Module 1: Work Zone Traffic Control
Overview of Module 1 • Unde Underly rlyin ing g princ principl iples es of work work zone zone traf traffic fic control • Manu Manual al of of Unifo Uniform rm Tra Traffi ffic c Contr Control ol Dev Device ice – Features of work zone traffic control control
• Haza Hazards rds asso associa ciate ted d with with work work zon zone e traff traffic ic control • Inju Injury ry pre preve vent ntio ion n tech techni niqu ques es • Summary
Work Zone Traffic Control • Influ Influen ence ces s driv driver ers’ s’ perce percept ptio ion n of risk risk – Provides information on potential hazards – Minimizes aggressive behavior – Assists in navi navi ation
• Engin Enginee eerin ring g con conce cern rns s for for work work zone zones s – Primary focus: Safe and efficient movement of vehicles through work zone – Relatively less emphasis on safety of construction workers
Type of Barrier • Rigid Ba Barriers – Provide separation separation between • Opposi Opposing ng traffi traffic c lanes lanes • Traffi Traffic c lanes lanes and and work work area area
– Cause damage damage to motorists if struck struck
Concrete barrier separating opposing traffic
Concrete barrier separating traffic lanes and work area
Type of Barrier • Flex Flexibl ible e barrie barriers rs (cha (chann nnel elizi izing ng devi device ces) s) – Provide nominal protection for workers – Flexible and deformable, do not cause damage if struck Concrete barriers to se arat aratee work work area area
Flexible barrier separating traffic lanes and work area
Channelizing devices for delineation
Sample Road Projects and Potential Hazards
Vehicles parked within work area Passing traffic in close proximity to the on-foot worker with minimal protection from flexible barrier Flashing arrow board is not operating
Components of Temporary Traffic Control Zones (Source: MUTCD 2003)
• Advanced Warning Area • Transition Area • Activity Area – Work space – Traffic space
Buffer space (longitudinal) Traffic Space allows traffic to pass through the activity
Buffer Space (Lateral) provides protection from traffic and workers
Work space is set aside for workers, e ui ment, and material storage
Activity Area: where work takes place
Buffer Space (longitudinal) provides protection for traffic and workers
– Buffer space
• Termination Area
Termination Area: lets traffic resume normal operations
Downstream Taper
Transition Area: moves traffic out of its normal path
Work Space
Shoulder Taper
Work zone
Advance Warning Area: tells traffic what to expect ahead
Worker Safety Considerations in Work Zone Traffic Control • Modifying traffic control strategies to influence drivers’ perception of risk – Leads to more careful and slower driving – Improves safety for the workers
• Examples: – Providing active warning devices • Illuminated arrow boards • Reliable advisory speed limit • Active message with flashers – Narrower lane widths – Longer and/or wider buffer zones – Rigid barriers to separate workers from travel lanes
‘Positive Guidance’ Approach • May be used to improve safety in work zones • Combines highway/traffic engineering features with what rational drivers expect • – Various age groups of drivers – Complexity of work zone information handling – Limited capability of humans for detecting, processing, and remembering information
MUTCD – Manual on Uniform Traffic Control Devices • Recognized as the national standard • Enforcement agencies often adopt it by re erence • Provides guidance, options and supporting materials – To assist professionals in making decisions regarding the use of traffic control on streets and highways
MUTCD- Part 6: Temporary Traffic Control • Primary function of temporary traffic control: – “To provide for reasonably safe and efficient movement of road users through or around temporary traffic control zones while reasonably protecting workers, responders to traffic incidents, and equipment”
Temporary Traffic Control • Work zones present constantly changing conditions – – Creates higher degree of vulnerability for workers
Temporary Traffic Control Devices • Temporary traffic control (TTC) devices include – – – –
Signs Signals Markings Other devices
• Used to regulate, warn, or guide road users
Types of TTC Applications • Each TTC zone is different • Many variables affect the needs of each zone: – – – –
Location of work Duration of work Highway type Geometrics • Vertical and horizontal alignment, intersections, interchanges, etc.
