On high fill or elevated structures, as the lack of surrounding objects reduces the drivers’ perception of the road alignment.

•

At or near a vertical curve, especially crest curves, as it would be extremely dangerous, in particular at night time.

•

At the end of long tangents or a series of gentle curves; also compound curves, where a sharp curve follows a long flat curve, should be avoided in order not to mislead the driver.

•

At or near intersections and approaches to bridges, in particular approaches to single lane bridges (Thagesen,1996).


13

Horizontal alignment •

14

Long straights should be avoided as they are monotonous for drivers and cause headlight dazzle on straight grades.

i)

General controls for horizontal alignment

The following general controls for horizontal alignment should be kept in view in a sound design practice: •

The alignment should be as directional as possible;

•

The alignment should be consistent with topography and should generally

conform to the natural contours. A line cutting across the contours involves high fills and deep cuts, mars the landscape and is difficult for maintenance; •

The number of curves should, in general, be kept to a minimum;

The alignment should avoid abrupt turns. Winding alignment consisting of short curves should be avoided, since it is the cause of erratic vehicle operation; •

A sharp curve at the end of along tangent is extremely hazardous and should be

avoided. If sharp curvature is unavoidable over a portion of the route selected, it is preferable that this portion of the road be preceded by successive sharper curves. Proper signage, well in advance of a sharp horizontal curve is essential; Short curves giving the appearance of kinks should be avoided, especially for small deflection angles. The curves should be sufficiently long to provide a pleasing appearance and smooth driving on important highways. They should be at least 150m long for a deflection angle of 5 degrees, and the minimum length should be increased by 30m for each 1 degree decrease in the deflection angle; •

For a particular design speed, as large a radius as possible should be adopted. The

minimum radii should be reserved only for the critical locations; •

The use of sharp curves should be avoided on high fills. In the absence of cut

slopes, shrubs, trees, etc., above the roadway, the drivers may have difficulty in estimating the extent of curvature and fail to adjust to the conditions; •

While abrupt reversals in curvature are to be avoided, the use of reverse curves

becomes unavoidable in hilly terrain. When they are provided, adequately long transitional curves should be inserted for super-elevation run-off; •

Curves in the same direction separated by short tangents, say 300m -500m long,

and are called broken-back curves. They should be avoided as they are not pleasing in appearance and are hazardous; •

Compound curves may be used in difficult topography in preference to a broken-

back arrangement, but they should be used only if it is impossible to fit in a single ©Final Year Individual project, Upgrading Nsambya-Kirombe road to a bituminous paved surface. Kyambogo University, Kampala Uganda 2009/10

14

Types of curves

15

circular curve. To ensure safe and smooth transition from curve to curve, the radius of the flatter curve should not be disproportional to the radius of the sharper curve. A ratio of 2:1 or preferably 1.5:1 should be adopted; The horizontal alignment should blend with the vertical harmoniously. General controls for the combination of horizontal and vertical alignments should be followed (Kadiyali, 2008). ii) Super elevation When a fast moving vehicle negotiates a horizontal curve, an outward centrifugal force acts on the vehicle and its lateral stability gets affected. The value of this centrifugal force P in kgs is given as

P=

wv 2 gR

…2.2

Where w the weight of the vehicle and v is the speed in m /s , g = 9.8m / s 2 and R is the radius of the horizontal curve in metres. The centrifugal force acts in the horizontal direction and the mass passes through the centre of gravity of the vehicle. If the value of the centrifugal force is greater than the lateral frictional resistance between wheels and the road surface, skidding of the vehicle may occur and if the vehicle speed is still not reduced the vehicle may topple over. To reduce this tendency of the vehicle skidding, the outer edge of the road pavement is raised with respect to the inner edge, thus tilting the road surface from the outer edge towards the inner edge. This lateral inclination to the road surface is known as super elevation (Singh, 2004). It is common practice to utilize a low maximum rate of super elevation, usually 4 percent. Similarly, either a low maximum rate of super elevation or no super elevation is employed within important intersection areas or where there is a tendency to drive slowly because of turning and crossing movements, warning devices, and signals. Super elevation is a requirement for all standards of roads. (Uganda Road design Manual, 2004) A maximum super elevation of 4% will be employed for the project road. Types of curves i)

Circular curves

Circular curves may be described by giving either the radius or degree of a curve. As a vehicle traverses a circular curve, it is subject to inertial forces which must be balanced by centripetal forces associated with the circular path. For a given radius and


15

Circular curves

16

speed a set of forces is required to keep the vehicle in its path. The radius can be expressed by the formula

R=

V2 127(100e+ f)

…2.3

Where R = Radius of the curve (metres)

e =Crossfall of the road (%) (Is negative for adverse crossfall) f =Coefficient of side (radial) friction force developed between the tyres and road

pavement (Uganda road design manual) According to Kadiyali, (2008), radius is given as R=

V2 225e

…2.4

v = is the design speed e = Super elevation rate

ii)

Transition curves

The characteristic of transition (spiral or clothoid) curve is that it has a constantly changing radius. Transition curves may be inserted between tangents and circular curves to reduce the abrupt introduction of the lateral acceleration. They may also be used to link straights or two circular curves. In practice, drivers employ their own transition on entry to a circular curve and transition curves contribute to the comfort of the driver in only a limited number of situations. However, they also provide convenient sections over which super elevation or pavement widening may be applied, and can improve the appearance of the road by avoiding sharp discontinuities in alignment at the beginning and end of circular curves. For large radius curves the rate of change of lateral acceleration is small and transition curves are not normally required. The Euler spiral, which is also known as the clothoid, is preferred to be used. The radius of clothoid varies from infinity at that tangent end of the spiral to the radius of the circular arc at the circular curve end. By definition the radius at any point of the spiral varies inversely with the distance measured along the spiral. The following equation is used for computing the minimum length of spiral. ©Final Year Individual project, Upgrading Nsambya-Kirombe road to a bituminous paved surface. Kyambogo University, Kampala Uganda 2009/10

16

Re quirements of Transition curves

L=

0.0702V 3 RC

17

…..2.5

Where: L = minimum length of spiral, (m); V = speed, km/h; R = curve radius, (m); and, C = rate of increase of centripetal acceleration, m/s3 MoWT, 2004) .The factor C is an empirical value indicating the comfort and safety involved.

The value C=1 is

acceptable for railroad operation, but values ranging from 1 to 3 have been used for roads. A more practical control for the length of spiral is that in which it equals the length required for super elevation runoff. •

Re quirements of Transition curves

Transition curves are required if the following relationship is fulfilled: R<

V

3

432

…2.6

Where: R = Radius of curve (m); and,

V = Design speed (km/hr) In all other cases where the above is not fulfilled, transition curve is not required. (MoWT, 2004) According to Kadiyali (2000), Length of the transition is given as Ls =

C=

0.0215V

3

c×R

…2.7

80 75 + V

Where V is the design speed in km/hr. The author intends to use this formula according to Kadiyali for designing transition curves.


17

Vertical alignment a)

18

Vertical alignment

The vertical alignment of a road has a strong influence upon the construction cost, the operating cost of vehicles using the road, and the number of accidents. The vertical alignment should provide adequate sight distances over crests and should not present any sudden hidden changes in alignment to the driver. Gradients need to be considered from the standpoint of both length and steepness, and the speed at which heavy vehicles enter the gradient. They should be Chosen such that any marginal increase in construction costs is more than offset by the savings in operating costs of the heavy vehicles ascending them over the project analysis period. Vertical Alignment of a highway deals with its shape in profile. For a roadway with contiguous travel lanes, alignment can be conveniently represented by the centerline of the roadway.The two major aspects of vertical alignment are vertical curvature, which is governed by sight distance and comfort criteria and gradient which is related to vehicle performance and level of service (MoWT, 2004). Vertical curves are required to provide smooth transitions between consecutive straight gradients. The simple parabola is recommended for these. The parabola provides a constant rate of change of curvature and hence acceleration and visibility, along its length and it has the form: g -g r= 2 1 L 2 rx y= + g1x + BVCelevation 2

…2.8

Where r=

Rate of change of grade per section (%)

g1 = Starting grade (%) g2 = Ending grade (%) L=

Length of curve (horizontal distance (m)

y=

Elevation of a point on the curve

x=

Distance in stations from the BVC (beginning of vertical curve) (meters/100)

BVCelevation = Elevation of beginning of the vertical curve EVC = End of the vertical curve ©Final Year Individual project, Upgrading Nsambya-Kirombe road to a bituminous paved surface. Kyambogo University, Kampala Uganda 2009/10

18

Vertical alignment

19

A related formula is: y=

G * L x

2

200  L 

… 2.9

Where y = vertical distance from the tangent to the curve (meters) x = horizontal distance from the start of the vertical curve (meters) G = algebraic difference in gradients (%) L=

length of vertical curve (meters)

The two main requirements in the design and construction of vertical curves are the provision of: adequate visibility, Passenger comfort and safety. In order to provide adequate visibility, oncoming vehicles or any obstructions in the road must be seen clearly and in good time to ensure that vehicles travelling at the design speed can stop or overtake safely. In order to provide passenger comfort, the effect of the radial force on the vehicle traversing a vertical curve must be minimized. In crest curve design, this effect could cause the vehicle to leave the road surface

while in the sag curve the

underside of the vehicle would come into contact with the surface, particularly where the gradients are steep. i)

General Controls for Vertical Curve Alignment

The following general controls for vertical alignment should be kept in view while designing the vertical profile of a highway: •

The grade line selected should be smooth with gradual changes, consistent with the class of highway and terrain. Numerous breaks and short lengths of grades should be avoided;

•

The ‘roller-coaster’ or ‘hidden type’ of profile should be avoided as it is hazardous and aesthetically unpleasant;

•

Undulating grade line, involving substantial lengths of momentum grades, should be appraised for their effect upon traffic operation. Such profiles permit heavy trucks to Operate at higher overall speeds than when an upgrade is not preceded by a down grade, but may encourage excessive speeds of trucks with consequent hazard to traffic;


19

Stopping sight distance

20

A broken-back grade line (two vertical curves in the same direction separated by short Section of tangent grade) should generally be avoided; •

On long continuous grades, it may be preferable to place the steepest grades at the bottom and flatten the grades near the top. Alternatively, long grades may be broken by short intervals of flatter grades;

•

Intersections on grades should be avoided as far as possible. Where unavoidable, the Approach gradients and the gradient through the intersections should be flattened to the Maximum possible extent.

ii)

Sight distance

Safe highways must be designed to give the driver a sufficient distance of clear vision ahead so that he/she can avoid hitting unexpected obstacles and can pass slower vehicles without danger. Sight distance is the length of highway visible ahead to the driver of a vehicle. When this distance is not long enough to permit passing an overtaken vehicle, it is termed stopping sight distance (Wright & paquatte, 1979). •

Stopping sight distance

Minimum distance required for stopping a vehicle travelling at or near the design speed before reaching an object in its path. Minimum stopping sight distance is based upon the sum of two distances (Wright& paquatte, 1979). The distance travelled from the time the object is sighted to the instant that the brakes are applied, and the distance require for stopping the vehicle after the brakes are applied. The first of these two distances is dependant upon the speed of the vehicle and brake reaction time of the operator. The second distance depends upon the speed of the vehicle, condition of brakes, tyres, roadway surface, alignment and grade of the highway. •

Passing sight distance

When the sight distance is long enough to enable a vehicle to overtake and pass another vehicle on a two lane highway without interference from an oncoming vehicle, it is termed passing sight distance (Wright& paquatte, 1979).


20

Crest curves

iii)

21

Vertical curves

A vertical curve provides smooth transition between successive tangent gradients in the road profile. When the algebraic difference of the two gradients is positive the curve is called a crest or summit. When the difference is negative, it’s called sag. As a motorist traverses a vertical curve, a radial force acts on the vehicle and tries to force it away from the centre of curvature and this may give discomfort to the driver. This discomfort may be minimised by restricting the gradients and by using a type and length of vertical curve which allows a radial force to be experienced gradually and uniformly. Sight distance requirements are also aided by use of vertical curves on both crest and sag (O'Flaherty, 2002). Figure 2.2: Typical Vertical curves

Source O’Flaherty, 2002 Table 2.9: Minimum radius as recommended by MoW&T Radius(m)R (R=K*100) Speed(Km/h)

Stopping desirable

minimum

desirale

50

1100

600

11000

5500

80

4500

3000

32000

15000

65000

24000

100 10000 7000 Source, Uganda road design manual, 2004

a)

Overtaking "No overtaking"centreline markings

Crest curves

The sight distance requirements for safety are critical to the design of a crest curve. Thus when calculating the minimum lengths of crest curves, there are two design conditions that have to be considered.


21

Crest curves

22

Sight distance over crest curves when a) S•L and S>L Figure 1.3: Sight Distance over crest curves

Source, O’Flaherty, 2002

For S•L Lmin =

AS 2 2 2h1 )1/2 + (2h2 

…2.10

S>L

2[h1 + h2 ]

2

Lmin = 2S −

A

…2.11

Where h1= Drivers eye height (Usually 1.05m) h2= Object height (usually 0.26m) L = Minimum length of sag curve (m) A = algebraic difference in grades expressed as a decimal. D = vertical clearance (ideally taken as 5.7m) to the critical edge of the Bridge The critical edge is assumed to be directly over the point of intersection of tangents. In practice both equations can be considered valid provided that the critical edge is not more than 60m from the point of intersection [O’Flaherty, 2002]. If h1=1.05m and h2=0.26m then the above equations refer to the safe stopping sight distance (SSD) and become, for SSD•L

Lmin =

AS 2 471

…2.12

FOR SSD>L


22

Crest curves

Lmin = 2S −

471 A

23

…2.13

If h1=h2=1.05m then the equations refer to the full overtaking distance (FOSD), and then, for FOSD•L

Lmin =

AS 2 840

…2.14

For FOSD>L

Lmin = 2S −

840 A

Based on Motorist Comfort The minimum length of vertical sag curve is given by:

Lmin =

V 2A V 2A = 3α 390

…2.15

Where; V = design speed (km/hr), A is the algebraic difference in grade (%), and • = vertical radial acceleration (m/s2) usually taken as 0.3 m/s2 for comfortable design (O’Flaherty, 2002). Sag Curves When a road passes beneath an overpass, the driver’s line of sight may be obstructed by the edge of the bridge. Then the minimum length of a sag curve which meets minimum stopping sight distance requirements is given by Lmin =

S 2A 8D − 8(h1 + h2    When SSD•L 2

8D − 8( h1 + h2 )  2  Lmin = 2S −  When SSD•L A

…2.16

…2.17

if eye height h1=1.05m and object height h2 =0.26mm the above equations becomes


23

Climbing lanes Lmin =

S 2A [800D − 524]

Lmin = 2S −

When SSD•L

24

…2.18

[800D − 524] A

When SSD>L

…2.19

L= minimum length of the sag curve (m) S= minimum stopping sight distance (m) and A is algebraic difference in grades expressed in decimal form, and D=vertical clearance (ideally, taken as 5.7m to the critical length of the over bridge. (O'Flaherty, 2002) iv)

Gradients

The rate of rise or fall of road surface along its length with respect to the horizontal distance is termed as gradient. it may also be defined as a longitudinal slope of a road pavement a rising grate is denoted by + sign while a falling gradient is denoted –sign Grade of a road should not be very steep, steep grades are not only difficult to climb but also increase operational costs of vehicles. (Singh, 2004) In the establishment of a grade, an ideal situation is one in which the cut is balanced against the fill without a great deal of borrow or an excess cut to be wasted. (Wright & paquatte, 1979) A minimum gradient of 0.5 is needed for longitudinal drainage (O'Flaherty, 2002). Table 2.10: Maximum grades Maximum Grade (%) Speed (km/hr) Flat Rolling Mountainous 50 6-8 7-9 9-10 80 4-6 5-7 7-9 100 3-5 4-6 6-8 Source: Uganda Road Design Manual (2004)

For the project road a maximum grade of 9% will be considered since it is a rolling terrain. •

Climbing lanes

The maximum gradient is not in itself a complete design control, and an extra climbing lane is often provided on long uphill climbs. the addition of a climbing lane is normally considered when the combination of hill severity and traffic volumes and composition is such that the operational benefits achieved are greater than the additional cost of providing the extra lane (O'Flaherty, 2002) These improve overtaking opportunities,


24

Cross-sectional Elements

25

capacity and safety because of the presence of a steep uphill gradient. It is inserted into the carriageway by means of entry and exit tapers to the left of the continuous lane so that slow moving vehicles have to merge into the faster traffic at the termination point. An overtaking lane serves the same objectives without a steep gradient. Climbing lanes should be considered if the design truck speed decreases more than 20 km/h under the truck speed limit, normally 80 km/h in rural conditions (MoWH&C, 2004). Figure 2.4: Climbing lane outside the ordinary lane

Source, Uganda Road Design Manual, 2004

b)

Cross-sectional Elements

These are elements of a roadway which form its effective width. These include a carriage way, central reservation and the side slopes of cuttings and embankments. Figure 2.5: Cross sectional elements for a single carriage way

Carriage way Shoulder

Traffic lane Camber

Traffic lane

Shoulder

Camber

Embarkment

Foreslope cut

Backslpoe

Road reserve

Source, Uganda road design manual, 2004

i)

Road reserve

The road reserve or right-of-way width is the width of land secured and preserved in public interest for road development purposes. The road reserve should be adequate to accommodate all the elements that make up the cross-section of the highway and may reasonably provide for future development. Such as upgrading of the alignment. The right of way must include the acquisition of land for short cuts and path of pedestrians,(TRL,1993) ,for the project road, a road reserve of 7.5m will be considered due to a narrow existing carriage way, it would cost around 20 billion to compensate people e along the road. ii)

Carriage way width


25

Kerbs

26

The term “carriageway” is used here to cover the traffic lanes, any auxiliary lanes, and the shoulders (MoWH&C, 2004). The width of traffic lanes governs the safety and convenience of traffic and has a profound influence on the capacity of a road. Factors that influence the width of the carriage way is: design volume, vehicle dimensions, design speeds and road classification. Internationally, it is generally accepted that lane widths should normally be at least 3.5m, although narrower lanes are often used for economic or environmental reasons on both rural and urban roads. However, increasing the lane width up to 3.65m on two lane two way rural roads decreases accident rates (O’Flaherty, 2002). For the project road a lane width of 2.8m will be considered from classification of a gravel C, see Appendix C, Table 2.5. iii)

Central reservation strip

A central reservation strip is the longitudinal space separating dual carriageways. The functions of the median strip are: To separate high speed opposing traffic, there by lessening the chances of head-on collisions, Provides a safe waiting place for pedestrians crossing the high speed carriage way and provide space for road furniture and markings. For the project road, a central reservation will not be considered because of the existing carriageway width. iv)

Shoulders

A shoulder is that surfaced clear portion of the roadway cross-section immediately adjacent to the carriage edge. Shoulders have several numbers of purposes such s refuge for vehicles forced to make emergency stops, (O'Flaherty, 2002)

