2 Overview of Module 1Underlying principles of work zone traffic controlManual of Uniform Traffic Control Device (MUTCD)Features of work zone traffic controlHazards associated with work zone traffic controlInjury prevention techniquesSummaryThis module presents various safety implications of highway workers as it relates to work zone traffic control. The module begins with background information on work zone traffic control (WZTC) and presents national guidelines contained in the Manual of Uniform Traffic Control Devices (MUTCD) that currently regulate work zone traffic control. The module also discusses the potential hazards of various WZTC layouts. Casual factors of WZTC hazards are discussed as well as injury prevention techniques to abate such hazards. The module also includes recent techniques and technologies that can be applied in WZTC layouts to reduce the risk of worker injury. Finally, a summary of the module is presented to emphasize the key concepts.
3 Work Zone Traffic Control Influences drivers’ perception of riskProvides information on potential hazardsMinimizes aggressive behaviorAssists in navigationEngineering concerns for work zonesPrimary focus: Safe and efficient movement of vehicles through work zoneRelatively less emphasis on safety of construction workersA work zone traffic control system influences drivers’ perception of risk, and affects their performance through the work zone. A properly designed work zone provides drivers with information regarding the potential hazards in the work zone which allow them to respond safely to a given situation. If drivers do not perceive risk associated with a work zone/work area, they are less likely to respond as intended to the traffic control measures. This may pose severe danger, since hazards and other risks may be present, even if and when a driver does not perceive them. One example includes drivers that disregard reduced speed limits through work zones. In such cases any error on the part of the driver may have a catastrophic results. Thus, it is critical that WZTC be set up to convey the proper cues and information for drivers to travel safely through the work zone. This happens when driver expectations are met. Meeting drivers expectation also helps to reduce driver frustration and aggressive driving behavior.In the past, engineering concerns for work zones were mainly focused on the movement of vehicles efficiently and safely through the work zone, with relatively little emphasis placed on the safety of the construction workers. This can be observed in the past versions of the MUTCD. This is evidenced by the common practice of providing standard lane widths (12 ft.) for motorists even in a work zone environment. In such a condition, drivers usually perceive less risk, as evidenced by their high operating speeds. This type of driver behavior places construction workers at higher levels of risk. By providing reduced lane widths, slower speeds are typically maintained and would still be adequate to accommodate flow of traffic. Consideration of worker safety has been introduced only in recent versions of the MUTCD, beginning with the Millennium Edition of the MUTCD in 2000.
4 Type of Barrier Rigid Barriers Provide separation between Opposing traffic lanesTraffic lanes and work areaCause damage to motorists if struckConcrete barrier separating traffic lanes and work areaConcrete barrier separating opposing trafficSeveral devices are used to control the work zone traffic and separate the work area from the traffic lanes, including rigid and flexible barriers.Rigid barriers, such as temporary concrete barriers, are commonly used to separate opposing directions of travel through a work zone. They may also be used to separate the work area from the traffic lanes. This type of barrier provides workers with additional protection as compared to flexible barriers, since vehicles are not able to easily penetrate through it.
5 Type of Barrier Flexible barriers (channelizing devices) Provide nominal protection for workersFlexible and deformable, do not cause damage if struckConcrete barriers to separate work areaFlexible barriers typically include channelizing devices such as drums and cones and are deformable in nature. They are commonly used to guide traffic through a work zone and to separate the travel lanes from the work area. Since flexible barriers are not rigid like concrete barriers, they do not provide as much protection to the workers, due to their flexible and deformable nature when struck. These types of channelizing devices are however, very effective in delineating travel lanes and guiding motorists through the work zone.Flexible barrier separating traffic lanes and work areaChannelizing devices for delineation
6 Sample Road Projects and Potential Hazards Vehicles parked within work areaPassing traffic in close proximity to the on-foot worker with minimal protection from flexible barrierFlashing arrow board is not operating
7 Components of Temporary Traffic Control Zones (Source: MUTCD 2003)Advanced Warning AreaTransition AreaActivity AreaWork spaceTraffic spaceBuffer spaceTermination AreaChapter 6C of MUTCD (2003) provides the details of a typical temporary traffic control zone, which includes four basic areas: 1) advance warning area, 2) transition area, 3) activity area, and 4) termination area.In the advance warning area, the road users are informed about the upcoming work zone. In the transition area, the road users are redirected out of their normal path using strategically placed tapers. In the activity area, the work activity occurs and is comprised of the work space, the traffic space and the buffer space. In the termination area, the traffic is redirected to its normal path and extends from the downstream end of the road work area to the last temporary traffic control device.