– Road user volumes • Road vehicle mix (buses, trucks, and cars) and road user speeds
Work Duration • Major factor in determining the number and types of devices used in TTC zones • As per the MUTCD, five categories of work duration are defined: – Long-term stationary is work that occupies a location more than 3 days – Intermediate-term stationary is work that occupies a location more than one daylight period up to 3 days, or nighttime work lasting more than 1 hour – Short-term stationary is daytime work that occupies a location for more than 1 hour within a single daylight period – Short duration is work that occupies a location up to 1 hour – Mobile is work that moves intermittently or continuously.
Long Term Stationary Work (more than 3 days)
• Typically utilize a full range of TTC procedures and devices – time of TTC – TTC elements may include: • Larger channelizing devices, temporary roadways, and temporary traffic barriers • Retroreflective and/or illuminated devices
Intermediate-Term Stationary Work (up to 3 days, or nighttime work lasting more than 1 hour)
• May not be practical to use the same procedures or devices for long-term stationary TTC zones – Such as altered pavement markings, temporary traffic barriers, and temporary roadways
• Increased time to place and remove these devices could significantly lengthen the project, thus increasing exposure time
Short-Term Stationary Work (more than 1 hour within a single daylight period)
• Most maintenance and utility operations are short-term stationary work – Include activities that might involve different treatments – Devices having greater mobility might be necessary • Signs mounted on trucks
– Appropriately colored or marked vehicles with rotating/strobe lights may be used in place of signs and channelizing devices • May be augmented with signs or arrow panels
Short Duration Work (up to 1 hour)
• Often takes longer to set up and remove the TTC zone than to perform the work – Workers face hazards in setting up and taking down the TTC zone – Dela s affectin road users are si nificantl increased when additional devices are installed and removed
• Simplified control procedures may be warranted for short-duration work – Reduction in the number of devices – Use of high-intensity rotating, flashing, oscillating, or strobe lights on work vehicles
Mobile Work • Often involve frequent short stops for activities – Such as litter cleanup, pothole patching, or utility operations, and are similar to short-duration operations • TTC zones may includes: – Warning signs, high-intensity rotating, flashing, oscillating, or strobe lights on a vehicle, flags, and/or channelizin devices – Flaggers – A shadow vehicle equipped with an arrow panel or a sign following the work vehicle – Appropriately colored and marked vehicles with signs, flags, high-intensity rotating, flashing, oscillating, or strobe lights, truck-mounted attenuators, and arrow panels or portable changeable message signs may follow a train of moving work vehicles
Worker Safety Considerations • Key elements that SHOULD be considered to improve worker safety: – – – – – –
Training Temporary traffic barriers Speed reduction measures Planning of activity area Planning for worker safety Worker safety apparel
Worker Safety Consideration TRAINING • All workers should be trained on: – Working safely adjacent to vehicular traffic – Work zone traffic control techniques – Device Usage • Safety devices • Traffic control devices
– Placement of traffic control devices
• Relevant OSHA Regulation – 29 CFR 1926.21, Safety Training and Education
Worker Safety ConsiderationWORKER SAFETY APPAREL • Workers near motor vehicle traffic should wear bright, visible clothing • Relevant OSHA Regulation – 29 CFR 1926.95, Criteria for Personal Protective E ui ment
Worker Safety Consideration TEMPORARY TRAFFIC BARRIERS • Barriers shall be placed along the work zone depending on: – Lateral clearance of workers from adjacent traffic – Speed of traffic – ura on an ype o opera ons – Time of day – Volume of traffic
• Relevant OSHA Regulations – 29 CFR 1926.200(g), Traffic Signs – 29 CFR 1926.201, Signaling – 29 CFR 1926.202, Barricades Concrete Barriers
Worker Safety Consideration – SPEED REDUCTION MEASURES • Speed of passing motorists may be influenced by: – – – – –
Regulatory speed zoning Funneling Use of law enforcement Lane reduction Presence of flaggers