An area out of the

Lateral support of the roadway structure. In addition, shoulders support use of the road by other modes of transport, for example cyclists and pedestrians (SANRA,..) a slope of the shoulder should be greater than the that of the pavement for drainage purposes (Wright &Paquatte, 1979) for the project road a shoulder of 1.5m will be used as in table2….as stipulated in the Uganda road design manual v)

Kerbs

A kerb is a vertical or sloping member along the edge of a pavement or shoulder, forming part of gutter, strengthening or protecting the edge, and clearly defining the edge to vehicle operators. Its functions are: they define the edge of traffic lanes, traffic islands and footways – during both day and night (they reflect vehicle headlights)


26

Kerbs

27

• They support pavements and island structures so that edge break-up is avoided; •

They protect adjacent areas from encroachment by vehicles; • They assist in drainage of the carriageway (MoW&T, 2004). vii)

Camber

Camber, is a term used to define convexity of the carriageway cross section. Its purpose is to drain surface water from the road and avoid ponding in the surface deformations on the carriage way (O'Flaherty, 2002). A camber of 2.5% will be used for the project road. Across fall should be sufficient to provide adequate surface drainage whilst not being so great as to be hazardous by making steering difficult, the normal crossfall should be 3% on paved roads and 4-6% on unpaved roads (TRL, 1993). A minimum cross fall of 2.5% is normally recommended in the form of either a straight camber extending from one edge to the other or as one sloped from the centre of the carriageway towards both edges. The primary aim of these cross falls is to adequately get rid of surface runoff from the highway pavement (MOW&H, 2005). viii) Side Slopes According to O’Flaherty (2002), soil mechanics analysis enables the accurate determination of maximum slopes at which embankments or cuts can safely stand. However, these maximum values are not always used, especially on low embankments not protected by safety fences. The slopes of embankments and cut sections depend upon the type of soil and the height of embankment or depth of cuttings. For reasons of economy, construction of steep side slopes on embankments and cuttings is encouraged Fore slopes steeper than 1:3 cannot be counted as part of the clear zone because they are too steep. Slopes that can be traversed safely by out-of-control vehicles need to be at least 1:4 or gentler. Slopes between 1:3 and 1:4 are marginal; The back slope design in cuts with a cut drain should be designed with a 0.5 m wide ditch bottom followed by a 1:4 back slope for half a metre and then a 1:2 slope for 2.0 m; this will help to redirect a run-off vehicle to the roadside area (MoWH&C, 2004). ix)

Vertical and Lateral clearance

Typical maximum truck heights are 4.2 meters and, to allow adequate vertical clearance and the transport of abnormal loads, a 5.0 meters vertical clearance should generally be ©Final Year Individual project, Upgrading Nsambya-Kirombe road to a bituminous paved surface. Kyambogo University, Kampala Uganda 2009/10

27

Kerbs

28

allowed for in the design.Lateral clearances between roadside objects and the edge of the shoulder should normally be 1.5 meters. This may be reduced to 1.0 m where the cost of providing the full 1.5 meters is high. Much smaller clearances will sometimes be necessary at specific locations such as on bridges, although a minimum of 1.0 meter will remain desirable. Minimum overall widths in such circumstances should be sufficient to allow the passage of traffic without an unacceptable reduction in speed, which will depend on the length of the reduced width section and levels of motorized and non-motorized traffic flow. Separate facilities should be provided for pedestrians where possible (TRL, 1993). viii) Roadway Markings Carriageway markings should be provided on all two-way paved roads. The edge of the carriageway should be delineated by continuous lines and may be supported by surfacing road studs or other features. The lines should be situated on the shoulder immediately adjacent to the running surface and should be at least 100mm in width. Centre line markings are also recommended on roads of at least 5 meters width designed for two lane operation in order that a driver may correctly locate his lateral position. These markings should be 100mm wide and normally be discontinuous. Except where overtaking is restricted and may be supported by the use of road studs. All markings should conform to international standards (TRL, 1993).


28

Pavement Design

2.4

Pavement Design

2.4.1

Introduction

29

A highway pavement is a structure whose primary aim is to support the traffic loads and transmit them to the basement soil after reducing the stresses to a level below the supporting capacity of the soil (Thagesen, 1996). a)

Types of pavements

Based upon the structural behaviour of the materials used in the construction, the pavements are generally classified into the following categories Flexible pavement and rigid pavement. i)

Flexible pavements

These are pavements which have very low flexural strength and are flexible in their structural behaviour under load (Singh, 2004).They maintain intimate contact with and distributes loads to the subgrade, they depend on aggregate interlock, particle friction, and cohesion for stability (Wright &paquatte, 1979).Since the author intends to design this type of pavement; the other will be left out. a)

Elements of flexible pavements

Most pavements consist of three superimposed layers each performing different primary functions (Thagesen, 1996). Figure 2.5 Pavement layers Wearing Course Base Course or Binder course

}

Surfacing

Road -base

sub-base

Subgrade

Source, TRL, 1993

i)

Surfacing

This is the uppermost layer of the pavement and will normally consist of a bituminous surface dressing or a layer of premixed bituminous material. Where premixed materials are laid in two layers, these are known as the wearing course and the base course (binder course) (TRL, 1993). The surfacing should be smooth and dust free, This


29

Road base

30

provides a riding surface for road users (Thagesen, 1996).it takes up wear and tear due to traffic, provides water tight surface against infiltration of surface water, provides hard surface that can withstand pressure exerted by tyres of vehicles (Singh, 2004).The author intends to recommend surfacing materials.

ii)

Road base

This is the main load-spreading layer of the Pavement. It will normally consist of crushed stone or gravel, or of gravely soils, decomposed rock, sands and sand-clays stabilized with cement, lime or bitumen (TRL, 1993). The functions of the base course are: •

Acts as a structural portion of the pavement and thus distribute load;

•

It prevents intrusion of the subgrade soils into the pavement (Kadiyali, 2000). The author will recommend road base materials for the road base.

iii)

Sub base

This is the secondary load-spreading layer underlying the road base. It will normally consist of a material of lower quality than that used in the road base such as unprocessed natural gravel, gravel-sand, or gravel-sand-clay. This layer also serves as a separating layer preventing contamination of the road base by the subgrade material and under wet conditions; it has an important role to play in protecting the subgrade from damage by construction traffic (TRL, 1993).The sub base is omitted when the subgrade is hard intact rock or if it is granular and has a CBR greater than 30% and without a high water table (TRL, 1993). Functions include minimizing damaging effect of frost action and facilitating drainage of free water that may get accumulated below the pavement. iv)

Capping layer

Where very weak soils are encountered, a capping layer is sometimes necessary. This may consist of better quality subgrade material imported from elsewhere or existing subgrade material improved by mechanical or chemical stabilization(TRL, 1993) .Unbound capping layers are normally made from gravely soils. A minimum CBR of 15% is recommended for material compacted to a specified density specifically 95% of the maximum dry density obtained with modified (heavy) compaction (Thagesen, 1996).


30

Subgrade.

vi)

31

Subgrade.

This is the upper layer of the natural soil which may be undisturbed local material or may be soil excavated elsewhere and placed as fill. In either case it is compacted during construction to give added strength (TRL, 1993) .Traffic load moving on the surface of the road is ultimately transferred to the subgrade through intermediate layers of sub base, base and wearing courses the pavement design assumes subgrade strength as the basis for designing the pavements, if the strength properties of the subgrade are inferior to the expected ones, it’s given suitable treatment to impart improvements in its performance (Singh, 2004). The author will carry out a subgrade assessment to determine its strength using UK DCP machine developed by TRL. b) Pavements design process There a different approaches to pavement design, some of which include, Analytic empirical method, terminal condition, AASTHO, mechanistic and CBR .The authors intends to use the CBR approach.

i)

Pavements design procedures

There are three main steps to be followed in designing a new road pavement these include; ii)

Traffic assessment

This involves estimating the amount of traffic and the cumulative number of equivalent standard axles that will use the road over the selected design life. Loads imposed by passenger cars don’t contribute significantly to the actual damage of the road pavements by traffic, therefore, for the purpose of pavement design, private cars are ignored and only the total number and axle loading of heavy vehicles; that will use the road during the design life are considered. In this context heavy vehicles are defined as those having an unladen weight of 300kg or more. In order to estimate the total of commercial vehicles that will traverse the pavement in the course of design life, its necessary to; the number of vehicles that that will use the road the first year the road is open, forecast annual growth rate of traffic And Select the design life (Thagesen, 1996). Manual classified counts will be carried out for this project and then project traffic using time analysis method. ©Final Year Individual project, Upgrading Nsambya-Kirombe road to a bituminous paved surface. Kyambogo University, Kampala Uganda 2009/10

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Subgrade assessment

32

The design life for this road shall be 15 years from a combination of a low reliability and high level of service. Table2.11: Pavement design life selection Design Data Reliability

Importance/Level of service Low

High

Low

10-15 years

15years

High

10-20 years

15-20 years

Source: Uganda Road Design Manual (2004)

iii)

Subgrade assessment

This is intended to determine the suitability of the subgrade soil over which the road is to be built. The strength of the subgrade is assessed in terms of California bearing ratio (CBR) and this is dependent on the type of soil, its density, and its moisture content (TRL, 1993).Overseas Road Note 31 deals more closely with the influence of water on the subgrade strength than other pavement methods. For estimation of the design moisture content, the subgrade moisture conditions under impermeable surfacing are classified into three categories. For designing the thickness of a road pavement, the strength of the subgrade should be taken as that of the soil at moisture content equal to the wettest moisture condition likely to occur in the subgrade after the road is opened to traffic. In the tropics, subgrade moisture conditions under the impermeable road pavements can be classified into three main categories: Category (1). Subgrade is where the water table is sufficiently close to the ground surface to control the subgrade moisture content. The type of subgrade soil governs the depth below the road surface at which a water table becomes the dominant influence on the subgrade moisture content. For example, in non-plastic soils the water table will dominate the subgrade moisture content when it rises to within 1 m of the road surface, in sandy clays (PI<20 per cent) .The water table will dominate when it rises to within 3m of the road surface, and in heavy clays (PI>40 percent) .The water table will dominate when it rises to within 7m of the road surface. In addition to areas where the water table is maintained by rainfall, this category includes coastal strips and flood plains where the water table is maintained by the sea, by a lake or by a river. Category (2). Subgrade with deep water tables and where rainfall is sufficient to produce significant changes in moisture conditions under the road. These conditions


32

Subgrade assessment

33

occur when rainfall exceeds evapotranspiration for at least two months of the year. The rainfall in such areas is usually greater than 250 mm per year and is often seasonal. Category (3). Sub grades in areas with no permanent water table near the ground surface and where the climate is dry throughout most of the year with an annual rainfall of 250 mm or less. Direct assessment of the likely strength or CBR of the subgrade soil is often difficult to make but its value can be inferred from an estimate of the density and equilibrium (or ultimate) moisture content of the subgrade together with knowledge of the relationship between strength, density and moisture content for the soil in question. This relationship must be determined in the Laboratory. The density of the subgrade soil can be controlled within limits by compaction at suitable moisture content at the time of construction. The moisture content of the subgrade soil is governed by the local climate and the depth of the water table below the road surface. In most circumstances, the first task is therefore to estimate the equilibrium moisture content as Outlined in below. Estimating the subgrade moisture content Category (1). The easiest method of estimating the design subgrade moisture content is to measure the moisture content in subgrade below existing pavements in similar situations at the time of the year when the water table is at its highest level. These pavements should be greater than 3m wide and more than two years old and samples should preferably be taken from under the carriageway about 0.5m from the edge. Allowance can be made for different soil types by virtue of the fact that the ratio of subgrade moisture content to plastic limit is the same for different subgrade soils when the water table and climatic conditions are similar. If there is no suitable road in the vicinity, the moisture content in the subgrade under an impermeable Pavement can be estimated from knowledge of the depth of the water table and the relationship between suction and moisture content for the subgrade soil The test apparatus required for determining this relationship is straightforward and the method is described in Appendix B. Category (2). When the water table is not near the ground Surface, the subgrade moisture condition under an impermeable pavement will depend on the balance between the water entering the subgrade through the shoulders and at the edges of the pavement during wet weather and the moisture leaving the ground by evapotranspiration during dry periods. Where the average annual rainfall is greater than 250mm a year, the ©Final Year Individual project, Upgrading Nsambya-Kirombe road to a bituminous paved surface. Kyambogo University, Kampala Uganda 2009/10

33

Material selection

34

moisture condition for design purposes can be taken as the optimum moisture content given by the British Standard (Light) Compaction Test, 2.5 kg rammer method. When deciding on the depth of the water table in Category (1) or Category (2) subgrade, the possibility of the existence of local perched water tables should be borne in mind and the effects of seasonal flooding (where this occurs) should not be overlooked. Category (3). In regions where the climate is dry throughout most of the year (annual rainfall 250 mm or less), the moisture content of the subgrade under an impermeable pavement will be low. For design purposes a value of 80 per cent of the Optimum moisture content obtained in the British Standard (Light) Compaction Test, 2.5 kg rammer method should be used. Compaction properties of the subgrade soil are determined by carrying out standard c)

Material selection

Selecting the most economical combination of pavement materials and layer thicknesses that will provide satisfactory service over the design life of the pavement (It is usually necessary to assume that an appropriate level of maintenance is also carried out (TRL, 1993). i)

Approach to design

There are various approaches of pavement design and they are classified into empirical and semi- empirical methods. An empirical method includes group index method, CBR method,. Semi- empirical method includes AASHTO method, tri-axial test, Notting ham method, California Resistance Value test, Macleod method, and Banister method. In Uganda, the AASHTO and CBR methods are most commonly applied. TRL 1993 provides a structure catalogue that can be utilized in determining the pavement thickness. ii)

Surface dressing

The design of surface dressing takes into account the type of existing road surface, traffic, the available chipping and climate (TRL, 1993). They can be applied as a single surface dressing or a double surface dressing. According to TRL, 1993, single surface dressing are suitable and adequate when applied to a bituminous layer. It’s quality must be very high in order for it to be satisfactory or non bituminous layer and their quality is enhanced if traffic is allowed to run on the first dressing for a period of 2-3 weeks. This allows the chipping of the first dressing to adopt a stable interlocking mosaic that provides a firm foundation for the second dressing. ©Final Year Individual project, Upgrading Nsambya-Kirombe road to a bituminous paved surface. Kyambogo University, Kampala Uganda 2009/10

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Material selection

35

Embedment of chippings under traffic depends upon the hardness of the layer to be sealed and the size of the chippings (TRL, 1993). Assessment of layer hardness can be based on descriptive definitions or measured using a simple penetration test probe. Details of surface category, penetration values and descriptive definitions are as shown below. The size of chippings chosen should suit the level of traffic and hardness of the underlying surface as shown in table •

Category of road surface hardness surface hardness

Road surface hardness is classified under the following Categories Table 2.12: surface category Surface Penetration at 0 Category 30 c(mm) Very hard

0-2

Hard

2-5

Normal

5-8

Soft

8-12

Very soft

>12

Definition Concrete or very lean bituminous structures with dry stony surfaces. There would be negligible penetration of chippings under the heaviest traffic. Likely to be an asphalt surfacing which has aged for several years and is showing somecracking. Chippings will penetrate only slightly under heavy traffic. Typically, an existing surface dressing which has aged but retains a dark and slightly bitumenrich appearance. Chippings will penetrate moderately under medium and heavy traffic. New asphalt surfacings or surface dressings which look bitumen-rich and have only slight surface texture. Surfaces into which chippings will penetrate considerably under medium and heavy traffic. Surfaces, usually a surface dressing which is very rich in binder and has virtually nosurface texture. Even large chippings will be submerged under heavy traffic.

Source, TRL, 1993

•

Traffic categories

The number of traffic is considered in terms of the number of commercial vehicles per day in the lane under consideration. The traffic categories are defined in table below. It should be noted that, this differs from the traffic class used in the selection of the pavement structure Table 2.13: Traffic categories Approximate Nunber of Vehicles Category with unladen weights greater than 1.5tonnes(per day) 1

over 2002

2

1000-2002

3

200-1000

4

40-200

5

Less than 20

Source: TRL (1993)

iii)

Chippings

The nominal size of chippings is chosen to suit the level of traffic and hardness of the underlying surfaces shown in table. In selecting the nominal size of chippings from ©Final Year Individual project, Upgrading Nsambya-Kirombe road to a bituminous paved surface. Kyambogo University, Kampala Uganda 2009/10

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Binder

36

double surface dressing, the size of chipping of the first layer should be selected on the basis of the hardness of the existing surface and the traffic category as indicated in table (TRL, 1993). Table 2.14: Nominal size of chippings Surface Category

Traffic ctegory

Very hard Hard

1 10 14

2 10 14

3 6 10

4 6 6

5 6 6

Normal

20

14

14

10

6

Soft

*

20

14

14

10

Source: TRL, 1993

The nominal size of chipping selected for the second layer should be about half the nominal size of the first layer to promote good interlock between the layers. The least dimension of at least 200 chippings should be measured and the average Least Dimension (ALD) determined. This is then used in the figure (see appendix) together with the line labelled AB and the approximate rate of chippings read from the upper scale (TRL, 1993). iv) Binder The rate of application of binder is determined using appropriate factor from table 2.4 below for each of the four sets of conditions listed. The four factors are then added together to give the total weighting factor. The Least Dimension of the chippings and the total weighting factor obtained from the condition constants are then used to obtain the rate of application to binder (TRL, 1993,). Table 2.15: Condition for determining the rate of application of the binder Traffic Vehicle/day Constant Type of Chipping Constant +3 Very light 0-50 Round/dusty +2 light 50-250 +1 Cubical 0 Medium

250-500

0

Flaky

-2

Medium -Heavy

500-1500

-1

Precoated

-2

Heavy

1500-3000

-3

3000+

-5

Very Heavy Existing Surface

ClimateCondition

Untreated/Primed road base

+6

Wet and cold

+2

Very lean bituminous

+4

Tropical(Wet and hot)

+1

Lean bituminous

0

Temperate

0

Average bituminous

-1

Semi arid(Dry and hot)

-1

Very rich bituminous

-3

Arid(Very dry and very hot)

-2

Source: TRL, 1993


36

Unbound pavement materials

37

The ESA of design traffic volume is computed basing on the AASHTO method in TRL and shown in. Only commercial and heavy goods vehicles with axle weights greater than,1,500kg are considered. The pavement thickness is determined from the structure catalogue using the traffic class together with the CBR value of the sub grade (sub grade strength). Where the CBR of sub grade exceeds 30%, then there is no need for the sub -base layer. Thickness of surfacing of a pavement largely depends on the traffic anticipated to use that pavement. The loads imposed by private cares with un–laden weight less than 1500kg and motorcycles do not contribute significantly to the structural design cars caused to road pavements traffic. Therefore for the purpose of structural design cars and motorcycles can be ignored and only a total number and axle loading of commercial vehicles that will use the road during it’s design life need to be considered. Commercial vehicles can be defined as goods or public service vehicles that have un-laden weight of 1500kg or more. However during traffic census a count of all types of vehicles is carried out and these counts are expressed in design value called passenger car unit (P.C.U) this data is used in high way planning and hence the design of road pavements, control measures, cost benefit analysis, accidents etc. Estimating the number of vehicles Traffic census is normally carried out mainly:To know the number of commercial vehicles that will use the road when it is first opened to traffic. To forecast the annual growth of traffic The most probable information of the initial traffic flow can be obtained from the results of the traffic counts taken along the existing road. This gives the number of vehicles that flow on the road per day and hence average daily traffic (A.D.T). d) Unbound pavement materials Selection of unbound materials for use as road base, sub base, capping and selected sub grade layer normally depends on the properties of unbound materials (TRL1993).