8 Worker Safety Considerations in Work Zone Traffic Control Modifying traffic control strategies to influence drivers’ perception of riskLeads to more careful and slower drivingImproves safety for the workersExamples:Providing active warning devicesIlluminated arrow boardsReliable advisory speed limitActive message with flashersNarrower lane widthsLonger and/or wider buffer zonesRigid barriers to separate workers from travel lanesWhen worker safety is considered in the highway construction/work zone traffic control design, several modifications to the existing traffic control strategies can be made to affect drivers’ perception of a heightened risk. Such risk perception by the drivers leads to more careful and slower driving, and often improves the overall safety of the workers. These design elements compromise, to some degree, the efficiency of traffic flow by forcing drivers to reduce their speed and drive cautiously through the work zone due to the increase in perceived risk. Such elements include the use of narrow lane widths, longer and/or wider buffer zones, and traffic barriers to separate the work area from the travel lanes. The use of these traffic control techniques may reduce the potential of severe traffic crashes and injury to motorists and workers.It should be noted that when drivers perceive minimal risk, they often do not modify their driving behavior, despite the use of warning or regulatory traffic control devices in the work zone.
9 ‘Positive Guidance’ Approach May be used to improve safety in work zonesCombines highway/traffic engineering features with what rational drivers expectConsiders:Various age groups of driversComplexity of work zone information handlingLimited capability of humans for detecting, processing, and remembering informationWork zones are complex locations for drivers. They require a sound approach to address the complexity of the problem and suggest viable solutions. One of the approaches to addressing the problem is through ‘positive guidance’.The basic concept of positive guidance is to guide traffic by reasonably providing information that they expect while driving. The concept.combines highway/traffic engineering features (like roadway geometry, signs, signals, etc.) with what rational drivers expect for various situational demands. The concept considers various age groups of drivers and their associated complexities in work zone information handling while driving. Motorists often have limited capability for detecting, processing, and remembering information when needed. If too much information is provided over a short period of time while driving, motorists may not be able to take appropriate action for each piece of information, because too much is provided. Additionally, the information processing and handling ability varies with the age of the drivers. These skills tend to become more difficult as people age.
10 MUTCD – Manual on Uniform Traffic Control Devices Recognized as the national standardEnforcement agencies often adopt it by referenceProvides guidance, options and supporting materialsTo assist professionals in making decisions regarding the use of traffic control on streets and highways“The Manual on Uniform Traffic Control devices (MUTCD) is incorporated by reference in 23 Code of Federal Regulations (CFR), Part 655, Subpart F and shall be recognized as the national standard for traffic control devices installed on any street, highway, or bicycle trail open to public travel in accordance with 23 U.S.C. 109(d) and 402(a). The policies and procedures of the Federal Highway Administration (FHWA) to obtain basic uniformity of traffic control devices shall be as described in 23 CFR 655, Subpart F.” MUTCD Edition.Standards, guidance, and options for traffic control, as well as supporting documentation are contained in the MUTCD to provide professionals with information needed to make appropriate decisions regarding the use of traffic control on streets and highways. The following are the definitions of the standards, guidance, options and support as stated in the MUTCD:Standard — a statement of required, mandatory, or specifically prohibitive practice regarding a traffic control device. Standards are sometimes modified by OptionsGuidance — a statement of recommended, but not mandatory, practice in typical situations, with deviations allowed if engineering judgment or engineering study indicates the deviation to be appropriate. Guidance statements are sometimes modified by OptionsOption — a statement of practice that is a permissive condition and carries no requirement or recommendation. Options may contain allowable modifications to a Standard or Guidance.Support — an informational statement that does not convey any degree of mandate, recommendation, authorization, prohibition, or enforceable conditionThe MUTCD contains 10 main parts. Part 6 of MUTCD includes Temporary Traffic Control. The MUTCD can be found on-line at