Worker Safety Consideration – PLANNING THE ACTIVITY AREA • Plan internal work space and activities – Minimize the use of backing maneuvers of construction vehicles – equipment and trucks
,
• Minimize worker exposure to risk – Develop internal traffic control plan and operations • Refer to “Module 2: Safe Operations and Internal Traffic Control in the Work Space”
Worker Safety Consideration – PLANNING FOR WORKER SAFETY • Hazard assessment should be conducted based on: – Characteristics of work site –
• Must comply with all relevant OSHA regulations – Assess worker risk exposures for each job site and job classification • 29 CFR 1926.20, General Safety and Health Provisions • 29 CFR 1926.20 (b) (2)
Optional Worker Safety Elements • • • •
Shadow Vehicle with Impact Attenuator Road Closure Police enforcement Additional Lighting – – – – – –
Rumble strips Changeable message signs Hazard identification beacons Flags Warning lights Intrusion warning devices Rumble strips
Optional Worker Safety Elements SHADOW VEHICLE • Common for mobile and constantly moving operations • with: – Appropriate lights – Warning signs – Rear-mounted impact attenuator
Shadow vehicle with rear mounted crash attenuator
Truck Mounted Attenuator Crash with a truck with a truck mounted impact attenuator
Crash with a truck without an impact attenuator
Optional Worker Safety Elements ROAD CLOSURE • Reduce worker vulnerability to risk of injury • Provide more spacious activities • Eliminate threat of intruding vehicles from passing traffic • Aid in faster project completion
Freeway closure for one direction of traffic
Optional Worker Safety Elements USE OF POLICE ENFORCEMENT • Police units may be stationed in a work zone to: – passing motorists – Improve safety through work zone by enforcing speed limits
Optional Worker Safety Elements LIGHTING • Additional lighting should be provided at work zones that operate during the night • Nighttime work requires extra caution due to: – Poor night time visibility – Impairment of workers related to fatigue – Impairment of drivers
Nighttime work is common in highway/street construction projects
Sample Work Zone Traffic Control Layout • For a Single Lane Closure as per MUTCD – Pre-construction speed limit is 70 mph
REDUCED SPEED
Median
SPEED LIMIT
XX
AHEAD
REDUCED SPEED
SPEED LIMIT
XX
W21-4
W20-5
1400’
700’
R2-5b
Flashing Arrow Panel
XX
AHEAD
W4-2R
700’
KEY Channelizing Devices Sign Location
700’
R2-1
700’
700’
G20-2
600’
Note: Distance in feet, drawing not to scale
Work Zone Traffic Control • MUTCD provides minimum requirements • Various demanding situations may warrant enhanced safety precautions, such as: – Nighttime work – Inclement weather conditions – Unusual roadway geometry and environment – Combinations of the above
• Going beyond existing standards/guidelines may be necessary to ensure highest levels of traffic and worker safety
Work Zone Traffic Control Hazards and n ury reven on ec n ques
Hazards of Work Zone Traffic Control Common Hazards • Passing motorist intruding into the work space •
azar s re a e
o agg ng
• Nighttime hazards
Hazards of Work Zone Traffic Control Causal Factors • Conditions unexpected by the moving traffic – Violation of driver expectancy
• Conditions unexpected by the workers – Aggressive drivers – Unplanned work zone/activity
• Injuries can occur due to – Motorists’ mistakes – Workers’ mistakes – Deficiencies in the work zone environment
General Preventive Measures • Traffic Control
• On-foot workers
• Flaggers – Use portable radio – Use additional – Use a flashing communication warning devices slow/stop paddle equipment – Maintain signs properly –
se roper ane markings
• Law enforcement – Use officers and radar surveillance for traffic speed control
Hazard: Passing Motorists Intruding Into Work Space • Causes of Hazards – High approach speed – Improper geometry of the lane shift – mproper ra c con ro – Inadequate information system
• Hazard mitigation measures
No physical separation between work space and traffic lane
– Use of proper speed reduction methods – Proper design of the wok zone – Provide effective traffic control measures
Hazard: Passing Motorists Intruding Into Work Space Preventive Measures: • Exceed minimum standards/guidelines for traffic control – Rumble strips – Lane drop arrows – Lighted raised pavement markers – Radar triggered speed display – Safety warning system – Combinations of the above