37

Natural Occurring granular materials (Road Base)

38

The main categories with a brief summary of their characteristics are shown in table Table 2.16: Properties of unbound materials Code Description GBI.A Fresh, crushed rocks

Crushed rocks, gravel or boulders GB2.A Dry- bound macadam GBI.B

Summary of Specification Dense graded, un- weathered crushed stones, .Non -plastic parent fines Dense grading, P1<6 . Soil or parent P1<6 Aggregate properties as for GBI.B,P1<6 Aggregate properties as for GBI .B P1<6 Dense grading , P1<6, CBR after soaking >80

GB2.B Water- bound macadam GB3 Natural coarsely granular materials including processed and modified gravels GS Natural gravel CBR after soaking >80 GC Gravel or gravel -soil Dense graded, CBR after soaking >15

Source: TRL, 1993

These specifications are sometimes modified according to site conditions, materials type and principal use. GB= Granular road base, GS= Granular sub –base, GC= granular capping layer i.


According to (TRL, 1993), a wide range of materials including Lateritic, calcareous and quartzite gravels, river gravels and transported gravel, or granular materials resulting from the weathering of rock can be used successfully as road bases. Table 2.26 below contain three recommended particle size distribution for materials corresponding to maximum nominal sizes of 37.5mm, 20mm, and 10mm. Recommended particle size distribution for mechanically stable natural gravels and weathered rocks for the use as road bases (GB3) Table 2.17: grading

BS Test Sieve

50 37.5 20 10 5 2.36 0.425 0.075

Percentage by mass of total aggregates passing Test Sieve Nominal Maximum Particle Size 37.5mm 20mm 10mm 100 80-100 100 0 60-80 80-100 100 45-65 55-80 80-100 30-50 40-60 50-70 20-40 30-50 35-50 10-15 12-27 12-30 5-15 5-15 5-15


38


ii)

39

Sub–Base materials (GS)

The selection of sub-base materials depends on the design function of the layer and the anticipated moisture regime both in service and at construction. Since sub- bases act as a working platform for the construction of the upper pavement layers and as a separating layer between sub grade and road base (TRL, 1993) a minimum CBR of 30% is required at the highest anticipated moisture content when compacted to the specified field density, usually a minimum of 95% of MDD. To achieve the required bearing capacity, and for uniform support to be provided to the upper pavement, limits on soil plasticity and particle size distribution may be required. Materials that meet the recommendations of table 2.18and 2.19 below will usually be found to have adequate bearing capacity. Table 2.18: Recommended plasticity characteristics for granular sub base (GS)., Climate Liguid Limit Plasticity Index Linear Shrinkage <6 <3 Moist tropical and wet tropical<35 Seasonally wet tropical <45 <12 <6 Arid and semi- arid <55 <20 <10 Source, TRL, 1993

Table 2.19: Typical particle size distribution for sub base (GS) which will meet strength requirements BS sieve size (mm) 50 37.5 20 5 1.18 0.3 0.75

Percentage by mass of Total aggregate passing test sieve 100 80-100 60-100 30-100 17-75 9-50 5-25

The following criteria are used in evaluating a sub base as a separating or filter layer. The ratio D15/D18 (coarse layer / fine layer) <5 Where; D15 = Sieve size through which 15% by weight of the materials passes D85=Sieve sizes through which 85% passes The ratio D50/D50 (coarse layer / fine layer) <25 For a filter to possess the required drainage characteristics, a further requirement is,The ratio D15/ D15 (coarse layer) (fine layer) should lie between 5 and 40.


39

Aggregates

40

These criteria may be applied to the materials at both the road base/ sub base and the sub base – base-grade interface (TRL, 1993) iii)

Aggregates

For road construction, aggregates play a role in bearing the main stresses occurring in the road pavement as a result of application of static , traffic or dynamic loads, the necessity

of the

geological production and testing of aggregate properties and

characteristics must be carefully assessed if the aggregates are to meet the required purpose. Aggregates are obtained from natural rocks that occur as rock outcrops, gravel or sand. The physical properties governing the suitability of aggregates for use differs not only widely in each group but also often show considerable variation in samples taken at different times from the same parent . Aggregate properties and their significance •

Road aggregates should be strong enough to withstand stresses caused by traffic loads

•

Offers resistance to abrasive action of traffic, normally in the wearing coarse

•

They take up subjected wheel impact loading

•

Aggregates should be capable of standing test of time by resisting weathering agent’s e.g. Rain during the design life of the road.

•

Cubical–angular aggregates are normally preferred because of their high affinity for bitumen and water.

Some of the tests carried on aggregates include the Following a)

Flakiness index (FI) test

Flakiness index is an empirical factor expressing the total material passing through the slots of the thickness gauge as the percentage of the mass of the sample taken for testing. The test is not applicable to aggregate sizes less than 6.3mm. Aggregates are classified as flaky when they have a thickness of less than 60% of their mean sieve size. This is a test carried out to determine the shape and angularity of the aggregate particles, in order to analyze its suitability for use as a stone base or a surfacing material or bituminous base course. The test is carried out as per BS812: section 105.1:1989 Its one of the tests used in the classification of stones and aggregates. In pavement design there are specific requirements regarding the flakiness index of materials. For


40

Aggregate least dimension (ALD)

41

base course and wearing course aggregates, the presence of flaky particles are considered undesirable as they may cause inherent weakness with a possibility of breaking down under traffic loading. The lower the flakiness index, the more cubicles the chippings are and this guarantee a better particle interlock and a stable mosaic. When the material is used as stone base or a surfacing material, the end result is a stable and strong pavement structure. The specifications for the different area of use are; •

For stone base 30% maximum.

•

For surface dressing and thin premix surface a maximum of 30%

•

For bituminous macadam base course a maximum of 35%.

b)

Aggregate least dimension (ALD)

This is the minimum dimension of the aggregate required for surface dressing, determined from the results of; Flakiness index and the average value of the sieve size through which 50% of the aggregate sample pass, when the two values are plotted on a monogram TRL (1993). The maximum aggregate size required for surface dressing is a function of the road surface hardness and the traffic category. The next lower size required is the Average Least Dimension TRL (1993). The Average Least Dimension (ALD) should not be less than half the maximum sieve size, derived from the traffic category and the road surface hardness i.e. 20/14, 14/10, and 10/6. c)

Aggregate crushing value (ACV) test

This test is carried out to examine the crushing strength of the aggregates to be used in road base or surfacing. The crushing strength is reported in terms of “Aggregate Crushing Value or ACV”. The test is carried out as per BS 812:Part110:1990. A load of up to 400KN is gradually applied on the test sample of aggregates passing 14mm sieve and retained on 10mm sieve placed in a cylinder. The test result gives an indication of the strength characteristics of the aggregate in resisting crushing due to compressive force of the rollers and wheel loads during the design life of the road pavement. Pavement failure can result from crushing of the aggregates. The higher the ACV percentage the more susceptible are the aggregates to crushing and the lower the ACV percentage the better is the aggregate resistance to ©Final Year Individual project, Upgrading Nsambya-Kirombe road to a bituminous paved surface. Kyambogo University, Kampala Uganda 2009/10

41

Aggregate impact value (AIV) test

42

crushing and thus better performance during wheel loading. The strength is categorized as;

Exceptionally strong for ACV < 10% Very weak for ACV > 35 % An aggregate with a maximum ACV 30% is recommended for use on road base and surfacing (Kadiyali. 2006). d)

Aggregate impact value (AIV) test

This is the test designed to evaluate the resistances of an aggregate to sudden impact. The measure of this resistance is reported quantitatively in terms of “Aggregate Impact Value or AIV”. The test is carried out as per BS 812:Part112: 1990. An aggregate sample passing a BS 14mm sieve and retained on 10mm sieve is placed in layers in a test cylinder to full capacity, each layer receiving 25 blows from a tamping rod, and then subjected to an impact from a free falling harmer. The weight of the crushed sample passing through BS 2.36mm sieve is expressed as a percentage of the total mass of the sample as a measure of the “Aggregate Impact Value”. The test gives an indication of the relative resistance of the aggregate to sudden shock or impact loading during compaction and also due to wheel loading on a road pavement. If the AIV is too high, it means that the aggregate is susceptible to crushing during the design life of the pavement and this significantly affects the durability of the road. Depending on pavement layer on which the aggregate will be used, there is a maximum value of AIV above which a particular aggregate is regarded as unsuitable. The following are recommended. •

For surfacing course a maximum AIV of 30%

•

For a base course a maximum AIV of 40%

•

For a sub base a maximum AIV of 50% Kadiyali(2006).

e)

Ten percent fines value (TFV) test

This test is carried out to determine the force required to crush an aggregate sample passing BS 14mm sieve and retained on 10mm sieve so that 10% of the crushed material passes through the BS 2.36mm sieve after crushing. The test gives a relative resistance of the aggregate to crushing due to a gradually applied load that will cause a ©Final Year Individual project, Upgrading Nsambya-Kirombe road to a bituminous paved surface. Kyambogo University, Kampala Uganda 2009/10

42

Los Angeles Abrasion Value Test. (LAAV)

43

penetration of 20mm in ten (10) minutes. The test is carried out as per BS 812: Part 111:1990 The test gives an indication of the strength of the aggregates that is reported quantitatively as a force. The higher the force, the stronger is the aggregate and the lower the force, the weaker is the aggregate. Weaker aggregate are undesirable in pavement construction or design. Stronger aggregates have better performance in resisting the traffic loading. For an aggregate to be guaranteed that it will not crush under traffic loading, it must have a minimum Ten Percent Fines (TPF) value of 110KN. The aggregate meeting this criterion qualifies to be used in surfacing and road base. f)

Los Angeles Abrasion Value Test. (LAAV)

The test is designed to evaluate the resistance of the mineral aggregate of standard grading to degradation resulting from abrasion, impact and grinding. The test is carried out as per ASTM 539-89.The measure of this resistance is reported quantitatively in terms of “Los Angeles Abrasion Value (LAAV). For coarse aggregates used in pavement construction, or surfacing course, the aggregates are subjected to constant wearing at the top and may get abraded due to the movement of traffic. High abrasive value is an indication of very weak aggregates, which leads to very low durability, whereas aggregate with low abrasion value will lead to construction of a more durable road. This is based on a standard maximum value of the abrasion test result that will lead to better performance, offering a high durability during service. This value is usually set at a maximum of 30% percent for road base and 25% for the surfacing course. iv)

Bitumen

Bitumen is a dark bituminous product which is a conglomeration of compels hydrocarbons. The process of atmospheric distillation produces most bitumen. There are two main properties used as basis for the grading of bitumen: • Viscosity (mostly used in U.S.A, European countries) .This refers to resistance to flow within or without fluids; •

Penetration (mostly used in Uganda.

Grading based on viscosity


43

Bitumen

44

The standard bitumen grade is ASTMD 3381. There are various grades: AC-5, AC-10 AC-30, and C-40. Where AC refers to asphalt cement. The numbers, 5, 10, 30 and 40 designates the viscosity of the bitumen at standard temperature of 60oC.

a)

Types of tar products

i)

Coating tars. These are graded with a C. There are a number of grades namely

C-30, C-34, C-24, C-50, C-54 and C-58.The following tests are carried out on bitumen The Penetration Test, The Viscosity Test, The Softening Point Test The Flash Point Test, The Fire Point Test, The Marshall Test. Penetration of a bituminous material is the distance in tenths of a mm, that a standard needle weighing 100g would penetrate vertically into a sample of the material under standard conditions of temperature, and time. The needle is allowed to penetrate into the sample for five (5) seconds at a temperature of 25 0C.The penetration test is in no way indicative of the quality of the bitumen but does allow the material to be classified. The softening point is the temperature at which all refinery bitumen have the same viscosity (about 1200 Pa.s).This test is also referred to as the Ring and Ball Test. The softening point of bitumen or tar is the temperature at which the substance attains a particular degree of softening. It is the temperature at which a standard ball passes through a sample of bitumen in a mould and falls through a height of 2.5 cm, when heated under water or glycerine at specified conditions of the test. The binder should have sufficient fluidity before its application in roads uses. The determination of the softening point helps to know the temperature up to which a bituminous binder should be heated for various road use applications. This test is done to determine the flash point and the fire point of asphaltic bitumen and fluxed native asphalt, cutback bitumen and blown type bitumen as per IS: 1209 – 1978. The principle behind this test is given below: Flash Point – The flash point of a material is the lowest temperature at which the application of test flame causes the vapors from the material to momentarily catch fire in the form of a flash under specified conditions of the test.


44

Bitumen

45

Fire Point – The fire point is the lowest temperature at which the application of a test flame causes the material to ignite and burn at least for 5 seconds under specified conditions of the test. At high temperature, bituminous materials emit hydrocarbon vapors which are susceptible to catch fire. Therefore the heating temperature of bituminous material should be restricted to avoid hazardous conditions. The flash point is one measure of the tendency of the test specimen to form a flammable mixture with air under controlled laboratory conditions. It is only one of a number of properties that should be considered in assessing the overall flammability hazard of a material. Flash point is used in shipping and safety regulations to define flammable and combustible materials. Flash point can indicate the possible presence of highly volatile and flammable materials in a relatively nonvolatile or nonflammable material. For example, an abnormally low flash point on a test specimen of engine oil can indicate gasoline contamination. This test method shall be used to measure and describe the properties of materials, products, or assemblies in response to heat and a test flame under controlled laboratory conditions and shall not be used to describe or appraise the fire hazard or fire risk of materials, products, or assemblies under actual fire conditions. Flash point and fire point tests are used to determine the temperature to which bituminous material can safely be heated i.e. the safety of the working group on site and care is necessary when handling with medium and rapid curing cutback bitumen whose flash and fire points are low. The fire point is one measure of the tendency of the test specimen to support combustion b) The Marshall Method Asphalt concrete and sand asphalt is usually designed using the Marshall method by choosing the optimum binder content for a particular mix. While rolled asphalt and asphalt macadam are often made to recipe specification. The test procedure is used in designing and evaluating bituminous paving mixes and is widely applied in routine test programs for the paving roads. The major features of the test are to determine the two important properties of strength and flexibility. ©Final Year Individual project, Upgrading Nsambya-Kirombe road to a bituminous paved surface. Kyambogo University, Kampala Uganda 2009/10

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Bitumen

46

Strength is measured in terms of the marshal stability of the mix defined as the maximum load carried by a compacted specimen at a standard test temperature of 60 oc.this temperature represents the weakest condition for a bituminous pavement in use. The flexibility is measured in terms of the flow value which is measured by change in diameter of the sample in the direction of load application between the start of the loading and the time of maximum load. In this test an attempt is made to obtain optimum binder content for the aggregate mix type and traffic intensity. i)

Viscosity

Is a property of a fluid that retards its flow .The viscosity of a fluid slows down its ability to flow and is of particularly significance at high temperatures when the ability of the bitumen to be sprayed on to or mixed with aggregate material is of great significance .The main objective of carrying out this test is to determine the viscosity of bituminous binder. Viscosity of a fluid is the property by virtue of which it offers resistance to flow. The higher the viscosity, the slower will be the movement of the liquid. The viscosity affects the ability of the binder to spread, move into full up the voids between aggregates. It also plays an important role in coating of aggregates. Highly viscous binder may not fill up the voids completely thereby resulting in poor density of the mix. At lower viscosity, the binder does not hold the aggregates together but just acts as a lubricant. Viscosity is also important in determining the workability of the mix. The viscosity of bituminous binders falls rapidly as the temperatures rise. Since binder’s exhibit viscosity over a wider range, it is necessary to use different methods for the determination of viscosity.


46

Drainage design

2.5

Drainage design

2.5.1

Introduction

47

Highway drainage may be defined as the process of interception and removal of water from over, under, and the vicinity of the road surface (Singh, 2004).One of the most important aspects of road design is the provision made for protecting the road from surface and ground water on the pavement as it slows traffic and contributes to accidents from hydroplaning and loss of visibility from splash and spray. If water is allowed to enter the structure of the road, the pavement and the subgrade will be weakened and it will be more susceptible to damage by traffic when roads fail it’s usually due to inadequate drainage. The drainage system has four main functions: •

To convey storm water from the surface of the carriageway to outfalls;

•

To control the level of water table in the sub grade beneath the carriageway;

•

To intercept ground water and surface water flowing towards the road;

•

To convey water across the alignment of the road in a controlled fashion.

The first three functions are performed by longitudinal drainage components, in particular side drains, while the fourth function requires cross-drainage structures such as culverts, fords, drifts and bridges (Thagesen, 1996). 2.5.2

Types of drainage

There are basically three types of drainage systems, these include; Surface drainage, Subsurface and cross drainage. a)

Longitudinal drainage

The road surface must be constructed with sufficient camber or cross– fall to shed rain water quickly ; and the formation of the road must be raised above the level of the local ground water table. It is important to maintain a minimum longitudinal gradient on curbed pavements than on uncurbed pavements in order to avoid undue spread of storm water on the pavement. Vegetation along the pavement edge may impede the runoff of water from uncurbed pavements if the gradient is flat. Where the longitudinal gradient of the roadway has to be near zero, the depth of side drains may have to be varied to obtain sufficient gradient of the ditch. The longitudinal gradient should therefore preferably not be less than 0.3% for curbed pavements and not less than 0.2% in very flat terrain. (Thagesen, 1996) ©Final Year Individual project, Upgrading Nsambya-Kirombe road to a bituminous paved surface. Kyambogo University, Kampala Uganda 2009/10

47

Types of drainage

48

According to Thagesen, Longitudinal drainage can be classified into various forms of open roadside drainage channels basing on the various functions they perform. i)

Ditches: These are channels provided to remove the runoff from the road

pavement, shoulders and cut and fill slopes. Its depth should be sufficient to remove the water without risk of saturating the pavement sub grade. It may be lined to control erosion.