11 MUTCD- Part 6: Temporary Traffic Control Primary function oftemporary 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”Part 6 of the MUTCD contains the following nine chapters related to temporary traffic control:Chapter 6A. – GeneralChapter 6B. – Fundamental PrinciplesChapter 6C. – Temporary Traffic Control ElementsChapter 6D. – Pedestrian and Worker SafetyChapter 6E. – Flagger ControlChapter 6F. – Temporary Traffic Control Zone DevicesChapter 6G. – Type of Temporary Traffic Control Zone ActivitiesChapter 6H. – Typical ApplicationsChapter 6I. – Control of Traffic Through Traffic Incident Management Areas
12 Temporary Traffic Control Work zones present constantly changing conditionsUnexpected by the road userCreates higher degree of vulnerability for workersThe MUTCD (2003 version) states “of equal importance to the public traveling through the temporary traffic control (TTC) zone is the safety of workers performing the many varied tasks within the work space. TTC zones present constantly changing conditions that are unexpected by the road user. This creates an even higher degree of vulnerability for the workers and incident management responders on or near the roadway. At the same time, the TTC zone provides for the efficient completion of whatever activity interrupted the normal use of the roadway”. (MUTCD, 2003 Edition, page 6A-1)
13 Temporary Traffic Control Devices Temporary traffic control (TTC) devices includeSignsSignalsMarkingsOther devicesUsed to regulate, warn, or guide road usersTemporary traffic control devices are used to regulate, warn, or guide road users, placed on, over or adjacent to a street, highway, pedestrian facility, or bikeway by authority of a public body or official having jurisdiction.These devices include signs, signals, markings, and other devices. All traffic control devices used on street and highway construction or maintenance management operations shall conform to the applicable provisions of MUTCD.
14 Types of TTC Applications Each TTC zone is differentMany variables affect the needs of each zone:Location of workDuration of workHighway typeGeometricsVertical and horizontal alignment, intersections, interchanges, etc.Road user volumesRoad vehicle mix (buses, trucks, and cars) and road user speeds“Each TTC zone is different. Many variables, such as location of work, highway type, geometrics, vertical and horizontal alignment, intersections, interchanges, road user volumes, road vehicle mix (buses, trucks, and cars), and road user speeds affect the needs of each zone. The goal of TTC in work zones is safety with minimum disruption to road users. The key factor in promoting TTC zone safety is proper judgment.Typical applications (TAs) of TTC zones are organized according to duration, location, type of work, and highway type. These typical applications include the use of various TTC methods, but do not include a layout for every conceivable work situation. Typical applications should be altered, when necessary, to fit the conditions of a particular TTC zone.Other devices may be added to supplement the devices shown in the typical applications, while others may be deleted. The sign spacings and taper lengths may be increased to provide additional time or space for driver response.Decisions regarding the selection of the most appropriate typical application to use as a guide for a specific TTC zone require an understanding of each situation. Although there are many ways of categorizing TTC zone applications, the four factors mentioned earlier (work duration, work location, work type, and highway type) are used to characterize typical applications”. (MUTCD, 2003 Edition, Section 6G.01)
15 Work DurationMajor factor in determining the number and types of devices used in TTC zonesAs per the MUTCD, five categories of work duration are defined:Long-term stationary is work that occupies a location more than 3 daysIntermediate-term stationary is work that occupies a location more than one daylight period up to 3 days, or nighttime work lasting more than 1 hourShort-term stationary is daytime work that occupies a location for more than 1 hour within a single daylight periodShort duration is work that occupies a location up to 1 hourMobile is work that moves intermittently or continuously.“Work duration is a major factor in determining the number and types of devices used in TTC zones. The duration of a TTC zone is defined relative to the length of time a work operation occupies a spot location. The five categories of work duration and their time at a location shall be (1) Long-term stationary is work that occupies a location more than 3 days, (2) 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, (3) Short-term stationary is daytime work that occupies a location for more than 1 hour within a single daylight period, (4) Short duration is work that occupies a location up to 1 hour and (5) Mobile is work that moves intermittently or continuously” (MUTCD, 2003 Edition, Section 6G.02)