Truck may intrude into the work zone
Sample Work Zone Traffic Control Layout With Additional Safety Features • For a Single Lane Closure Retroreflective Raised Pavement Markers Temporary Rumble White Pavement Strips Markings Symbol
Increase Buffer Area
REDUCED SPEED
SPEED LIMIT
AHEAD
XX
XX
W21-4
W20-5
D
R2-5b
D
KEY : Channelizing Devices Sign Location D
Distance Between Traffic Control Devices
L
Length of Longitudinal Buffer Space
D
W4-2R
D
Your Speed is
XX
Radar Triggered Speed Display
Flashing Arrow Panel
R2-1
D
G20-2
D
L
Truck Mounted Attenuator
Innovative Technologies for Hazard Control • • • • •
Vertical safetycade CB wizard alert system Radar triggered speed display White lane drop arrows Lightguard lighted raised pavement markers • Removable orange strips • Flashing slow/stop paddle
Vertical Safetycade • Designed to replace standard channelizing devices • Benefits: – Better visibilit – More positive guidance – Greater portability – Improved recoverability • Collapsible frame Vertical Safetycades
CB Wizard Alert System • Trailer-mounted system • Broadcasts a recorded message to all CBequipped motorists • Notify drivers of downstream work zones • Allows truck drivers to lower their speeds in advance of work zone
CB Wizard Advanced Warning Unit
CB Wizard Unit
Radar-Triggered Speed Display • Back-lit dynamic speed display • Standard s eed limit si n • Strobe flash (optional) – Strobe will flash when a vehicle exceeds a certain speed
• Trailer mounted
Lane Drop Arrows • Alert driver in advance of lane closure • Encourage drivers to reduce speed and move to the open lane
Lightguard Lighted Raised Pavement Markers • Provide greater visibility in work zones • Can be: – Flashing lights – Racing lights – Stead -burn li hts
With Lightguard Lighted Raised Pavement Markers
Without Lightguard Lighted Raised Pavement Markers
Removable Orange Rumble Strips • Alert motorists of a work zone • Benefits: – Highly visible – – Vibration of the steering wheel – Easy to install and remove – Reduce approach speed
Flashing Slow/Stop Paddle • Consists of a standard paddle with a strobe light mounted on its • Increases flagger visibility to passing motorists
Hazard: Flagging Operation
• 20 flaggers die each year from being Nonstandard paddle struck by a motorist height • Flagging can be hazardous as a result of: – High speed of passing traffic – Aggressive drivers in traffic stream – Insufficient stopping sight distance for motorists – • • • •
Not wearing personal protective equipment Inattention Use of nonstandard equipment Improper flagging techniques
– Hazardous environmental conditions • Fog, obstructions, wet pavements
Paddle inclined
Injury Prevention Techniques for Flaggers • Wear high visibility clothing – Appropriate for expected weather (rain gear, warm coat, etc.)
• High visibility hard hat • Use a standard SLOW/STOP paddle or flag – Flags are for emergency purposes only
Injury Prevention Techniques for Flaggers • STAY ALERT, keep focused on your work • Stand alone on shoulder in clear view, not in the open traffic lane • an an escape rou e or emergencies • Stay in communication with the other flaggers • Treat motorists with respect • Obtain proper training for flaggers, including safety training
Injury Prevention Techniques for Flaggers • Flaggers must avoid – Standing where the flagger can be hit by a vehicle – Standing in the shade, around a sharp – – – – – –
Standing in a group Standing near equipment Making unnecessary conversation Reading or day dreaming Listening to music or using ear phones Turning their back to approaching traffic
Hazard: Nighttime Traffic Control • Nighttime traffic control is more challenging – Poor visibility for drivers – – Impaired or drowsy drivers – Sleep deprived workers
Nighttime Traffic Control Injury Prevention • Use special precautions for nighttime traffic control –
-
– Flashing lights on body/clothing – Retro-reflective tape on equipment – Good work area lighting
Summary of the Module • Work zone traffic creates serious hazards for motorists and workers • Provisions of MUTCD may not be sufficient for preventing injuries/fatalities of on-foot workers • Additional injury prevention techniques should be implemented to prevent injuries to on-foot workers • Positively guiding traffic through the complex work zone is the key to safety