Unlined ditches should preferably have side slopes not steeper than 4

horizontal to 1 vertical). ii)

Gutters: They are the channels at the edges of the pavement or the shoulder

formed by a curb or by a shallow depression. They can paved with concrete, bricks stone blocks or other structural materials. iii)

Turnouts; or “Mitre drains”. They are short, open, and skew ditches used to

remove water from the roadside ditches or gutters. They are used to reduce the sizes of the side ditches and minimize the velocity of water and thereby the risk of erosion. These must be provided at intervals depending on the runoff, permissible velocity of the water and slope of the terrain. iv)

Chutes: they are also open, lined channels or closed pipes used to convey water

from gutters and side ditches down fill slopes and from intercepting ditches down cut slopes. Their interval of placing depends on the capacity of gutter or ditches. Intercepting ditches; they are sometimes referred to as “Cut-off” ditches. They are located on the natural ground near the top edge of a cut slope or along the edge of the right-of–way. They serve to intercept the run-off from hillside before it reaches the road. Intercepting the surface flow reduces erosion of cut slopes and roadside ditches, lessens silt deposition and infiltration in the roadbed, area and decreases the likelihood of flooding the road in service storms. ii)

Design of Longitudinal drainage

The hydraulic capacity of drainage channels is often designed to contain a 5-or 10-year frequency storm runoff. The estimated runoff for the two–year storm can be used for determining the needs, type and dimensions of special channels lining for erosion control. The design discharge ( Q ) is calculated according to the rational formula: Q=

C×I× A 3.6

..2.20


48

Types of drainage

49

Where: Q =Flood peak at catchment’s exit in m3/sec

C = Rational runoff coefficient (see below) I = Average corresponding to the time of concentration (see below) A = Catchment’s area in Km2 Note: The time of concentration is defined as the time required for the surface runoff from the remotest part of the drainage basin to reach the point considered. It can be calculated by the Kirpichs’ formula: Time of Concentration This is a function of the length of water course and height difference from the source to outflow. It’s given by the formula below;  0.87 L3  Tc =    H 

0.385

In hrs

…2.21

Where; Tc

=

Time of concentration;

L

=

Length (in km) of the longest water course from exit;

H

=

Height difference (in m) from source to exit;

When Tc is determined, the corresponding rainfall intensity can then be obtained from the Intensity-Duration-Frequency curve Tc= Time of concentration in hours L= Distance from the remotest part to the point of interest in Km S =fall (average slope) in level from the remotest part to point of interest in mm-1 After determining the design discharge (Q), then the capacity of an open channel is calculated according to the manning equation, which gives a reliable estimate of uniform flow conditions (Thagesen, 1996)as shown below. 1 Q = A × v = A × ×R 2/3 × l1/2 Where: n


49

Types of drainage

50

Q = Capacity in m3/sec

A = Channel crosssectional area in m2 v = Mean velocity in m/sec

n = Manning roughness coefficient l =slope in mm-1 R =hydraulic radius A/P in m P= wetted perimeter in m. The maximum velocity (V) can be chosen from table depending on the nature of bed surface . b)

Cross drainage

Cross- drainage structures can be very costly and it is therefore important to analyse all major cross- drainage along alignment before final selection of a new road alignment. Where there is a choice in the selection of the position of a stream crossing, it is desirable that, as far as possible, the stream is located on a straight reach of the stream, away from bends •

As far as possible from the influence of large tributaries;

•

On reach with well defined banks;

•

At a site which makes a right angle approach road possible;

•

At a site which makes a right angle crossing possible.

To determine the type of cross- drainage, relevant information on hydrology must be collected, and predictions about the level of traffic should be made. The following type of structures may be considered:-Fords, Drifts, Culverts, Bridges (Thagesen, 1996). However, for this project purpose, culverts where considered as the cross drainage structures. They are used to convey water from streams below the road and to carry water from the one side ditch to the other. Culverts can be made of concrete or steel pipes. The common forms of concrete culverts used in Uganda are the PCC with sizes ranging from 450mm-to- 1200mm and reinforced concrete box (box culverts). Common steel pipes include among others; corrugated galvanized steel pipe (often known by the trade name”

Armco” with sizes ranging from 450mm- 1500mm

(Thagesen, 1996).


50

Culvert structure

i.

51

Culvert structure

Most culverts begin up stream with the inlet structure and terminate down stream with the outlet structure. Headwalls direct the flow into the culvert, while end walls provide a transition from the culvert to the outlet channel both protect the embankment from erosion by flood waters. The whole system is termed as culvert structure which comprises of:Inlet structure: allows in the storm water through the culvert. It may be constructed as a single unit called headwall or as a combination of various units such as wing walls, or drop-in chambers.

A combination of materials can be used to construct an inlet

structure, which includes plain concrete, reinforced concrete masonry walls in brick, blocks or stone blocks. Barrel: This is the entire arrangement of culverts to a certain gradient to form a tunnel- like structure for storm water passage. It joins both the inlet and outlet structures together. Outlet structure; It serves the purpose of discharging the storm water from the culvert to the outlet channel. Its construction is similar to that of inlet structure. Apron: a concrete slab constructed at both the inlet and outlet structures. It provides a transition from channel to culvert (inlet) and from culvert to channel (Outlet). Sometimes, it is constructed with or without cut-off wall (toe wall). Culvert bed. This is a layer upon which the culvert units are laid to gradient placed properly over the sub grade (Thagesen, 1996).

ii)

Culvert Design

Culvert is designed to operate in a manner that is within acceptable limits of risk at that flow rate. It is necessary to determination of culvert sizes (Thagesen, 1996). Location of the culverts should be selected carefully. The alignment of the culvert should conform to the alignment of the natural stream. The culvert should if possible cross at right angles to the roadway for economy-` however skew culverts located at an angle to the centreline of the road are needed in many instances. The slope of the culvert should generally conform to the existing slope of the stream. to avoid silting, the slope of the culvert should not be less than 1% Before explaining the procedure for the determination of culvert sizes its necessary to define the following concepts. ©Final Year Individual project, Upgrading Nsambya-Kirombe road to a bituminous paved surface. Kyambogo University, Kampala Uganda 2009/10

51

Headwater depth •

52

Head water depth: The total flow depth in the stream measured from culvert inlet

invert • Tail water depth the flow depth in the down stream channel measured from the invert at the culvert outlet • Outlet velocity Is the velocity measured at the down stream end of the culvert, and it is usually higher than the maximum natural stream velocity There are two major types of culvert flows; Flow with inlet control and Flow with outlet control. For each type of control, a different combination of factors is controlling the hydraulic capacity of a culvert. The determination of actual flow conditions can be difficult. Therefore, the designer should check for both types of flow and design for the most adverse condition. A Culvert operates with inlet control when the flow capacity is controlled at the entrance by the following factors; Culvert type (shape of barrel), Type of culvert inlet, Culvert crosssectional area. Headwater depth When a given culvert operates under inlet control the headwater depth determines the culvert capacity with the barrel usually flowing only partially full. Culvert flow with outlet control: here the flow capacity is determined by the same factors as under inlet control, but in addition to that , the performance depends on:-Roughness of the inner surface of the culvert (barrel roughness), longitudinal slope of the culvert (barrel slope), Design procedure In order to find the size of the culvert and the velocity at the outlet under a given set of conditions, it is first necessary to determine the probable type of flow under which the culvert operates. There are basically six steps in designing a culvert • List the design data such as • Design discharge in m3/ sec • Approximate length of culvert in m. • Slope of culvert in m m-1 • Allowable water headwater depth in m • Slope of culvert in mm-1 • Mean and maximum flood velocity in natural stream in m/sec • Type of culvert for the 1 st trail; including barrel materials, barrel cross-sectional shape and inlet type. ©Final Year Individual project, Upgrading Nsambya-Kirombe road to a bituminous paved surface. Kyambogo University, Kampala Uganda 2009/10

52

Headwater depth •

Select the 1st trail size of culvert

•

Find the headwater depth for the trail– size culvert

•

Try a culvert of another type or shape and determine the size and HW by the above

53

procedure •

Compute the outlet velocity for the size and types of culvert

•

Record final selection of culvert with type, size required headwater, outlet velocity and economic justification. (Thagesen, 1996).

However, there are other approaches, which simplify the design. It considers the maximum discharge (Q max) and the maximum flow velocity (Vmax) so as to estimate the minim culvert size in meters.

This later approach was adopted for academic

purpose. c)

Sub surface Drainage

Stability and strength of the road surface depends upon the strength of the subgrade. Subgrade is the foundation layer of the road whose strength largely depends upon its moisture content. Variations in moisture content of subgrade are caused by •

Seepage of water from higher adjoining land

•

Penetration of moisture through the pavement.

•

Percolation of water from shoulders, pavement edges, and soil formation slopes.

•

Rise and fall of underground water table

•

Capillary rise of moisture in case of retentive type of soils and transfer of moisture vapour through soil. This project did not take into account subsurface drainage, because of time limitations.


53

Chapter Summary

54

Chapter Summary The literature review’s main objective was to build up a theoretical understanding of the subject prior to undertaking the project so as to form a foundation for the methodology, design conclusions and recommendations to be used later in the report. Different text books where consulted pertaining flexible pavement designs, flexible pavement design was chosen since it’s economical and can serve the purpose. The present state of the road will be reviewed, surveying using a total station will be carried out,subgrade shall be tested using a dynamic cone penetrometor, rainfall data from the metrological department shall be obtained so as to analyse the hydrology of the area and. The project road is a class C gravel road, having a rolling terrain, maximum grades shall be limited to 9%, minimum radius of the curves will be 100m, and minimum CBR of the subgrade according to TRL is supposed to be 15% .Borrow material will be test to ascertain its sustainability and Surface dressing will be used for economic purposes.


54

55

3.0

Methodology

3.1

General

Having reviewed the necessary literature, data was then collected from various authorities such as the Metrological department under the Ministry of Water, Lands and Environment, Methodology is divided into four main headings of Data Collection and classification, modeling and analysis, design and simulation, publication and dissemination. 3.1.1 Data collection and classification i)

Surveying

A detailed topographical survey was carried out using a total station to enable preparation of detailed geometric alignment designs and determination of construction quantities.

Sections of road centreline, shoulders, existing sidedrains, any other

significant features such as houses and any significant changes in the terrain were captured. These were taken at intervals of 25 metres. See appendix C for survey data. Two Survey control points were established at intervals of 700m as recommended by the Uganda geometric design manual 2005.these were BM1 (1109.731, 841.209) at 1193.436m and BM2 (1017.455, 423.384) at 1201.053m.see appendix I-1 for the bench marks. Coordinates were then entered into an excel sheet in the form PENZD (Point, Easting, Northing, Elevation and Description) and then converted to comma separated values and imported into AutoCAD Land development to generate a digital terrain model. ii)

Traffic

Traffic assessment was done according to the recommendations of TRL, ORN 31, as follows; the counts were carried out for seven consecutive days. The counts on Friday and Saturday were for a full 24 hours, with Friday as a representative week day and Saturday as a representative weekend. On the other days, they were 16-hour counts. The following steps were generally taken when carrying out a traffic survey; Traffic count data sheets were processed indicating the classification of vehicles, i.e. cars, Pick-ups, minibuses, buses, trucks and trailers. A traffic count station along the road was then


55

Data collection and classification

56

identified; Enumerators were then trained to carry out the traffic survey and positioned in the identified station. data collected was then analysed. Time series analysis was then used to obtain growth rates for different vehicles based on the data obtained from URA. This statistical approach was based on the straight line equation. Yt = a + bx

…3.1

Yt =trend value for a given time period a =value of Yt when x is at the origin b =slope of the line, or the increase or decrease in Yt for each change of one unit time x =any time period selected Since the years 2000/1 to 2007/08 are even, time(x) was coded -1,-3,-5 and -7 for the years 2000/1,2001/02,2002/03,2004/05 and 1,3,5 and 7 for the years 2004/05,2005/06,2006/07 and 2007/08. A scatter diagram was then plotted in excel to obtain a line of best fit for each vehicle classification over the 8 years. Constants a and b were obtained as follows: a=

b=

•Y n

… 3.2

•(xY) •(x2 )

…3.3

Growth rates were then obtained from the relationship: b r(%) = ×100 a

…3.4

Traffic projection was then carried out using the formula: Pn = Po (1+ r)n

…3.5

Where: Pn and Po are design and base year flows respectively r is the vehicle growth rate (%) n is the design life ii)

Subgrade assessment

In order to determine the subgrade strength, a dynamic cone penetromer (DCP) was used.DCP test was carried out in accordance with TRL Recommendations. The readings were taken be taken at increments according to the strength of the layer being penetrated. DCP results were then fed into the UK-DCP software a computer


56

Modeling and analysis

57

programme developed by TRL which interpreted and presented of DCP data. The CBR at a depth of 475mm was obtained. See Appendix D

Other tests on the subgrade were also carried out to determine the suitability of the subgrade.these include the following •

The British Standard Heavy compaction test in accordance with BS 1377 Part 4 1990. This test produces a density value which represents a reasonable achievable density which will give a well compacted soil and a moisture content value which represents the best moisture content the soil should have in order to obtain the maximum benefit from the comp active effort used.

•

Particle size distribution in accordance to 1377 part 2 1990 to classify the soil

•

Atterberg limit tests in accordance with BS Part 2 1990 to determine the plasticity of the subgrade soil

• a)

Moisture content in accordance to BS 1377 Part 2 1990 Material selection

Borrow pits were surveyed and suitability of the borrow material ascertained Borrow pits surveyed include; kangulumira quarry in Mukono. Rainfall data from the metrological department was obtained to enable hydrological analysis; a topographical map of the project area was also obtained to determine the catchment area. 3.1.2 Modeling and analysis This involved the preparation of detailed engineering design drawings including plan and profile drawings, typical cross-sections using AutoCAD land development 2007 version. A digital terrain model was generated using land development 2007 version for design, Horizontal alignment was generated by fitting tangents to curves, centreline was defined, and offsets were created. For designing drainage, topographical maps were obtained from the metrological department of Entebbe to enable hydrological analysis. 3.1.3 Simulation and design Designing was done using the following standards, Transport Research Laboratory, (TRL), Association of American State Highway and Transportation Officials (AASHTO), South African.National.Roads.Agency, (SANRA) South. African and ©Final Year Individual project, Upgrading Nsambya-Kirombe road to a bituminous paved surface. Kyambogo University, Kampala Uganda 2009/10

57

Publication and dissemination

58

Communications Commission (SATCC) and the Uganda Design Manual. Mainly the Uganda road design manual was employed; others were used for comparison purposes. While Simulation was intended to be done by Civil Simulate, but due to the scarcity of resources was left out. 3.1.4 Publication and dissemination The project report will be published by the Author and then a copy will be forwarded to Kyambogo University, others copies shall be given to Kampala city council and other Public libraries. Soft copies will be converted to PDF, to prevent any distortion of the document.


58

59

4.0

Results and discussion

The section gives the results that were obtained from the data that was collected. The detailed analysis and design is found in Appendix A 4.1

Traffic

The ADT of the Project road was found to be 1,116 Vehicles/day.

Summary of Traffic data 0% 1% 1% 0% 8%

43% 26%

Motorcycles Saloon Cars Small bus Small truck Large bus

21%

Medium truck(2 Axles) Heavy trucks (3 Axles) Heavy trucks (4 Axles)

The Ministry of Works and Transports’ criterion for upgrading a road in an urban setting is when the ADT is over 300Vehicles per day; hence the road is due for upgrading. From the above summary, Motorcycles take up the greatest percentage of the Traffic, this shows that a Cycle lane will be required.


59

Horizontal alignment Data

4.1.1

60

Horizontal alignment Data

Geometric characteristics of the existing roads’ horizontal and vertical alignments were ascertained from the topographic field surveys undertaken. Circular curves for the existing road are summarised in the table below .The tables below give horizontal alignment data results Table 4. 1 Circular curve data Existing radius Proposed Radius Proposed Design Speed 100 80 50 100 60 50

S/N

From

1

0+027.94

0+035.131

To

2

0+099.832

0+108.656

3

0+243.678

0+346.957

70

100

50

4

0+465.355

0+473.21

110

100

50

5

0+913.381

0+926.273

90

150

50

Super Direction coefficien elevation ofLHS turn t of 3 0.16

3 3 3 3

RHS

0.16

LHS

0.16

RHS

0.16

RHS

0.16

Table 4. 2: Transition curve data

S/N

To

Transition in

Transition out

Direction of turn

1

From 0+010.264

0+027.904

42

42

LHS

2

0+35.131

0+052.771

42

42

LHS

3

0+82.192

0+099.832

42

42

RHS

4

0+108.656

0+126.296

42

42

RHS

5

0+226.038

0+243.678

42

42

LHS

6

0+346.954

0+364.597

42

42

LHS

7

0+447.715

0+465.355

42

42

RHS

8

0+473.721

0+491.361

42

42

RHS

9

0+908.155

0+913.381

28

28

RHS

10

0+926.275

0+931.499

28

28

RHS

From the results above, the existing radius was inadequate except for section 0+465.355-0+473.21.The minimum radius for the project road should be 100m according to the Uganda Roads Design Manual; see Appendix C, Table 2.5.The existing radius was then upgraded to 100m minimum. Going beyond the minimum would involve a lot of compesation, hence both safety and economy were considered in the design. See Appendix I-1 and I-2 for alignment drawings. Transition curves were introduced to counter the effect of centrifugal acceleration because of the minimum radius that was proposed. The Uganda road design manual states that when the radius of the curve is less than V3/432, a transition curve would be required; hence they were cated for as shown in table 4.2 since all the curves didn’t fulfil the condition.


60

Vertial alignment Data

4.1.2

61

Vertial alignment Data

Table 4. 3: Grade data 1

From 0+000

0+400

Existing Gradient(%) 4.25

2

0+400

0+660

10.38

8.42

3

0+960

1+135

8.748

5.43

S/N

To

Proposed Gradients(%)

Terrain type

Rolling Rolling Rolling

3.89

Section 0+400-0+600 had a grade of 10.38%, and according to the Uganda road design Manual, the project road should not have a grade of more than 9%.other grades were chosen so as to balance cut and fill. on section 0+720-1+100,fill was about 5m,which is unrealistic, reducing the fill meant having a very short sag length which would not be adequate for a design speed of 50Km/hr.At this section, the fill could be reduced and speed at that section be reduced to about 30Km/hr. Table 4. 4: Vertical curve data

1

PVI Station PVI Elevation Curve Length(m) Provided Type of Curve 0+434.774 1184.157 45.287 Crest

2

0+791.189

S/N

1154.164

166.188

Sag

Kmin

Standard

10

9-10

12

11-12

Minimum K value at crests = 9, based on or stopping sight distance Minimum K value at sags = 11, based on head light sight distance, rider comfort Crossections Table 4. 5: Crossectional data

Roadway Width (m) Carriageway Width (m) Reserve Width (m) 7.6

5.6

15

Shoulder(m) 1.5

Cycle lane(m) 2

The road is a double lane; two directional flow traffic having a lane width of 2.8 and a total carriageway width of 5.6m as per table 2.2 Appendix B,using the Uganda road design manual as the standard. Shoulders have been limited to 1.5 m wide. Longitudinal gradients of 0.64% to 8% were allowed for vertical alignments in order to enable drainage in the longitudinal direction. Cross section gradient of 2.5% and 4% have been proposed to allow drainage of the carriage way and shoulders respectively. See a Typical cross section in Appendix I-10.Crosssections that were generated are in Appendix I-4 to I-9.