16 Long Term Stationary Work (more than 3 days) Typically utilize a full range of TTC procedures and devicesProject duration far exceeds installation time of TTCTTC elements may include:Larger channelizing devices, temporary roadways, and temporary traffic barriersRetroreflective and/or illuminated devices“At long-term stationary TTC zones, there is ample time to install and realize benefits from the full range of TTC procedures and devices that are available for use. Generally, larger channelizing devices, temporary roadways, and temporary traffic barriers are used. Since long-term operations extend into nighttime, retroreflective and/or illuminated devices shall be used in long-term stationary TTC zones. Inappropriate markings in long-term stationary TTC zones should be removed and replaced with temporary markings” (MUTCD, 2003 Edition, Section 6G.02)
17 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 zonesSuch as altered pavement markings, temporary traffic barriers, and temporary roadwaysIncreased time to place and remove these devices could significantly lengthen the project, thus increasing exposure time“In intermediate-term stationary TTC zones, it might not be feasible or practical to use procedures or devices that would be desirable for long-term stationary temporary traffic control zones, such as altered pavement markings, temporary traffic barriers, and temporary roadways. The increased time to place and remove these devices in some cases could significantly lengthen the project, thus increasing exposure time. In other instances, there might be insufficient pay-back time to economically justify more elaborate TTC measures. Since intermediate-term operations extend into nighttime, retroreflective and/or illuminated devices shall be used in intermediate-term stationary TTC zones.” (MUTCD, 2003 Edition, Section 6G.02)
18 Short-Term Stationary Work (more than 1 hour within a single daylight period) Most maintenance and utility operations are short-term stationary workInclude activities that might involve different treatmentsDevices having greater mobility might be necessarySigns mounted on trucksAppropriately colored or marked vehicles with rotating/strobe lights may be used in place of signs and channelizing devicesMay be augmented with signs or arrow panelsMost maintenance and utility operations are short-term stationary work. As compared to stationary operations, short-term stationary operations are activities that might involve different treatments. Devices that are more portable might be necessary, such as signs mounted on trucks. Devices that are larger, more imposing, or more visible can be used effectively and economically. Maintaining reasonably safe work and road user conditions is a paramount goal in carrying out short-term stationary operations. Appropriately colored or marked vehicles with rotating/strobe lights may be used in place of signs and channelizing devices. These vehicles may be augmented with signs or arrow panels. (MUTCD, 2003 Edition, Section 6G.02)
19 Short Duration Work (up to 1 hour) Often takes longer to set up and remove the TTC zone than to perform the workWorkers face hazards in setting up and taking down the TTC zoneDelays affecting road users are significantly increased when additional devices are installed and removedSimplified control procedures may be warranted for short-duration workReduction in the number of devicesUse of high-intensity rotating, flashing, oscillating, or strobe lights on work vehicles“During short-duration work, it 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. Also, since the work time is short, delays affecting road users are significantly increased when additional devices are installed and removed. Considering these factors, simplified control procedures may be warranted for short-duration work. A reduction in the number of devices may be offset by the use of other more dominant devices such as high-intensity rotating, flashing, oscillating, or strobe lights on work vehicles” (MUTCD, 2003 Edition, Section 6G.02)
