Lecturer: Dr. Basil David Daniel
B F C 3 2 3 0 2 T r a ffff i c E n g i n e e r i n g a n d S a f e t y
Chapter 1
Traffic volume is ......
Traffic Flow
the number of vehicles passing a given point during a specified period of time What you will be learning from this chapter …
TRAFFIC STUDIES Traffic Volume
Lecturer: Dr. Basil David Daniel
B F C 3 2 3 0 2 T r a ffff i c E n g i n e e r i n g a n d S a f e t y
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Spot Speed
The importance of traffic volume study ...... For traffic planning, design & research. To determine the efficiency of a traffic system.
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TRAFFIC FLOW THEORY
To evaluate the quality of service of a transport facility.
Traffic Flow Parameters
To design roads – number of lanes & pavement thickness.
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Speed, Flow & Density Relationship
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Volume study methods ...... Manual Count Methods
CAPACITY & LEVEL OF SERVICE
Automatic Count Methods
Multilane Highway Capacity Study
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Lecturer: Dr. Basil David Daniel
B F C 3 2 3 0 2 T r a ffff i c E n g i n e e r i n g a n d S a f e t y
Manual Count may be used for determining ......
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Lecturer: Dr. Basil David Daniel
B F C 3 2 3 0 2 T r a ffff i c E n g i n e e r i n g a n d S a f e t y
Manual Count method ......
Vehicle classification
Applied when small sample of data is required.
Turning movements
For periods less than one (1) day.
Direction of travel
Normal intervals are 5, 10 or 15 minutes.
Pedestrian movements
Counts are not usually taken on Mondays, Fridays and weekends.
Vehicle occupancy
Can anyone explain why ?
Automatic Count may be used for determining ...... Vehicle hourly patterns Manual Count recording methods ...... Tally Sheets
Daily or seasonal variations and growth trends Annual traffic estimates
Mechanical Counting Boards Count periods ......
Electronic Counting Boards
2 hours (peak period), 4 hrs (morning & evening peaks), 6 hrs (morning, afternoon & evening peaks), 12 hrs (daytime)
B F C 3 2 3 0 2 T r a ffff i c E n g i n e e r i n g a n d S a f e t y
Tally sheet
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Lecturer: Dr. Basil David Daniel
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B F C 3 2 3 0 2 T r a ffff i c E n g i n e e r i n g a n d S a f e t y
Lecturer: Dr. Basil David Daniel
Manual counting board Automatic Count method ...... Applied when large sample of data is required. For periods more than one (1) day. Normal intervals are 1 hour for a 24 hour period. Counts may extend to a week, month or year. Automatic Count recording methods ...... Portable Counters Permanent Counters Videotape
Electronic counting board 5
BDD/BFC32302/1A
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Lecturer: Dr. Basil David Daniel
B F C 3 2 3 0 2 T r a ff i c E n g i n e e r i n g a n d S a f e t y
B F C 3 2 3 0 2 T r a ff i c E n g i n e e r i n g a n d S a f e t y
Lecturer: Dr. Basil David Daniel
INTERSECTION COUNT
PORTABLE COUNTERS
Intersection counts are required for timing traffic signals
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designing channelization
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planning turn p rohibitions
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Automatic Traffic Recorder
computing capacity
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Vehicle Classifier System
analyzing high crash intersections
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evaluating congestion
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PERMANENT COUNTERS
Uses manual count method. For simple intersections, a single observer may be sufficient. For complex intersections, several observers may be required.
Loop Detector 7
B F C 3 2 3 0 2 T r a ff i c E n g i n e e r i n g a n d S a f e t y
Lecturer: Dr. Basil David Daniel
PEDESTRIAN COUNT
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B F C 3 2 3 0 2 T r a ff i c E n g i n e e r i n g a n d S a f e t y
Lecturer: Dr. Basil David Daniel
VEHICLE CLASSIFICATION COUNT
Pedestrian counts are required for
Vehicle classification counts are used to
evaluating sidewalk and crosswalk needs
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justifying pedestrian signals
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establish structural & geometric design criteria
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timing traffic signals
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Counts are conducted at intersection crossings, midblock crossings or along sidewalks.
Classification counts should be conducted
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compute estimated highway user revenue
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compute capacity if the percentage of heavy trucks is high
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When pedestrians are tallied, those 12 years and above are classified as adults.
if vehicle mix at a crash site is a contributing factor to the crash problem •
Cars, MPVs, SUVs, 4WDs may be c lassified as passenger cars.