61

Drainage Design

4.2

62

Drainage Design

Design standards Drainage design is consistent with specifications and guidelines of MoWT Manual. The Rational Method was used and assumed uniform rainfall intensity over the entire catchment area, which is a reasonable assumption for smaller catchments. A storm water drainage network was designed with channel depths generally controlled by the road grade. The drainage system comprises of trapezoidal drainage channels with side slopes of 1 in 4. Drainage channels shall be lined with grouted stone pitching of cement mortar ratio 1:4. Two lines of 600mm Culvert shall be installed being influenced by outlet control, This means flooding is mostly likely to take place at the outlet end of the culvert, and hence the people near the outlet will need relocation. A Trapezoidal channel was designed, with base with of 0.5m, 0.6m height and 0.1m free board at a slope of 8.4%.


62

Pav ement Design

4.3

63

Pav ement Design

Defining uniform section Tabulating the CBR Values at each road cross section and selecting its design CBR Table 4. 6: CBR, results Chainage

CBR% LHS

CL

Design CBR

Subgrade Class

RHS

0+000

41

18

18

S5

0+500

10

25

10

S4

1+100

26

15

15

S5

From the table the lowest value obtained is 10% at section 0+500, according to TRL; 1993.The subgrade should have a CBR of at least 15%.this section will be cut away and replaced with fill that has a CBR of more than 15%. Table 4. 7: Design of Earth Work Section No

1

Uniform Section

Length

Subgrade stregth

Start

( Km)

class

0+00

End

0+500

0.5

S5

Traffic class

T3

2

0+500

0+900

0.4

S4

T3

3

0+900

1+100

0.2

S5

T3

Materials

Structure

Double Surface dressing Road base:GB1A sub base:Granular Subbase Double Surface dressing Road base:GB1A sub base:Granular Subbase Double Surface dressing Road base:GB1A sub base:Granular Subbase

A Double surface dressing layer was proposed for durability purpose Material on most roads and road sections was found suitable for road construction works after stripping. The PI was found to be 20 and 1.24 Which is Ok Maximum PI of 25% is recommended to be compacted in layers not exceeding 250 mm to 95% MDD as per the AASHTO guide. Subgrade material was recommended to conform to section 3600 of MOWT standards for roads and bridges. As shown in the table. Table 4. 8: Natural gravel requirements

Material Properties CBR(%) bs 1377;part 4

Material Class G15 G7 G3 Minimum 15 ater 7 after 4days soaking soaking,measured at v90% of MDD of 4days soaking BS-Heavy Compaction

CBR-Swell

Maximum 1.5

Maximum 2

Maximum 2

Plasticity index

Maximum 25

Maximum 30

(No requiremet)

Max.Particle size BS1377 Part 2 Maximum Layer Thickness

1/2 of compaacted layer thickness but not> 50mm 250mm compacted thickness placed in one operation


63

Surface dressing

64

A Sub base of 150 mm thick granular material compacted to about 97% MDD based on AASHTO is recommended. A minimum soaked CBR of 30% and a grading modulus of not less than two is specified for base material. Sub base material was recommended to conform to section 3700 of MOWT standards for roads and bridges. Base A base of 175 mm and 200mm compacted to 97% MDD based on AASHTO was recommended. The supervisor on site shall ensure that the minimum CBR value recommended by the design consultant is attained. Surface dressing The following material should be used for surface dressing as per section 4300 of MOWT standards for roads and bridges. Primer of MC 30 cutback bitumen complying with BS EN 1251:200 Aggregates consisting of crushed rock or river sand with 100% passing the 6.3mm sieve and not more than 10% passing 2.36mm sieve. Bitumen of 80/100 shall be used at a spray rate of 1.229kg/m2 and 0.949kg/m2 for the first and second layer respectively. Aggregate sizes of 14/20 mm sprayed at first seal and Aggregate size of 6/10mm for second seal sprayed at a rate of 13.367kg/m2 and 9.548kg/.m2respectively. A double seal was recommended for durability to avoid early development of potholes Material selection The criterion is dependant on the results from the laboratory, the results were compared with specifications, and materials are them accepted, modified or rejected in accordance with the minimum requirements. Aggregate tests were carried out on Kangulumira quarry and were as follows, Table 4. 9 Grading of aggregates from kangulumira quarry Sieve Sizes Percentage passing the sieves Grading limits 28 20 14 10 6.3 2.36 0.075 Flakiness Index(%)

14mm -

20mm 100

14mm -

100 96 26 1 0 0

99 15 0 0 0

100 85-100 0-35 0-7 0-2 0-1

23

24

20mm 100 85-100 0-35 0-7 0-2 0-1

25 maximum


64

Surface dressing

65

Table 4.10 Aggregate properties Results

Test

BS LIMITS:812:19 90 Kangulumira Quarry

Agregate Crushing Value (%)

24

21 Maximum

Aggregate Impact Value (%) Los Angeles Abrasion Value (%)

15

25 Maximum

24

28 Maximum

Water Absorption (%) Bitumen Affinity(% of coated Surface)

0.4

2 Maximum

>95

>95 Maximum

The results were found to conform, hence accepted.


65

66

5.0

Reflections

Challenges Physical planning was poor, there was little maneuver for vehicles, compensation would be very expensive in having the best possible alignment. The project road has no detours, alternative routes while constructing the pavement. Positioning culverts was very difficult since it was an already built up area, water couldnt be channelled into peoples houses. The project road had no defined drains and outflows to plan for an appropriate drainage system. Some tests carried out on borrow material did not conform to the standards yet materials are not readily available, The time allocated to the project was not enough, many aspects such as cost benefit analysis was not done. Lessons learnt The project becomes more elaborate as it proceeds before undertaking a project one needs to have the general layout from the beginning. Some times designs need to be compromised, hence human judgement is always necessary. Many unforeseen activities come as the project is preceding, hence a need to cater for any contingencies in the budget.


66

67

6.0

Conclusions and Reccomendations

Conclusions The ADT of the Project road was found to be 1,116 Vehicles/day., with 43% of the traffic being motorcycles. The project Road was found to be a class C Gravel and was being upgraded to class (iii) bitumen. The terrain was found to be rolling with a transverse slope of approximately 10%. Re alignment at section 0+800 has been proposed due to the increase of the radius. Carriage way is with of 5.6m, 1.5m shoulders, cycle lane of 2m has been proposed. A Trapezoidal section of 0.5m bottom with, 1.21 m height, side slopes1:2 and 1:1.5 and Cross culverts of 600mm. The subgrade at section 0+500 is unsuitable and a replacement was proposed. The pavement is composed of double surface dressing, road base175mm, 200mm, and 175, subbase, 100mm, 200mm, and 100mm respectively for the three sections. The chipping spray rate is 13.367kg/m2 and 9.548kg/m 2 for first and second layer respectively and binder at a rate of 1.229kg/m2 and 0.949kg/m2 respectively for 1 st and second layer respectively. Curves were based on stopping sight distance and Overtaking will be marked by straight lines. A hump will be placed at chainage 0+010 to avoid accidents and other Speed limit signs especially at the sag.


67

Conclusions

68

Recommendations Cycle lane should be provided to enable cyclist not to interfere with the motorized traffic. Humps should be provided at section 0+010 to counter the effect of the reverse curve. A well organized settlement plan should be done so that peaceful vacations take place. Quality control should be ensured especially for materials in according to the specifications stipulated. The field supervisor should ensure that the required compaction s achieved. Drains should be cleaned regular to a void any silting that may lead to blockage and hence flooding. Since the grades are steep, scour checks are necessary and should be designed for.


68

Bibliography

69

Bibliography 1) Arora, K.R,( 2002)Soil Mechanics and Foundation Engineering 2) Bindra, S.P. (1999). A course in Highway engineering 4thEdition, Dhanpat rai publishers, New Delhi 3) CIA. (2008, December 23/02/2010). World Statistics,Country Comparisons. Retrieved February 23, 2010, from Natioon master: WWW.nation master.com 4) Kadiyali, R,L. (1996). Principles and practice of Highway Engineering. New Delhi: Khanna Publishers. 5) Kiely, G. (1997). Environmental Engineering. Berkshire,England: McGraw-Hill Publishing Company. 6) MoW&T. (1994). Geometric design Manual. Kampala. 7) Ministry of Works, Housing and Communications.(2004) General Specifications for Road and Bridgeworks 8) Ministry of works, housing and communication,( 2004) District Road works Technical manual, volume 1 9) Ministry of works, housing and communication .Uganda road design manual January 2004 10) Ministry of works, housing and communication .Uganda road drainage manual January 2005 11) Ministry of Works and Transport (2004). Geometric Design Manual. Kampala: Republic of Uganda 12) O'Flaherty, C. (2002). Transport Planning andTraffic Engineering,3rd Edition. London: Butterworth-Heinemann. 13) Okello F.E (2009). Highway Engineering I and II.Lecture notes, Department of Civil Engineering Kyambogo 14) Paul H. W and Radnor J.P. (1967).Highway engineering 4e 3rd Edition, John Wiley and sons 15) SATTC, (2000)geometric Design Manual, 16) SANRA,(2000),geometric design manual 17) Singh, J. (2004). Highway Engineering, Fifth Edition. Delhi: Bhargave Laser Printers 18) Transport Road Research Laboratory,(1993)Guide to design of Bitumen surfaced Roads in Tropical and subtropical countries, Overseas Road note 31,Crowthorne,England 19) Transport Road Research Laboratory,(1993)geometric design manual Overseas Road note 6,Crowthorne,England 20) Thagesen, B. (1996). Highway and Traffic Engineering in Developing Countries (1st Edition ed.). Great Britain: Alden Press. 21) Brockenbrough &Boedecker,(2004),Highway Engineering Hand book, Mc Grawhill


69

70

Appendices


70

71

Appendix A, Analysis and Design A.1 Traffic Construction period (n) is assumed to be 2yrs Design life=15years One station was considered Determination of cumulative design traffic, T n

T = ∑Ti i =1

Ti = 365× F ×W ×G ×Y × 10−6 F = Unidirectional traffic flow

Assuming a 1:2 directional split

F=

2 (Of the traffic volume of each class) 3

For example minibus;

2 Fo = × 723 3 = 482 Vehicles/day Fp=482(1-1.9)2 =390 Vehicles/day Wear Factor, W 4.5

Axleload,in tons  W =   inesa 8.16  For small buses

1.00  W =   8.16 

4.5

1.00  +   8.16 

4.5

W = 0.0001 + 0.0018 =0.0019 esa ©Final Year Individual project, Upgrading Nsambya-Kirombe road to a bituminous paved surface. Kyambogo University, Kampala Uganda 2009/10

71

A.1 Traffic

72

Growth factor G G= (1+0.06)0.5(15) 7.95 Results See tables of results in the appendix D From the table a cumulative design traffic of 1.471 msa was obtained which correspond to a Traffic Class of T3 i.e. 0.7<1.4710<1.5


72

Appendix A.2: Geometric design

73

Appendix A.2: Geometric design Summary of adopted design parameters and standards Design Speed =50km/hr Standard, Uganda road design manual Minimum radius = 100m; according to Derived from formula,

VD2 R min = 127(e+ f) Where: VD = Design Speed (km/h) e = Cross fall of road or the maximum super-elevation (%/) =7% f = Coefficient of side friction force developed between the vehicles and road Pavement Minimum length of transition curves = 50m; based on

L=

0.0702V 3 Where: RC

L = minimum length of spiral (m) V= Design Speed (km/h) R = Curve radius (m) and, C= rate of increase of centripetal acceleration (m/s3), in this C = 1 Transition curves were provided where radius of horizontal curves was less 289.35m obtained from R <

V3 =for the project road, the required minimum radius for the 432

project road was R <

503 = 289.35m 432


73

A.3 Drainage Design

74

A.3 Drainage Design Design standards Drainage design is consistent with specifications and guidelines of MoWT Manual. The Rational Method was used and assumed uniform rainfall intensity over the entire catchment area, which is a reasonable assumption for smaller catchments. Design of longitudinal drainage structures. A storm water drainage network was designed with channel depths generally controlled by the road grade. The drainage system comprises of trapezoidal drainage channels with side slopes of 4:1. Drainage channels shall be lined with grouted stone pitching of cement mortar ratio 1:4. a) Q=

Estimation of design flood flows CIA 3 m /s 3.6

C =Runoff Coefficient I =Rainfall intensity (mm/hr) A = Catchment Area (in km2)

Estimation of runoff coefficients C = 1.00 *(CS = CK = CV ) 1.00 *(0.08 + 0.08 + 0.21) = 0.37

(Uganda road design Manual,2005)

Estimation of intensity Intensity of rainfall in an area id dependant on the duration of the storm. its assumed that that at peak flow the duration is equal to the time of concentration.

 0.87 × L3  =   H 

0.385

0.87 × 0.83  =   48 

0.385

=9.9 Minutes Where ©Final Year Individual project, Upgrading Nsambya-Kirombe road to a bituminous paved surface. Kyambogo University, Kampala Uganda 2009/10

74

A.3 Drainage Design

75

L=length of longest water course from exit (in km) H= height from source to exit (in m) From the topographical map L=800m measured from project road to exit H=1200-1152 =9.9 minutes =48m From the intensity-duration frequency curves for Kampala provided, the intensity for a 5year return period is given by IS=110mm/hr See Appendix E-2 Estimation of the catchment area, A Considering an offset of 200m from the road, Area A1 (For the surrounding Areas) =0.2×0.8=0.16km2 Carriage way area Area A2= 7.6/2×0.8 =3.04×10-6 Km2 Peak runoff Total area= (0.16+3.04×10-6) =0.16km2 Peak discharge

Q=

0.37 × 0.16 × 110 3 m /s 3.6

=1.81m3/s Hydraulic design of longitudinal drains Design parameters Design discharge

Q=1.81m3/s

Permissible velocity=3m/s Base material

stone masonry


75

A.3 Drainage Design

76

Determination of area, A A=

Q 1.81 = = 0.603m2 V 3

Determination of channel depth, d Assuming a bottom width of 0.5m, and a fore slope of 1:.2, side slope of 1: 1.5 as specified by Uganda Road Design Manual section 7 table 7.4 Controlled by the road grade. The drainage system comprises of trapezoidal drainage Slope 1 st section, 8.42% From Manning’s formula, V =

R=

1 2/3 1/2 R S n

Cross sectional area Wetted perimeter

Taking a velocity of 2m/s,n=0.024 for stone masonry Vn R =  1/2   S 

2/3

2 × 0.024  R =   8.421/2 

2/3

=11.12 -let d be the depth of the channel. Top width=3.4d+.5 Area=1/2d (3.4d+0.5+0.5) =0.603 d=0.466 Ministry of works and housing recommends 0.1m for free board Depth of the trapezoidal Channel=0.566m Nature of Bed=stone masonry Side Slope= fore slope1; 2and1; 1.5 side slope Channel Slope=8.4% Minimum gradient for longitudinal drainage=0.5 Bed Width=0.5m Channel Depth=0.566m Freeboard, Fb=0.1m


76

A.3 Drainage Design

77

0.1m 1

0.6m

1

1.5 2 0.5m

Design of cross drainage structures Design parameters Runoff coefficient C=0.37 fro appendix Considering a return period of 10yrs From the intensity duration curve, I=123mm/hr Catchment area 160000m2 0.16km2 Determination of peak discharge Using rational formula

Q=

CIA 3 m /s 3.6

Q=

0.37 × 123 × 0.16 3 m /s 3.6

Q = 2.022

Hydraulic design of a typical culvert using a Monograph Basic design data Cross sectional Culvert Area A=Q/V A=2.022/3 =0.674m2 Trial determination of number and size of pipe culverts


77

A.3 Drainage Design

78

Preliminary sizing Culvert sizes (mm) Culvert size Areas 600 0.2827

Number of culvert lines Remarks 2

900

0.6362

2

1200

1.131

1

Design discharge 0.674/2 =0.337m3/s Length of culvert=15m Slope of culvert=2% Check for inlet and outlet control Checking for inlet control Headwater depth using inlet control From the graph in appendix E-3 HW/D=1.38 Allowable headwater to depth ratio, HW/D=1.5, hence within limits HW=0.8m Outlet control Tailwater depth, TW=1.2 Free board, Fb=0.45 Entrance type= grooved end with squared edge inlet Pipe Culvert groove end with headwall Concrete box culvert wing wall flare of 30-75 degrees


78

A.3 Drainage Design

79

Headwater depth .HW using outlet control. Head loss for box culvert flowing full Head water under outlet control is given by; HW=H+ho-LSo H=0.16 (from figure) Vertical distance from culvert invert to hydraulic grade line, ho ho=1/2(critical depth +D), Tailwater depth whichever is greater. =1/2(0.4+0.6), TW=1.2 =0.5, TW=1.2 =1.2 ho=1.2 HW=0.44+1.2-15×0.02 HW=1.34 HW water at the outlet is greater than that at the inlet, hence the culvert flows are being controlled by outlet control. Flow Properties Discharge Velocity(Vm/s) 3

Q(m /s)

1.18

3

Crosssectional Manning 2 Coefficient(n) Area(Am )

1.21

0.024

Depth of drains(hm)

0.6

Bottom Top Width(Wm) width(Lm)

0.5 2.6m


79

A.3 Drainage Design

80

Measurement of subgrade strength Project area is classified as category 2 according to ORN 31 because it has with deep water tables and where rainfall is sufficient to produce significant changes in moisture conditions under the road. The rainfall in this area is usually greater than 250 mm per year and is often seasonal Using DCP machine the subgrade was assessed see Appendix for DCP charts Testing subgrade soils Subgrade strength was considered at a depth of 475 Defining uniform section Tabulating the CBR Values at each road cross section and selecting its design CBR From the table the lowest value obtained is 10% Design of earthworks Road base=175mm Sub base=100mm Design of surface dressing Design data ADT (All vehicles) =1116Vehicles/day ADT (Commercial vehicles) =508 Vehicles/day Type of binder

Penetration grade bitumen 80/100

Type of chippings

Cubical

Existing surface:

First layer Primed road base


80

A.3 Drainage Design

81

Second layer; Lean bituminous Climatic conditions tropical Recommended size of Chippings From table the surface hardness is Normal Traffic category is category one from table Number of commercial vehicles per lane= 508/2=254vehicles This traffic is in the range 200-1000 category 3 Average least dimension From table …., since the surface hardness category is Normal and traffic category is 3 Recommended size of chippings is First layer=14mm Second layer=0.5(14) =7mm Since it’s not on the Market, 10 mm shall be adopted. Chipping size 14 10

Median sieve grading(mm) Flakiness Index 14 23 10 24

Chipping spread rate Determination of Average least dimension Median sieve size=14mm and 10mm and flakiness index is=23 and 24 From figure ALD=9.8mm and 7mm Surfacing Layer

Chipping sizes ALD(mm)

First layer Second layer

14mm 10mm

9.8 7

Chipping application rate (Kg/m2) =1.364*ALD First Layer=1.364×9.8=13.367Kg/m2 Second Layer=1.364×7=9.548Kg/m2 Basic binder spread rate R=0.625+ (F*0.023) + [0.0375+ (F*0.0011)] ALD ©Final Year Individual project, Upgrading Nsambya-Kirombe road to a bituminous paved surface. Kyambogo University, Kampala Uganda 2009/10

81

A.3 Drainage Design

82

Where F is the overall weighting factor ALD = the average least dimension of chippings (mm) R=Basic rate of spread of bitumen (Kg/m2) From table, first layer F=7, ALD=9.8 R=1.229(Kg/m2) Second layer F=2, ALD=7 R=0.949(Kg/m2) Adjustments of spray rates in accordance with ORN 3(TRL, 2000) R*0.99 First layer, =1.2167 Kg/m2) Second layer=0.9395


82

Appendix B:Tables

83

Appendix B:Tables Table: 1.1: Highway Length Statistics Paved highways Total highway length Country Length(km) Country Length(km)

Un Paved highways

United States

6,406,296

United States

4,148,395

Country States

Length(km) 2,257,902

India

3,319,644

India

1,517,077

India

1,802,567

Brazil

1,724,929

France

894,000

Brazil

1,630,058

Canada

1,408,800

Spain

657,157

China

1,088,494

China

1,402,698

Japan

534,471

Canada

911,494

Japan

1,161,894

Canada

497,306

Japan

627,423

France

894,000

Italy

479,688

Australia

497,513

Australia

811,603

U.K

371,913

South Africa

288,593

Spain

663,795

Russia

358,833

Turkey

254,734

Russia

532,393

China

314,204

Mexico:

221,445

Italy

479,688

Australia

314,090

Bangladesh

187,713

Turkey

385,960

Poland

249,060

Indonesia

184,030

U.K

371,913

Germany

230,735

Russia

173,560

Poland

364,656

Austria

200,000

Philippines

159,575

South Africa

362,099

Sweden

166,523

Argentina

152,123

Indonesia

342,700

Ukraine

163,898

Pakistan

145,014

Mexico

329,532

Indonesia

158,670

Nigeria

134,326

Pakistan

254,410

Turkey

131,226

Poland

115,596

Germany

230,735

Belgium

116,687

Hungary

106,523


83

84

Appendix B:Tables

Figure 1.1: Highway location process

Table 1.2: Ongoing and proposed projects by 2013 No.