20 Mobile Work Often involve frequent short stops for activities Such as litter cleanup, pothole patching, or utility operations, and are similar to short-duration operationsTTC zones may includes:Warning signs, high-intensity rotating, flashing, oscillating, or strobe lights on a vehicle, flags, and/or channelizing devicesFlaggersA shadow vehicle equipped with an arrow panel or a sign following the work vehicleAppropriately 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“Mobile operations often involve frequent short stops for activities such as litter cleanup, pothole patching, or utility operations, and are similar to short-duration operations. Warning signs, high-intensity rotating, flashing, oscillating, or strobe lights on a vehicle, flags, and/or channelizing devices should be used and moved periodically to keep them near the mobile work area. Flaggers may be used for mobile operations that often involve frequent short stops. Mobile operations also include work activities where workers and equipment move along the road without stopping, usually at slow speeds. The advance warning area moves with the work area. When mobile operations are being performed, a shadow vehicle equipped with an arrow panel or a sign should follow the work vehicle, especially when vehicular traffic speeds or volumes are high. Where feasible, warning signs should be placed along the roadway and moved periodically as work progresses. Under high-volume conditions, consideration should be given to scheduling mobile operations work during off-peak hours. If there are mobile operations on a high-speed travel lane of a multi-lane divided highway, arrow panels should be used. For mobile operations that move at speeds less than 5 km/h (3 mph), mobile signs or stationary signing that is periodically retrieved and repositioned in the advance warning area may be used. At higher speeds, vehicles may be used as components of the TTC zones for mobile operations. 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. For some continuously moving operations, such as street sweeping and snow removal, a single work vehicle with appropriate warning devices on the vehicle may be used to provide warning to approaching road users. ” (MUTCD, 2003 Edition, Section 6G.02)
21 Worker Safety Considerations Key elements that SHOULD be considered to improve worker safety:TrainingWorker safety apparelTemporary traffic barriersSpeed reduction measuresPlanning of activity areaPlanning for worker safetyThe separation of the moving vehicles, equipment and construction vehicles from workers on-foot wherever possible provides a safer working place for workers.According to the 2003 Version of the MUTCD (Chapter 6D. Pedestrian and Worker Safety), key elements of worker safety and work zone traffic control management are listed as a ‘guidance’ and should be considered to improve worker safety. They include Training, Worker Safety Apparel, Temporary Traffic Barriers, Speed Reduction measures and Planning. Each of these are discussed on subsequent slides and supplemental explanations.Worker safety apparel
22 Worker Safety Consideration - TRAINING All workers should be trained on:Working safely adjacent to vehicular trafficWork zone traffic control techniquesDevice UsageSafety devicesTraffic control devicesPlacement of traffic control devicesRelevant OSHA Regulation29 CFR , Safety Training and EducationMUTCD (2003 version) states that “all workers should be trained on how to work next to motor vehicle traffic in a way that minimizes their vulnerability”.Training workers for safe working methods teaches the types of hazards associated with different types of work and how those hazards can be mitigated. One of the most promising aspect of training is that it raises the awareness about potential hazards and injury prevention techniques.The intensity and duration of training depends upon the type of work, the location of the work and the associated safety hazards.The workers assuming specific temporary traffic control responsibilities shall be trained on appropriate temporary traffic control techniques, using the safety devices and the placement of traffic control devices appropriately to meet the expectations of drivers while entering to and traveling through the work zone.
23 Worker Safety Consideration- WORKER SAFETY APPARELWorkers near motor vehicle traffic should wear bright, visible clothingRelevant OSHA Regulation29 CFR , Criteria for Personal Protective EquipmentMUTCD (2003 version) Section 6D.03 states that “all workers exposed to the risks of moving roadway traffic or construction equipment should wear high-visibility safety apparel meeting the requirements of ISEA, American National Standard for High-Visibility Safety Apparel or equivalent revisions, and labeled as ANSI , standard performance for Class 1, 2 or 3 risk exposure”.The appropriate class of safety apparel should be selected by a competent person designated by the employer.