Intersection crossing
Heavy vehicles such as trucks and buses may be classified as trucks. Midblock crossing 9
B F C 3 2 3 0 2 T r a ff i c E n g i n e e r i n g a n d S a f e t y
Lecturer: Dr. Basil David Daniel
ADT and AADT COUNT
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B F C 3 2 3 0 2 T r a ff i c E n g i n e e r i n g a n d S a f e t y
Lecturer: Dr. Basil David Daniel
AADT volume count has the following uses:
ADT – Average Daily Traffic
Measuring or evaluating the present demand for service by the roadway or facility.
Represents 24-hr count.
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Developing the major or arterial roadway system. AADT – Average Annual Daily Traffic
Locating areas where new facilities or improvements to the existing facilities are needed.
Represents the 24-hr traffic volume averaged over a full 365-day year.
Programming capital improvements.
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Requires the use of an automatic counter. Accuracy depends on existing roadway, weather and traffic demand conditions.
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BDD/BFC32302/1A
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Lecturer: Dr. Basil David Daniel
B F C 3 2 3 0 2 T r a ff i c E n g i n e e r i n g a n d S a f e t y
Spot speed study ......
Lecturer: Dr. Basil David Daniel
B F C 3 2 3 0 2 T r a ff i c E n g i n e e r i n g a n d S a f e t y
When carrying out a spot speed study, make sure t he observer and the measuring instrument does not influence drivers’ speed. The measuring instrument must be concealed from the approaching drivers.
A study of speed of traffic at one point or spot on a trafficway. Consists of a series or sample of observations of individual speeds of vehicles approaching an intersection or passing a point at a nonintersection.
Recording of data should be made a s inconspicuous as possible.
Used to estimate the speed distribution of an entire traffic stream at that location under prevailing traffic conditions. Spot speed studies are carried out at ......
Accumulation of on-lookers must be avoided. Recommended study periods: In three parts during off-peak periods:
Trend locations – straight, level, open sections of rural highways, and midblock at urban streets.
1 hour between 6 am – 12 pm, 1 hour between 3 pm – 6 pm, and 1 hour between 8 pm – 10 pm.
Problem locations – accident blackspots, and locations where traffic signals and signs are contemplated.
whereby observations must be done in an hour, or not less than 50 vehicles for each period.
Representative locations – for basic data surveys. Locations of before-and-after studies. 13
Lecturer: Dr. Basil David Daniel
B F C 3 2 3 0 2 T r a ff i c E n g i n e e r i n g a n d S a f e t y
The course length of a spot speed study depends on : average speed of the traffic stream
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Lecturer: Dr. Basil David Daniel
B F C 3 2 3 0 2 T r a ff i c E n g i n e e r i n g a n d S a f e t y
Recommended course lengths: Average speed (km/h)
Course length (m)
< 40
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40 – 65
54
> 65
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STOPWATCH METHOD
Recommended sample size: at least 50, preferably 100 Like volume studies, spot speed studies are also not taken on Mondays, Fridays and weekends. Spot Speed Study methods ...... Stopwatch Method Radar/Laser Meter Method Pneumatic Road Tube Method 15
B F C 3 2 3 0 2 T r a ff i c E n g i n e e r i n g a n d S a f e t y
Lecturer: Dr. Basil David Daniel
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Lecturer: Dr. Basil David Daniel
B F C 3 2 3 0 2 T r a ff i c E n g i n e e r i n g a n d S a f e t y
RADAR / LASER SPEED METER PNEUMATIC ROAD TUBE METHOD
METHOD
Recorder
Pneumatic Road Tubes
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BDD/BFC32302/1A
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Lecturer: Dr. Basil David Daniel
B F C 3 2 3 0 2 T r a ff i c E n g i n e e r i n g a n d S a f e t y
A spot speed study was conducted along a state road experiencing frequent road accidents. The posted speed limit of the road is 60 km/h. The spot spee d data collected are shown in the following table: Speed Class (km/h) 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110
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–
–
–
–
–
–
–
–
–
–
–
–
–
–
44 49 54 59 64 69 74 79 84 89 94 99 104 109 114
1 3 4 5 3 3 1 1
BDD/BFC32302/1A
Number of vehicles Vehicle Class 2 3 4 2 1 3 1 3 3 1 2 4 2 4 6 5 8 7 6 5 5 5 3 2 7 2 1 3 1 5 3 1 4 1 1 3
Total 5 8 12 10 15 21 16 11 10 4 5 4 5 1 3
NOTE Vehicle class 1: Motorcycles Vehicle class 2: Cars Vehicle class 3: Vans and medium trucks Vehicle class 4: Heavy trucks and buses
Analyse the spot speed data and present findings of this study.
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