Road Sections

Length

No. Road Sections 1 Masaka-Bukakata

Length

1 Kabale-Kisoro-Bunagana/Kyanika(on-going)

98 km

2 Gayaza-Zirobwe-Wobulenzi(on going)

67 km

2

Atiak-Moyo

36 km

3 Soroti-Dokolo-Lira(on-going)

123 km

3

Kyenjojo-Hoima-Masindi-Kigumba

238 km

4 Fort Portal-Bundibugyo-Lania

135 km

93 km

103 km

4

Mpigi-Maddu-Ssembabule

5 Matuga-Semuto-Kapeka

42 km

5

Tirinyi-Pallisa-Kumi/Pallisa-Mbale

69 km

6 Hoima-Kaiso-Tonya

78 km

6

Mbale-Bubulo-Lwakhakha

41 km

7 Busega-Mityana

57 km

7

Namagumba-Budadiri

30 km

Mbarara-Kikagati

35 km

Rukungiri-Ishasha

21 km

8

9 Muyembe-Moroto

191 km

9

10 Kapchorwa-Suam

77 km

11 Gulu-Atiak-Bibia

104 km

8 Kampala Northern By Pass(dualling)

12 Mirama-Hills-Ntungamo/Kagamba-Ishaka Total Length

94 km 1,055 km

10 Rwenkunye-Apac-Lira-Kitgum

50 km 230 km

11 Mukono-Kyetume-Katosi/Kisoga-Nyenga

72 km

12 Kamuli-Bukungu

64 km

13 Villa Maria-Ssermbabule Total length

48km 1,141 km


84

Appendix C: Geometric Design tables

85

Appendix C: Geometric Design tables Table 2. 1: Division into road category Road Category Description Category A Principle Arterial System (Primary Roads)

Category B

Minor Arterial System (Secondary Roads)

Category C

Collectors

Category D

(Tertiary Roads) Local Road System (Feeder Roads)

Function Desired Rural Speed Limit Connection between the national road system and those of neighbouring countries Linkage between the provincial capitals, main centers of 100km/hr population and production centers Connection between local centers of population Linkage between districts, local centers of population and 80km/hr development areas with the principal Arterial System Linkage between locally important traffic generators and their rural hinterland Provision of service to smaller communities 80km/hr Provision of access to land adjacent to the collectors system 80km/hr

Source: MoW&T, 2005 Table 2.2 Division into road class Class

Capacity

Category

10 pcu/d I Bitumen 10 – 6 II Bitumen 8 – 4 III Bitumen 6 – 2

Roadway Carriageway Reserve Maximum Design Speed Width (m) Width (m) Width (m) (km/hr) Level Rolling Mountainous 11 7 40 110 100 80 9 6 30 90 80 60 7.6 5.6 25 80 70 50

A Gravel B Gravel C Gravel

9 7.6 6.4

A,B A,B,C B,C

3

8–4 6–2 4–1

6 5.6 5

30 25 15

90 80 60

80 60 50

70 50 40

A A,B A,B,C

Source: MoW&T, 2005

Design Vehicle type

Symbol

Height

width

Length

Front

Rear

Overall (m)

Overhang (m)

Wheel base (m)

Table2.3 Design Vehicle characteristics Minimum design Minimum turning radius inside radius (m) (m)

4 x 4 passenger car

DV-1

1.3

2.1

5.8

0.9

1.5

3.4

7.3

4.2

Single unit truck

DV-2

4.1

2.6

9.1

1.2

1.8

6.1

12.8

8.5

Single unit bus

DV-3

4.1

2.6

12

2.1

2.4

7.6

12.8

7.4

Semitrailer combination large DV-4 Interstate Semitrailer DV-5

4.1

2.6

17

0.9

0.6

6.1 & 9.1

13.7

5.8

4.1

2.6

21

1.2

0.9

6.1 & 12.8

13.7

2.9

Source: MoW&T, 2005 Table 2. 4 Terrain classification Type of Terrain

Description Level or gently country which offers few obstacle to the construction of a road having continuously Level (or Flat) Terrain unrestricted and vertical alignment (transverse terrain slope around 5%) Rolling, hilly or foothill country where the slopes generally rise and fall moderately gently and where occasional steep slopes may be encountered. It will offer some restrictions in horizontal and vertical Rolling Terrain alignment. (20% • transverse terrain slope > 5%) Rugged, hilly and mountainous country and river gorges. This class of terrain imposes definite restrictions on the standard of alignment obtainable and often involves long steep grades and limited sight distance Mountainous Terrain (70% • transverse terrain slope > 20%) In addition to the terrain class given above, a fourth class is added to cater for those situations whereby the standards associated with each of the above terrain types cannot be met. Escarpment situation are where it is required to switchback road alignment or side hill traverse sections where earthwork quantities are huge Escarpment (transverse terrain slope > 70%)

Source: MoW&T, 2005


85


86

Table 2. 5: Design Parameters

Design Element Design Speed Min. Stopping Sight Distance Min. Passing Sight Distance Min. Horizontal Curve Radius Max. Gradient (desirable) Max. Gradient (absolute)

Flat Rolling 80 70 115 95 545 485 240 185 4 5.5 6 7.5

s 50 60 345 85 9 11

Urban 50 60 345 100 9 11

% %

0.5 7

0.5 7

0.5 7

0.5 4

Crest Vertical Curve stopping

Kmin

32

22

9

9

Crest Vertical Curve passing

Kmin

310

246

126

126

Sag Vertical Curve stopping

Minimum Gradient in cut Maximum Superelevation

Unit km/h m m m % %

Kmin

25

20

11

11

Normal Cross fall

%

2.5

2.5

2.5

2.5

Shoulder Cross fall Right of Way Source: MoW&T, 2005

% m

4 50

4 50

4 50

4 30

Table 2.5.1: DesignParameters

Design Maximum Speed e [%]

Limiting value of f

(e/100 + f)

Calculated Rounded Radius Radius

30

4

0.17

0.21

33.7

35

40

4

0.17

0.21

60

60

50

4

0.16

0.2

98.4

100

60

4

0.15

0.19

149.2

150

70

4

0.14

0.18

214.3

215

80

4

0.14

0.18

280

280

90

4

0.13

0.17

375.2

375

100

4

0.12

0.16

492.1

490

110

4

0.11

0.15

635.2

635

0.09

0.13

872.2

870

120 4 Source: MoW&T, 2005


86


87

Appendix C-1, Survey Data P 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43

N

E

Z

1000 1034.0818 1036.992 1038.3323 1039.6222 1040.563 1030.2434 1032.5092 1009.4007 1011.0875 1006.9668 1003.5653 974.66311 975.66212 976.10168 976.59261 972.86447 972.48361 942.91454 944.15179 940.49614 939.95398 967.49454 969.94883 963.83917 970.43073 972.69084 968.28536 948.64966 905.0099 906.38003 906.8524 902.34864 902.25524 933.41229 917.00298 885.9431 887.60202 889.23831 884.08451 883.16878 882.43435 822.00906 900.83075

1000 969.68989 972.08965 972.94227 974.9438 977.04066 967.04386 963.80642 989.37063 993.40625 987.02167 998.71451 1002.9668 1005.9304 1007.0975 1008.7232 1000.4925 999.55399 1019.3319 1020.6395 1016.5031 1015.5227 1013.0651 1012.468 1013.7621 1025.7908 1025.9257 1026.6823 1010.0397 1046.1101 1048.3275 1050.6138 1043.6989 1042.8815 1033.659 1045.2676 1061.8538 1064.1329 1066.2345 1059.9492 1059.0361 1058.3458 1120.7762 1041.6305

1200 1201.0534 1200.9687 1201.2696 1201.5599 1201.9143 1201.0337 1201.1194 1200.8553 1200.4658 1200.5874 1200.8521 1199.7378 1199.8352 1200.3215 1200.5874 1199.4691 1200.2276 1198.4853 1199.0231 1199.0013 1199.2359 1200.772 1200.9905 1200.8593 1200.6491 1200.7415 1200.6468 1200.2355 1197.5829 1197.5252 1197.7588 1197.644 1197.0978 1199.8349 1198.5082 1196.3314 1196.3332 1196.8535 1196.3305 1196.0431 1196.8931 1192.4627 1198.7751

D P INSTR CL SHLDR DR EP SH SHLDR DR CL SHLDR SHLDR EP CL SHLDR DR SH DR SH CL SHLDR SHLDR PKT2 AC,CL AC,SHDR SHDER C;L AC SHLDR SHLDR BLI CL SH SHDER DR BL1 BL2 CL SHLDR SHLDR SH SHDER DR SH SH CL,AC

44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85

N 898.05307 871.20665 873.38327 876.74533 870.87646 870.52177 846.80788 821.14382 819.70806 806.96942 808.10529 808.47143 809.99911 803.42404 802.86123 802.46671 708.73683 650.10054 649.84223 649.59635 653.52554 654.97292 655.04934 655.37635 679.2749 650.89688 627.10481 630.11321 623.99187 625.26347 617.98404 582.37554 580.77739 687.90591 686.48081 685.78362 685.19702 688.23511 688.59641 688.83673 629.79903 628.8962

E 1043.6786 1075.0443 1077.194 1077.9974 1071.8225 1071.2467 1088.5542 1107.6647 1123.4663 1122.6014 1125.0642 1126.9041 1131.1654 1121.2061 1120.4879 1119.1487 1089.881 1074.6985 1077.5094 1078.69 1081.0063 1071.809 1070.7626 1069.7544 1085.8976 1081.0515 1064.2543 1064.9225 1063.4201 1059.036 1072.6721 1056.7203 1058.5472 1083.9093 1085.3129 1086.438 1087.4992 1081.21 1080.1685 1079.5109 1054.8296 1057.1482

Z 1198.2902 1196.1512 1196.1116 1196.9603 1196.2956 1195.932 1194.9073 1194.0409 1193.4457 1192.1321 1191.9086 1192.2471 1192.3933 1192.0288 1191.7436 1192.6337 1185.2181 1182.2929 1182.3142 1182.2834 1183.073 1182.5663 1182.209 1183.2053 1184.2392 1183.1011 1181.2118 1181.3721 1180.934 1180.9387 1180.6088 1177.1594 1177.1025 1184.2608 1184.3099 1184.1474 1185.2722 1183.9822 1183.8476 1184.5358 1179.3664 1179.444

D SHLDR CL,AC BL1 SHLDR DR EP BL2 EP BLI CL,AC SHLDR SHLDR SHLDR SHLDR DR SHLDR SHLDR CL,AC SHLDR DR SH SHLDER DR SH BL1 BL2 AC,CL SHLDER SHOLDER SH ACESS,CL CL,AC SHLDER CL SHLDER DR SH SHLDER DR SH CL/CORNER SHLDR


87


88

Appendix C-1, Survey Data 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123

628.38323 631.23584 631.9292 660.97162 649.08148 631.39236 625.56893 621.99688 576.71937 570.02185 564.52891 620.73524 588.72474 587.09663 538.25884 526.78774 522.1137 520.40723 517.54871 520.5866 504.48151 503.26452 503.1895 503.16366 506.22315 506.04833 484.13637 486.77862 476.56129 450.86409 450.14054 449.83069 448.66531 450.36545 416.84319 416.35655 415.91508 416.41479

1058.0736 1052.673 1051.642 1075.4763 1069.3792 1062.2258 1059.7729 1058.9199 1029.9837 1030.8325 1029.1094 1047.9284 1041.8412 1038.9819 1023.4335 1030.6081 1030.4653 1034.0306 1028.2374 1017.8943 1019.2943 1021.1308 1021.9667 1024.4536 1017.5582 1015.7683 1021.1648 1010.5824 1007.5071 1007.4185 1009.4559 1010.6317 1012.2405 1005.0761 999.92797 1002.3037 1003.6687 998.54499

1179.5282 1179.0277 1179.2702 1183.684 1182.3168 1180.7275 1179.7132 1179.7766 1175.514 1174.127 1174.2637 1178.4074 1175.5695 1175.296 1171.3299 1172.6647 1171.5228 1171.8257 1171.6333 1170.8123 1168.8417 1168.6584 1168.4633 1170.3813 1169.0088 1169.1915 1167.1333 1167.6869 1166.0871 1160.9188 1160.7677 1160.5926 1161.8998 1160.5131 1156.7366 1156.593 1156.4874 1156.7031

DR SHLDR DR BL1 EP BL2 SH BL1 EP ACCESS EP DR CL SHLDR STATION 5 BL1 ACCESS SH BL1 EP CL SHLDER DR SH SHLDR ACCESS BL2 BL1 BL2 CL SHLDR DR SH SHLDR CL SHLDR DRAINAGE SHLDER

124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171

384.14474 383.78929 384.82383 358.57006 358.41062 359.81641 314.85913 314.41403 315.77324 290.88648 290.29322 290.0302 291.76016 292.0057 250.74614 250.6148 251.55165 252.64555 252.55661 260.83217 248.71386 232.20981 190.36056 190.14551 190.57441 169.06855 147.43081 147.68513 147.39669 120.96264 120.61888 120.579 120.83485 91.717313 91.727439 91.501475 91.964122 90.001579 60.648546 60.190048 59.960075 60.502205 60.618393 29.899876 29.511819 29.299759 -24.80064 -25.39334

993.73255 996.91082 991.90913 987.84058 989.88771 986.1784 979.02918 981.98448 976.02772 973.66056 976.49025 978.12377 971.45188 969.68785 967.67253 970.57751 964.16076 972.15505 975.05074 974.15087 971.81568 969.24081 958.26151 960.81719 955.70354 952.40919 958.10728 960.19574 956.80747 958.87821 957.38752 957.12797 956.79301 956.4141 958.98728 960.36453 953.85335 953.13076 952.93228 954.72646 955.99523 950.59666 949.89731 949.71522 947.74661 946.88279 944.07218 948.38004

1155.3752 1154.7212 1155.4475 1154.795 1154.7968 1154.8184 1154.6533 1154.7393 1154.5024 1154.9452 1154.862 1154.994 1154.8921 1154.8919 1155.4085 1155.3479 1155.4637 1155.4336 1155.2589 1155.8083 1155.6583 1150.8747 1037.6383 1157.9511 1153.6539 1154.4312 1160.4133 1160.5452 1162.3489 1161.5109 1161.4828 1161.7247 1162.4035 1162.0508 1165.2259 1165.2533 1165.118 1165.4508 1167.596 1167.6263 1167.6525 1167.616 1167.4529 1170 1169.8289 1170.2232 1173.2051 1173.1405

CL SHLDER DR CL SHLDR DR CL SHLDR SHLDR CL SHLDR SH SHLDR SH CL SHLDR SHLDR ACCESS SHLDR SHLDR

CL SHLDR SHLDR EP CKL SHLDR SHLDR SHLDR SHLDR

CL SHLDR SH SHLDR ACESS,CL CL SHLDR DR SHLDR DR CL SHLDR SH CL SHLDR


88


89

Appendix D: Pavement Design Appendix D-1, Traffic class Vehicle Category

Wear Factor (W) F W G Y Ti Front Axle Rear 1 Rear 2 Rear 3 Rate Fo Fp (esa) yrs (msa) (esa) (esa) (esa) (esa) r % veh/dayveh/day 0.0001 0.0018 0.0000 0.0000 -1.9 482 464 0.0019 0.8660 15 0.0041 0.0001 0.0018 0.0000 0.0000 6 143 161 0.0019 1.5481 15 0.0025 0.0111 0.2507 0.2507 0.0000 3.6 1 1 0.5124 1.3038 15 0.0026 0.9147 2.4969 0.0000 0.0000 6 17 19 3.4116 1.5481 15 0.5610 0.9147 0.9147 0.9170 0.0000 6 20 22 2.7464 1.5481 15 0.5178 0.9147 2.4969 0.9170 2.4969 6 6 7 6.8255 1.5481 15 0.3830 1.4710 T3

Small bus Small truck Large bus Medium truck (2 Axles) Heavy trucks (3 Axles) Heavy trucks (4 Axles) Cummulative Design traffic(msa) Traffic Class

Appendix D-2: Axle loads % Vehicle class Small bus Small truck Large bus (2 Axles) (3 Axles) (4 Axles)

Gross weight (tons) 3.00 3.00 15.00 18.00 24.00

Front Rear Axle Axle 1 (tons) (tons) 1.00 2.00 1.00 2.00 3.00 6.00 8.00 10.00 8.00 8.00

36.00

8.00

Rear Axle 2 (tons) 0.00 0.00 6.00 0.00 8.00

10.00

8.00

Rear Axle 3 (tons) 0.00 0.00 0.00 0.00 0.00

Motorcycles Saloon Cars Small bus Small truck Large bus Medium truck(2 Axles) Heavy trucks (3 Axles) 10.00 Heavy trucks (4 Axles)

1216 608 723 214 1 26 30 9

43 21.5 25.6 7.6 0.04 0.9 1.1 0.3

Appendix D-4, Traffic Counts 16 hr Counts Category Mon Tue Wed Thu Motor bikes 1153 1094 1211 1174 Cars 448 493 503 433 Small bus 692 654 665 702 213 241 198 203 Small truck Large bus 2 1 0 1 Medium truck (2axle) 24 18 32 24 Heavy trucks (3 axle) 31 26 18 21 Large trucks (4 axles)

10

7

8

24 hr counts Fri Sat 1153 1096

4

403

405

612 196 2

520 178 3

20

15

35

30

9

5

Category 1018 Motor bikes 421 Cars 510 Small bus 188 Small truck 0 Large bus 21 Medium truck (2 axle) 18 Heavy Trucks (3 axle)

Sun

2

Large trucks (4 axles)

Fri 1233 568 785 204 2 23

Sat 1205 512 670 198 3 19

41

34

12

8

Appendix D-3: ADT Day of week

Motobikes Saloon cars Small bus 16hr 24hr 16hr 24hr 16hr 24hr Conv. factors 1.1 1.10 1.41 1.26 1.28 1.29 Mon 1153 1233 448 631 692 888 Tue 1094 1170 493 695 654 839 Wed 1211 1295 503 709 665 853 Thur 1174 1255 433 610 702 900 Fri 1153 1233 403 568 196 251 Sat 1096 1205 405 512 520 670 Sun 1018 1119 421 532 510 657 Total 24hr counts 8511 4258 5058 ADT= T/7 1216 608 723

4 or more Small trucks Large buses 2 Axle trucks 3 Axle trucks Axle trucks Total 16hr 24hr 16hr 24hr 16hr 24hr 16hr 24hr 16hr 24hr 1.04 1.11 1.00 1.00 1.15 1.27 1.17 1.13 1.33 1.60 213 222 2 2 24 28 31 36 10 13 241 251 1 1 18 21 26 30 7 9 198 206 0 0 32 37 18 21 8 11 203 211 1 1 24 28 21 25 4 5 196 204 2 2 20 23 35 41 9 12 178 198 3 3 15 19 30 34 5 8 188 209 0 0 21 27 18 20 2 3.2 1501 9 181 208 62 214 1 26 30 9 2827


89


90

Appendix D-4: Natural moisture content

NATURAL MOISTURE TEST RESULTS Project: upgrading Nsambya Kirombe road Nsambya Location/Source: Student: Byamukama Norman, Soil Description: Reddish Brown BS 1377 : Part 2 :Clause 3 1990 . Test Method : Sample Reference: Sampling Date: 20/03/2010 Testing Date: 23/03/2010

NATURAL MOISTURE TEST RESULTS Project: upgrading Nsambya Kirombe road Nsambya Location/Source: Student: Byamukama Norman, Soil Description: Reddish Brown BS 1377 : Part 2 :Clause 3 1990 . Test Method : Sample Reference: Sampling Date: 20/03/2010 Testing Date: 23/03/2010

TEST DATA Container no. Wet soil +Container Dry soil +Container Moisture Average Moisture Content

TEST DATA

1 2 3 gms 163.5 120 53.5 gms 156.5 114 48 7.00 6.00 5.50 % 6.50

Container no. Wet soil +Container Dry soil +Container Moisture Average Moisture Content

1 2 3 gms 124 119.5 119.5 gms 116 113 111.5 8.00 6.50 8.00 % 7.50

Appendix D-5: Plastic and liquid limit PLASTIC LIMIT AND LIQUID LIMIT (CONE PENETROMETER) Up grading Nsambya-Kirombe road to a bituminous paved Project: surface Location: Nsambya Sample Source: 0+00 Soil Description: Sampling Date: 20/03/2010 Test Method BS: 1377 part 2:1990. Testing Date:

23/03/2010

Plastic Limit

Test no.

1

2

3

Container no. Mass of wet soil + container

1 g

80.50

123.50

125.00

Mass of dry soil + container

g

79.50

122.00

124.00

Mass of container

g

72.50

117.00

118.00

Mass of moisture

g

1.00

1.50

1.00

Mass of dry soil

g

7.00

5.00

6.00

Moisture content

%

14.29

30.00

16.67

1

2

3

Liquid Limit

Average

Initial dial gauge reading

mm

0

Final dial gauge reading

mm

15.2

16 22.3 21.8 23.5 23.5

Cone Penetration

mm

15.2

16 22.3 21.8 23.5 23.5

Average cone penetration

mm

Container no.

15.5

0

0

0

22.05

0

20.32

0

23.50

l

Mass of wet soil + container

g

73.50

79

70.00


g

57.71

36.5

45.10

Mass of container

g

18.00

19.0

18.50

Mass of moisture

g

15.79

42.00

24.90

Mass of dry soil

g

39.71

17.50

26.60

Moisture content

%

39.8

41.6

93.6

41.0

PI=20. ©Final Year Individual project, Upgrading Nsambya-Kirombe road to a bituminous paved surface. Kyambogo University, Kampala Uganda 2009/10

90


91

PLASTIC LIMIT AND LIQUID LIMIT (CONE PENETROMETER) Project: Upgrading Nsambya-Kirombe road to a bituminous paved surface Location: Nsambya Sample Source: 0+500 Sampling Date: 20/03/2010 Test Method BS: 1377 part 2:1990. Testing Date: 23/03/2010 Plastic Limit 1 2 3 Average Test no. Contauner no. Mass of wet soil + container 118.0 125.00 82.50 g Mass of dry soil + container Mass of container Mass of moisture

g g g

116.50 111.50 1.50

123.50 117.00 1.50

81.00 76.00 1.50

Mass of dry soil Moisture content

g %

5.00 30.00

6.50 23.08

5.00 30.00

Liquid Limit Initial dial gauge reading

mm

Final dial gauge reading

mm

Cone Penetration

mm mm

Average cone penetration Container no.

1 0.0

27.69

0.0

2 0.0

0.0

3 0.0

0.0

15.1

16

15.2

21.0

23.9

23.6

15.1

16 15.55

15.2

21 18.1

23.9

23.6 23.75

1

3

Mass of wet soil + container

g

53.20

75.57

2 34.10


g

47.11

65.2

29.70

Mass of container

g g g

22.25 6.09 24.86

26.5 10.38 38.74

14.00

Mass of moisture Mass of dry soil Moisture content

%

24.5

26.8

28.0

4.40 15.70 26.4 PI=1.24

27 26 25

Cone Penetration (mm)

24 23 22 21 20 19 18 17 16 15 14 13 12 22.0

23.0

24.0

25.0

26.0

27.0

28.0

29.0

30.0

31.0

32.0

33.0

Moisture Content (%)

y = 2.169x - 38.23


91


APPINDEX D-6 :DCP field results

92

APPINDEX D-7:DCP field results Dynamic Cone penetrometer (D.C.P) test Chainage 0+500 Layers removed Cone angle 60 surface type zero error Dcp test results On Left Hand Side Initial reading

Dynamic Cone penetrometer (D.C.P) test Chainage 0+000 Layers removed None Cone angle 60 surface type unpaved zero error DCP FIELD TEST results date: 13/03/2010 On Left Hand Side Initial reading On Right hand side at 3.0m at 3.0m No of blows Reading penetration Station No of blows Reading Penetration Station No of Blows Reading Penetration mm mm 0+500 mm mm 0+500 mm mm 0 88 0 0 85 85 0 82 82 5 124 36 5 127 42 5 115 33 5 167 43 6 167 125 5 164 131 5 214 47 5 188 63 5 220 89 5 247 33 5 214 151 5 245 156 5 281 34 5 243 92 5 330 174 4 297 16 5 274 182 3 374 200 1 414 117 10 350 168 3 415 215 1 432 18 5 382 214 3 457 242 1 451 19 5 414 200 3 500 258 1 474 23 5 448 248 2 526 268 1 495 21 5 484 236 2 554 286 1 520 25 7 533 297 2 580 294 1 545 25 5 566 269 3 617 323 1 588 43 5 600 331 3 644 321 1 652 64 3 622 291 3 667 346 1 667 15 3 652 361 2 683 337 1 680 13 2 671 310 2 699 362 1 694 14 1 711 17 1 679 369 1 705 343 1 727 16 1 687 318 1 712 369 1 743 16 2 700 382 1 720 351

None unpaved Date: 13/03/2010 On Right hand side

No of BlowsReading penetration mm mm 0 89 0 5 5 5 5 3 2 2 2 3 3 3 3 3 3 3 3 4 4 4

5 5

120 157 212 264 303 338 366 385 410 435 460 486 513 542 573 600 640 680 693 710 723

31 37 55 52 39 35 28 19 25 25 25 26 27 29 31 27 40 40 13 17 13

Dynamic Cone Penetrometer (D.C.P) test Chainage Cone angle

0+1200 60

Layers removed

None

Surface type

Unpaved

APPINDEX D-8

Zero error DCP Field results On Left Hand Side at 3.0m No of blows 0 5 5 5 5 5 5 5 3 3 3 3 3 4 3 5 2 2 2 1

Reading mm 80 117 140 172 215 265 317 369 394 420 444 475 502 540 580 654 678 698 719 723

penetration mm 0 37 23 32 43 50 52 52 25 26 24 31 27 38 40 74 24 20 21 4

Initial reading Station 0+1200

Date 13/03/2010 On Right hand side No of Blows Reading mm 0 75 5 119 5 170 5 221 5 281 5 350 5 415 5 489 3 542 3 589 3 635 3 683 2 713 1 732 1 746 1 764 1 783 1 805

Penetration mm 0 44 51 51 60 69 65 74 53 47 46 48 30 19 14 18 19 22


92


93

Appendix D-9: DCP charts

CH 0+00 L CH 0+00 R

CH 0+500 L

CH 1+100

CH 0+500 R

CH 1+100


93


94

Appendix D-10: Particle size determination PARTICLE SIZE DETERMINATION Up Grading Nsambya-Kirombe road to Bitumen standards

Project: Location: Soil Description:

Soil Description: sandy SILT of intermediate plasticity (MIS) 1

Source

Sampling Date: 20/03/2010 Testing Date:

23/03/2010

Dry weight, M3 :

900

B.S. sieve (mm)

Aperture size (mm)

Partial weight retained (g)

Percentage retained (%)

Percentage Passing (%)

75.00

75.00

0

0.0

100

50.00

50.00

0

0.0

100

37.50

37.50

0

0.0

100

20.00

20.00

0

0.0

100

10

10

0

0.0

93

6.3

6.3

0

0.0

90

5.00

5.00

0

0.0

90

2.00

PARTICLE SIZE DISTRIBUTION 2.00 0 CHART

0.0

80

1.18

4.5

0.5

80

Percentage Passing (%)

99 97 1.18 95 93 91 0.60 89 87 0.425 85 83 81 0.300 79 77 0.212 75 73 71 0.150 69 67 65 0.075 63 61 Percentage 59 57 55 53 51 49 47 45 43 41 39 37 35

0.01

0.60

12.4

1.4

78

0.425

36.6

4.1

74

0.300

347.8

38.6

Specified limits (%ge passing) Lower limit

Upper limit

35 Grading curve

0.212

40.2

4.5

31 Lower limit

0.150

60.8

0.075

62.7

Finer than 0.075 mm Sieve

0.10

6.8

1.00 Sieve Size (mm)

7.0

24 Upper limit

17

17.2

10.00


94

Appendix D-11: Detrmination of Average least dimension

95

Appendix D-11: Detrmination of Average least dimension

Second Layer ALD=7mm

First Layer ALD=9.8m

Source,TRL,1993


95

Appendix E: Drainage Design

96

Appendix E: Drainage Design Appendix E-1, Drainage C, Coefficients MAP (mm) Factor

Component <300 300- 600 3.5% flat 0.01 0.02 Average slope of hillsides 3.5%-11% soft to 0.04 0.06 incatchment moderate 11%-35% steep 0.09 0.12 very permeable 0.02 0.03 permeable 0.04 0.06 Permeability of soil Semi-permeable 0.08 0.12 impermeable 0.15 0.21 Dense forest or very 0.02 0.03 loose deposits Cultivated Land or 0.04 0.07 Vegetation thin forest Grassland 0.13 0.17 Bare rock 0.24 0.26

Cs

Ck

Cv

>600 0.03 0.08 0.16 0.04 0.08 0.16 0.26 0.04 0.11 0.21 0.28

Appendix E-2, Intensity-Duration Curves Intensity -Duration Frequency curves 250

200

123mm/hr

Intensity in mm/hr

110mm/hr 150 2yr RP 5yr RP 10yr RP 25yr RP

100

50yr RP 100yr RP

50

0 0

50

100

150

200

250

300

350

Time in Minutes

9.9 mins


96


97

Appendix E-3, HW, Headloss determination

HW/D

1.38

Head loss

Source, Uganda Road Drainage Manual, 2005


97


98

Appendix E-4, Critical dept h determination

0.42


98


99

Appendix E-5, Rainfall data for Kampala Table 1

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29

Daily rainfall for Kampala for 29 years; Station Sewage Plant

Year 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 Sum X ( average)

Yearly daily max, mm/d max, mm/d 54.4 55.2 64.3 86 58.3 47.5 52.1 54.5 52.2 52.5 51.9 42.9 51.6 37.5 47 47 55.5 64.4 59.7 48.5 68 50.8 78.3 69.3 61.6 86.5 61 125.4 63 1746.9

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29

Descending order mm/d, 125.4 86.5 86 78.3 69.3 68 64.4 64.3 63 61.6 61 59.7 58.3 55.5 55.2 54.5 54.4 52.5 52.2 52.1 51.9 51.6 50.8 48.5 47.5 47 47 42.9 37.5 1746.9

Frequency of Return exceedance, f period, T, yrs Xi-X 65.162069 26.262069 25.762069 18.062069 9.062069 7.762069 4.162069 4.062069 2.762069 1.362069 0.762069 -0.537931 -1.937931 -4.737931 -5.037931 -5.737931 -5.837931 -7.737931 -8.037931 -8.137931 -8.337931 -8.637931 -9.437931 -11.73793 -12.73793 -13.23793 -13.23793 -17.33793 -22.73793

(Xi-x)^2 mm/hr 4246.095232 20.9 689.6962663 14.4 663.6841974 14.3 326.2383353 13.1 82.12109394 11.6 60.24971463 11.3 17.32281807 10.7 16.50040428 10.7 7.62902497 10.5 1.855231867 10.3 0.580749108 10.2 0.289369798 10.0 3.755576694 9.7 22.44799049 9.3 25.38074911 9.2 32.92385256 9.1 34.08143876 9.1 59.87557669 8.8 64.60833532 8.7 66.22592152 8.7 69.52109394 8.7 74.61385256 8.6 89.07454221 8.5 137.779025 8.1 162.254887 7.9 175.2428181 7.8 175.2428181 7.8 300.6038526 7.2 517.0135077 6.3 8122.908276

0.03 0.07 0.10 0.13 0.17 0.20 0.23 0.27 0.30 0.33 0.37 0.40 0.43 0.47 0.50 0.53 0.57 0.60 0.63 0.67 0.70 0.73 0.77 0.80 0.83 0.87 0.90 0.93 0.97

30.0 15.0 10.0 7.5 6.0 5.0 4.3 3.8 3.3 3.0 2.7 2.5 2.3 2.1 2.0 1.9 1.8 1.7 1.6 1.5 1.4 1.4 1.3 1.3 1.2 1.2 1.1 1.1 1.0

60.238

S(standard deviation)

17.032


99

Appendix F:Financial Documentation

100

Up Grading Nsambya-Kirombe road BILLS OF QUANTITIES FOR Nsambya-Kirombe Road Unit Quantity Rate (Ushs) BILL NO1: PRELIMINARIES

2.1

BILL NO.2: SITE CLEARANCE Clear all shoulders, carriage way and side drains of grass and all unwanted materials as instructed by the Engineer.

2

m

12,485

1000

Amount (Ushs)

12,485,000 -

2.2

Load and cart to spoil all debris and excess material which cannot be spread within the road reserve, spread all excess material as directed by the Engineer.

3

m

2,497

10,000

24,970,000 -

2.3

Fell down trees of a minimum diameter of 300 mm within the road reserve, load and cart away as directed by the Engineer

No.

Remove tree stumps, fill the hole appropriately as directed by the Engineer

No.

50,000

-

2.4

3.1

3

100,000

SUB TOTAL 2 BILL NO.3: DRAINAGE Clear existing fully blocked culverts,remove all debris, soils and stones. Cart away as directed by the Engineer (half rate for half blocked culverts)

300,000 37,755,000

3.1.1

Dia 450mm

m

20,000

-

3.1.2

Dia 600mm

m

25,000

3.1.3 3.2

Dia over 900mm Clean lined and unlined side drains, remove silt and unsuitable material and cart away as directed by the Engineer.

m

28,000

m

420

-

3.3

Clear and reshape mitre drains,

m

982

-

3.4

Excavate for side drains, catchwater drains, culvert outfalls and dispose of excavated material as directed by the Engineer.

m

3,000

-

3.6

Excavate in soft material for pipe culverts, headwalls, wingwalls, aprons, toe walls and drop inlet chambers to any depth as directed by the Engineer.

3

10,200

m

-

3.7

E.O. Item 3.6 for excavation in hard material

3.8

Provide concrete pipes . Use for bedding and backfilling approved material.

3

24,715

m

-

3.8.1

Dia 450mm

m

3.8.2

Dia 600mm

m

3.8.3

Dia 900mm

m

200,000 100

250,000 410,000

25,000,000 -


100

101

3.8.4

Dia 1200mm

3.11

Construct culvert end structures (Headwalls wingwalls,toe walls, splash aprons in concrete of Minimum height of 0.3 m above road level) Using stone masonary and cement sand mortal 1:3,

3.11.1

3.12 3.12.1 3.13

m

640,000

-

m2

Line drains using Stones masonary

m2

Demolition and removal of existing culverts, spoil materials as directed by the Engineer.

m

42

2,247

3

130,000

40,000

30,000

5,460,000 89,892,000 -

3.14

3.14.2 3.15 3.15.3 3.16

4.2

4.2.1

Provide and lay pedestrian and cover slabs made out of reinforced concrete of dimensions 1.0x 0.5 x 0.15

No

45,000

No.

31,000

m

263,000

Provide scour checks made out of Stones with planted grass Construct sub surface French drains

120,352,000

SUB TOTAL 3 BILL NO.4: WEARING COURSE AND SHOULDERS. Existing Paved carriageway and paved Shoulders Scarify and compact of existing pavement and/or shoulders to at least 95% MDD MOD AASHTO density.

-

m2

12,485

1000

12,485,000 -

4.2.2

Scarify and cart to spoil unwanted material.

4.2.3

Add approved granular materials, spread, water and compact in layers to 150 mm thickness to at least 95% MDD MOD AASHTO on the carriageway as directed by the Engineer. Free haulage up to 10 Km.

3

m

1,047

10,000

10,470,000 -

m3

4,086

25,000

102,150,000

4.2.4

Provide, lay shape and compact crushed stone base in layers not exceeding 150 mm thickness to at least 97% MDD Mod. AASHTO density

m3

140,000

3

20,000

-

4.2.5

Trim and clean potholes and edges and fill with approved granular material.

4.2.6

Provide and transport stabilising agent to natural base material Lime Cement

m

-

4.2.6.1 4.2.6.2

Ton Ton

98.3

600,000 800,000

59,001,840 -

4.2.7

Provide, transport and mix quarry dust at a rate varying from 10 to 30 percent by volume with natural base material while carrying out mechanical stabilisation

m3

52,500

-


101

102

4.2.8

E.O. Items 4.2.6 for processing and mixing stabilising agent material at a rate varying from 3 to 5 percent by weight as directed by the Engineer.

3

m

2,043

10,000

20,430,000 -

4.2.8

Prepare base course surface, provide, heat and spray MC 30 cutback bitumen prime coat at 2 the rate of 0.7-1.0L/m or as directed by the Engineer.

2

m

9,489

4,500

42,698,700 -

4.2.10 4.2.11

Seal potholes and edges with a Premix layer of a 50 mm thickness. Provide, heat and spray first seal coat of 80/100 penetration bitumen at the rate of 1.22 1.5L/m .

2

310,000

m

2

m

9,489

6,000

56,931,600 -

4.2.12

Provide, spread and roll 14/20mm nominal 2 3 sized chippings at the rate of 95m /m

4.2.13

Provide, heat and spray second seal coat of 80/100 penetration bitumen at the rate of 1.02 1.2L/m

m2

9,489

6,000

56,931,600 -

2

m

9,489

6,000

56,931,600 -

4.2.14

Provide, spread and roll 10/14mm nominal 2 3 sized chippings at the rate of 130m /m

4.2.15

Provide, heat, and spray 80/100 tack coat at a rate of 0.3-0.6L/m2 on existing tarmac surface.

2

m

9,489

6,000

56,931,600 -

4.2.16 4.3 4.3.1

Provide, heat, mix, lay and compact asphalt concrete wearing course of 50mm thickness

2

m

6,000

2

68,000

m2

450

m

Unpaved carriageway and shoulders Shape road surface by heavy grading to camber or cross fall including side drains, all inlets and outlets of the drainage with a grader and compact to 95% MDD Mod. AASHTO.

-

-

4.3.2

Shape road surface by medium grading to camber and cross fall including side drains, all inlets and outlets of the drainage with a grader and compact to 95% MDD Mod. AASHTO.

2

m

450

-

4.3.3

Provide and transport up to 10km, spread water and compact in layers not exceeding 150 mm thickness to at least 95% MDD MOD.AASHTO. Approved Natural base material

3

m

22,000

-

4.3.4

Add lime stalised base at the rate of 3-5% by weight as directed by the Engineer

3

m

4500

-


102

103 4.4 4.4.1

4.4.2

4.4.3

4.4.4

-

EARTH WORKS Provide and transport up to 10km, spread water and compact in layers not exceeding 150 mm thickness to at least 95% MOD.AASHTO. fill material to a thickness instructed by the Engineer Compact existing gravel material, water and compact in layers not exceeding 150mm thickness to atleast 95% MDD Mod ASSHTO, Fill in soft material(sub grade) ,water and compact in layers not exceeding 300mm thickness to atleast 95% MDD Mod ASSHTO Fill in hard material,water and compact in layers not exceedind 150mm thickness to atleast 95% MDD Mod ASSHTO

m3

-

m3

m3

1,000

m3

22,000

-

970

-

22,000

20,000

SUB TOTAL 4

22,000,000

-

496,961,940

BILL NO. 5: Ancillary Works 5.1

Remove, transport and store existing road sign. Make necessary repairs, repaint and reerect.

No.

20,000

5.2

Povide and erect standard regulator typesigns of size 600mm.

No.

180,000

5.3

Provide anderect standard warning type signs of size 900mm.

No.

5.4

Provide and erect standard informatory signs of size 500x600m

No.

900,000

5.5

Provide and erect non-standard information signs of area under 1m2

No.

950,000

5.6

As item 5.5 but area between 1 and 2m2

No.

5.7

Prepare road surface, spray white road marking lines 100mm wide.

m

10,000

5.8

As item 5.8 but yellow

m

10,000

5.9

Provide, prepair and paint kerb stones

m

15,000

5.1

Provide and install RC Km marker posts

No.

30,000

5.11

Provide and lay precast concrete half batter kerbstones to sides of road

m

15,000

5.12

Excavations for foundation gabions

m3

30,000

5.13

Deliver, place and fill gabion boxes with approved stones.

m3

75,000

SUB TOTAL 5

2

1

900,000

1,000,000

1,800,000

1,000,000

-

2,800,000


103

104 5.13

Deliver, place and fill gabion boxes with approved stones.

3

m

75,000

SUB TOTAL 5 BILL NO. 6: DAY WORKS 6.1

2,800,000

Equipment

6.1.1

D6 Bulldozer complete a blade and ripper

hr

85,000

6.1.2

D8 Bulldozer complete a blade and ripper

hr

105,000

6.1.3

Traxcavator 165HP with loader attachments bucket size 1-2m3

hr

75,000

6.1.4

Wheel loader 105HP and 1.8m3 bucket capacity

hr

75,000

6.1.5

Motor grader 135HP complete with the blade, ripper and scarifier

hr

70,000

6.1.6

7 ton tipper

hr

40,000

6.1.7

10 Ton tipper

hr

50,000

6.1.8

15 Ton tipper

hr

60,000

6.1.9

Pedestrian Roller

hr

10,000

6.1.10

7 Ton Vibrating roller

hr

30,000

6.1.11

Pneumatic tyred roller

hr

41,000

6.1.12

Water pump

hr

4,000

6.1.13

Water bowser ,6000 litre

hr

37,500

6.1.14

Bitumen Sprayer

hr

41,000

6.1.15

Bitumen boiler

hr

41,000

6.1.16

Asphalt plant

hr

57,000

6.1.17

Chips spreader

hr

30,000

6.1.18

Mechanical Broom

hr

25,000

6.1.19

Pick up

hr

10,000

6.1.20

Concrete mixer

hr

30,000

6.1.21

Concrete vibrator (poker type)

hr

10,000

6.1.22

Compressor (minimum 120 litre pwe min) Complete with all tools, tools, hoses, steels etc.

hr

61,000


104

105 6.2

MATERIALS

6.2.1

Ordinary Portland cement

Ton

680,000

6.2.2

Road lime

Ton

600,000

6.2.3

Quarry dust

m

6.2.4

Course aggregate of size betwwen 6mm25mm

m

6.2.6

Wrought shattering timber

6.2.7 6.2.8

3

62,400

3

65,000

m

3

18,000

Instant road repair materials (Cold premix)

Kg

2,400

Gentex High Density Polyethylene (HDPE) pipe culverts of diameter; 600 mm (31 mm thickness) 900 mm (50 mm thickness) 1,000 mm (56 mm thickness) 1,200 mm (62 mm thickness) 1,500 mm (80 mm thickness)

m m m m m

360,000 510,000 600,000 680,000 720,000

Hard core

m

3

37,500

Reinforcement steel Mild High tensile LABOUR

Kg Kg

5,000 5,000

6.3.1

Unskilled labour

hr

8,000

6.3.2

Semi-skilled labour

hr

12,000

6.3.3

Skilled labour

hr

20,000

6.2.8.1 6.2.8.2 6.2.8.3 6.2.8.4 6.2.8.5 6.2.9 6.2.10 6.2.10.1 6.2.10.2 6.3

SUB TOTAL 6 SUMMARY 37,755,000 120,352,000 496,961,940 2,800,000

SUB TOTAL BILL NO 2 SUB TOTAL BILL NO 3 SUB TOTAL BILL NO 4 SUB TOTAL BILL NO 5 SUB TOTAL BILL NO 6 TOTAL Mobilisation Supervision Quality control Total GRAND TOTAL

657,868,940 5% 4% 2%

32,893,447 26,314,758 13,157,379 72,365,583 730,234,523

Adopted from MBJ Technologies, 2010


105

Appendix G: Appraisals

106


Environmental impact assessment Report. Environmental impact assessment(EIA) is a systematic and inter-displinary evaluation of the potential positive and negative environmental effects of a proposed project/program.EIA identifies ,predicts and evaluates the foreseeable environmental iimpacts,both beneficial and adverse(JICA,2009) of a project with a view to eliminating where possible, or minimizing the negative impacts while optimising the positive impacts. Introduction The objective of the EIA study is to assess the positive and negative environmental effects (Biophysical/socio-economic and cultural) of the intended road construction project when upgraded to bitumen standard, and to propose measures for mitigating negative impacts and enhancing positive ones. The following are specific requirements for the study: Review and update the feasibility study prepared by the original design consultancy; and • Review and update the detailed design and tender documents, which includes an Environmental Impact Assessment as well as a Social Impact Assessment (SIA) in accordance with the Ugandan environmental laws. The study addresses the existing alignment and a number of proposed options in terms of certain strategic alternative alignments for particular sectors. Purpose of the report Following the enactment of the National Environmental Statute (1995), the National Environment Management Authority was created and charged with the responsibility to oversee, coordinate and supervise the activities of the Environmental Impact Assessment (EIA) process in Uganda. Environmental Impact assessment is concerned with identifying, predicting and evaluating the foreseeable environmental impacts, both beneficial and adverse, of public and private development policies, programs and projects, with a view to minimize the negative impacts while enhancing the positive ©Final Year Individual project, Upgrading Nsambya-Kirombe road to a bituminous paved surface. Kyambogo University, Kampala Uganda 2009/10

106


107

impacts. Environmental Impact Assessment is a tool for better planning. It permits the integration of environmental concerns into the policy, program and project planning process at the earliest possible stages. Depending on the significance of the environmental impacts of the proposed project, the law exempts small projects which do not have a potential significance or whose impacts can easily be identified and for which mitigation measures can readily be prescribed and be included in the design and implementation of the project without need for an EIA study requiring field investigations. However projects whose development poses potential significant impacts are subject to an EIA process. This report has been prepared as part of the requirement in Environmental Impact Assessment carried out along Nsambya-Kirombe road in May 2010

to incorporate an Environmental Impact

Assessment indicating the likely impacts of upgrading Nsambya-Kirombe road to a bituminous paved and giving their mitigation measures. Methodology The study involved the use of available literature, public participation, and direct observation. The available literature on the flow process of an EIA, regulatory framework and EIA requirements for road construction works were consulted to come up with a comprehensive report on the proposed development Consultation with the public As a legal requirement according to National Environment Statute, 1995 and as a need to involve the views of the stakeholders within the development process of the project, the public was interviewed on the likely impacts of upgrading the road. It involved consulting the residents along the proposed road, environmental officers in the two areas of Nsambya and Kirombe, Kampala city planning authority, Ministry of lands, ministry works and transport officials. Direct observation A site visit was made where some of the environmental issues were directly observed including the site surroundings. Regulatory / Legal Frame Work The Ugandan constitution provides for protection and conservation of environment. Principal XXXII under state policy provides for promotion of sustainable development and public awareness in management of land, air and water resources. The state is ©Final Year Individual project, Upgrading Nsambya-Kirombe road to a bituminous paved surface. Kyambogo University, Kampala Uganda 2009/10

107

The investment code No. 18 of 1987

108

required to take all possible measures to prevent or minimize damage and destruction of land, air and water resources due to pollution or other causes. Article 39 of the constitution, provides for individual right to a clean and health environment. This provision is complemented by article 50, which gives any person the right to seek judicial action to redress the breach of a fundamental right, irrespective of whether the breach affects him or another person. The land act: The land act regulates the ownership of land and controls land use. Section 44 obliges any person who owns or occupies land to manage and utilize it in accordance with the existing laws including the national Environment statute, forest act and any other law. Section 46 of the act requires that any use of land should conform to Town and Country planning Act and other laws. An EIA is therefore a useful tool to quarantine that the proposed land use does not contravene any law. The investment code No. 18 of 1987 This code empowers the Uganda Investment Authority to, among other things, attract and coordinate all local and foreign investments in the country to enhance economic development. Section 19 of the code requires every investment license to take necessary steps to ensure that the operation of its business enterprise does not cause any injury to the ecology or the environment hence a need for an EIA. The Environmental Impact Assessment Regulations, 1998 The EIA Regulations elaborate in detail the provisions of the National Environmental Act and present the details of the EIA process and roles of various stakeholders. The Regulations make it an Offence for any person to commence, proceed or execute any project with significant impact on the environment without approval from NEMA. The regulations also advocate for principle of full disclosure in the conduct of EIAs and make it an offence to make false statements in an EIA. The regulations in particular lay down the requisite steps to be adopted by a developer in carrying out an environmental assessment. The National Environmental Act cap.153, 1995 The National Environment Act is a coordinating Act and includes EIA in its general principals as a requirement for the proposed projects and activities, which may significantly affect the Environment or use of natural resources. It establishes the National Environment Management Authority (NEMA) as a coordinating, monitoring ©Final Year Individual project, Upgrading Nsambya-Kirombe road to a bituminous paved surface. Kyambogo University, Kampala Uganda 2009/10

108

Impacts of the project on the environment

109

and supervisory body. Its provisions are to be carried out through cooperation between NEMA and other government agencies through a system of consultation. The Employment Act, 2006 The act applies health and safety requirements to every workplace or working environment” (section 2, Act 9/2006), it applies to both private and public employers. It imposes duties on employers, manufactures, suppliers and transporters to exercise due care and ensure safety at workplaces, and for articles, chemicals which are manufactured, supplied or transported. General health and welfare provisions are made including sound construction, space, ventilation, cleanliness, lighting, water, sanitary conveniences and first aid facilitates ( part viii) but there are also specific provisions regarding fire preparedness (part x), the safety of machinery, plant and equipment (part xi). Impacts of the project on the environment The road proposed to be upgraded joins two commercial centres, has residents along it and natural physical features like trees along it. There are a number of existing physical structures in the project area and development of the proposed project shall have impacts on these existing structures. The notable impacts include; •

Noise resulting from vehicles, graders, vibrators and the road workers

themselves. •

Vibrations resulting from the heavy vehicles and the excavators while upgrading

the road •

Air pollution as a result of the fumes from the exhausts and dust raised into space

by wind. •

Waste material resulting from the cut soil, and vegetation

•

Air pollution as the trees and shrubs shall be cut during the clearance of the road

reserve land •

Water pollution while constructing across the water stream.

•

Blockage of the drainage channels along the road by the cut soil. This shall lead

to increased soil erosion. •

Accidents on site as result of poor health and safety equipment and recklessness

on the roads. ©Final Year Individual project, Upgrading Nsambya-Kirombe road to a bituminous paved surface. Kyambogo University, Kampala Uganda 2009/10

109

Impact mitigation measures •

Displacement of people owning land along the proposed development

•

Disturbance of the ecosystem. The cut trees act as habitats for birds and other

110

living organisms like insects and therefore removal of such vegetation shall imply migration of the species from the land. However the upgrading of Nsambya-Kirombe road shall bring positive impacts on the people living along the road and those staying in the two trading centres. Namely; •

Employment opportunities to the people especially during the construction phase

•

Improved service delivery such information, trade goods, funds, hotels, schools

and hospitals to the people •

Reduced dust after the road has been tarmac

•

Improved insecurity as the road shall be clear of the bushes and ditches which act

as hiding places for thugs and thieves. Impact mitigation measures •

Use of special road surfacing like porous asphalt to reduce tyre noise,

construction of noise barriers, restriction on heavy vehicles, smoothing of traffic flow and minimizing stops, and shielding of noise-sensitive buildings •

Speed and weight restrictions on heavy vehicles, isolation of buildings by

resilient amounts, and Installation of better fitting windows for reducing airborne vibration •

Use of more efficient lean burn engines and design of carburettors, better engine

maintenance, and planting of trees and shrubs along the road. •

Disposal of the cut soil and vegetation to a landfill. Provision of convenient

litter receptacles to reduce waste levels on the roads. •

Adequate road maintenance and design, heavy vehicle restriction and proper law

enforcement reduce road accidents. •

Relocation and compensation of the displaced people

•

Planting of trees along the road may maintain the ecosystem of the land by

providing habitat for the birds and insects. The road proposed to be upgraded joins two commercial centres, has residents along it and natural physical features like trees along it. Upgrading the Nsambya-Kirombe road ©Final Year Individual project, Upgrading Nsambya-Kirombe road to a bituminous paved surface. Kyambogo University, Kampala Uganda 2009/10

110

Impact mitigation measures

111

would bring a number of significant impacts. However the application of the suggested mitigation measures shall eliminate or minimize the identified impacts. Approval of this proposed project shall generate more benefits to the surroundings including employment opportunities as already cited. Implementation of such mitigation measures shall require establishment of a monitoring team by the developer.


111

Impact mitigation measures

112

Appendix H: Photographs

Figure 1.2: Google Earth image of project road

Figure 1. 3: Testing subgrade soils


112

113

Appendix I: Project Drawings


113

Proposed work schedule

1

Final Year Individual project, Upgrading Nsambya-Kirombe road to a bituminous paved surface. Kyambogo University, Kampala Uganda 2009/10

1

Proposed Spending plan

1

ITEM

Final year project spending plan

Feasibility studies

Projected

site visits sensitization

Total Feasibility studies

Actual

Resources

50000

1000000

100000

-900000 Community Leaders,Project Manager

1100000

150000

-950000

Projected

Geomertry

Difference

100000

Actual

-50000 Project Manager

Difference 0

Traffic counts 20000

20000

Fuel

400000

50000

pens Policemem

5000

5000

100000

60000

Clip boards

Enumerators

0 Enumerators 350000 Project Manager 0 Resource persons 40000 Supervisor

1400000

300000

1100000

Transport

200000

100000

100000

Surveying

1000000

200000

800000

1925000

435000

1490000

Total Geomertry Pavement design

Projected

Actual

Difference

CBR(DCP)

200000

150000

Atterberg limits

300000

100000

200000 Technician

compaction

200000

100000

100000 Supervisor

sieve analysis

100000

50000

50000

800000

250000

550000

Total Pavement design Drainage design Rainfall data

Projected

Actual 1500000

Difference

200000

Topo map

500000

Draftsman

500000

20000

2500000

220000

Total Drainage design Environmental, asssessments

Projected

Consultations

50000 Project Manager

1300000 Project Manager 500000 Resource persons

Actual

480000 Supervisor 2280000 Difference

100000

100000 Project Manager 0 Resource persons

100000

Environmental, asssessments Miscelleneous Air time

Projected

0 Actual

100000 Difference

100000

50000

50000

50000

0

1000000

300000

700000

Printer

200000

100000

100000

Draftsman

300000

50000

250000

5625000

1355000

4270000

Refreshments Computer

50000 Project Manager


1

Final Year Project Report.

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