24 Worker Safety Consideration - TEMPORARY TRAFFIC BARRIERS Barriers shall be placed along the work zone depending on:Lateral clearance of workers from adjacent trafficSpeed of trafficDuration and type of operationsTime of dayVolume of trafficRelevant OSHA Regulations29 CFR (g), Traffic Signs29 CFR , Signaling29 CFR , BarricadesMUTCD (2003 version) Section 6D.03 states that “temporary traffic barriers shall be placed along the work space depending on factors such as the lateral clearance of workers from adjacent traffic, speed of traffic, duration and type of operations, time of day, and volume of traffic”.The lateral clearance of workers from adjacent traffic is important to provide physical separation of the work area and the path of motorist traffic. When the speed of traffic is high, the barriers can be spaced relatively far apart, as compared to low speed applications. For mobile work, it is desirable to provide light weight temporary traffic barriers than concrete barriers, due to the moving nature and short duration of the work activities. If work is carried out at night, it is always desirable to have barriers with retro-reflective paint. When the traffic volumes are high, there is a higher probability that traffic may encroach into the work space if the barriers are not rigid and relatively heavy.Barriers used in temporary traffic control must conform to the MUTCD standards.Concrete Barriers
25 Worker Safety Consideration – SPEED REDUCTION MEASURES Speed of passing motorists may be influenced by:Regulatory speed zoningFunnelingUse of law enforcementLane reductionPresence of flaggersMUTCD (2003 version) Section 6D.03 states that “reducing the speed of vehicular traffic, mainly through regulatory speed zoning, funneling, lane reduction, or the uniform law enforcement officers or flaggers, should be considered”.Research has shown that regulatory speed zoning has not significantly reduced the speed in the work zones. Several other innovative methods may need to be used to significantly reduce the speed of the vehicular traffic and reduce the risk of injuries to the workers on-foot. Such methods will be discussed in later in this module.
26 Worker Safety Consideration – PLANNING THE ACTIVITY AREA Plan internal work space and activitiesMinimize the use of backing maneuvers of construction vehiclesMinimize interactions between on-foot workers, equipment and trucksMinimize worker exposure to riskDevelop internal traffic control plan and operationsRefer to “Module 2: Safe Operations and Internal Traffic Control in the Work Space”MUTCD (2003 version) Section 6D.03 states that “planning the internal work activity area to minimize backing-up maneuvers of construction vehicles should be considered to minimize the exposure to risk”.Planning and operation of the internal work activity area is a crucial part of injury prevention. On-foot workers who work around equipment with increased blind spots and frequently changing path of travel have increased exposure to risk.There are various ways of minimizing the risk of exposures of on-foot workers within a highway work area, many of which can be addressed through the preparation of an internal traffic control plan and operations. For details of planning and operating the internal work activity area for injury prevention, please refer to “Module 2: Safe Operations and Internal Traffic Control in the Work Space”, contained in this training program.
27 Worker Safety Consideration – PLANNING FOR WORKER SAFETY Hazard assessment should be conducted based on:Characteristics of work siteJob classifications required in the work areaMust comply with all relevant OSHA regulationsAssess worker risk exposures for each job site and job classification29 CFR , General Safety and Health Provisions29 CFR (b) (2)MUTCD (2003 version) Section 6D.03 states that “a competent person designated by the employer should conduct a basic hazard assessment for the work and job classifications required in the activity area. This safety professional should determine whether engineering, administrative, or personal protection measures should be implemented”.A job safety analysis (JSA) should be performed, listing all the hazards associated with a particular type of work and the methods to reduce the hazards associated with it.Frequent and regular inspections of the construction site should be conducted by a competent and designated person, as specified by OSHA [29 CFR (b) (2)].
28 Optional Worker Safety Elements Shadow Vehicle with Impact AttenuatorRoad ClosurePolice enforcementAdditional LightingSpecial DevicesRumble stripsChangeable message signsHazard identification beaconsFlagsWarning lightsIntrusion warning devicesMUTCD (2003 version) Section 6D.03 states various options for the temporary traffic control management that may be considered to improve worker safety. These options include use of a shadow vehicle, entirely closing the road to motor vehicle traffic, use of law enforcement strategies, increased lighting and/or use of special devices such as rumble strips, changeable message signs, hazard identification beacons, flags, warning lights, intrusion warning devices, etc.The MUTCD (2003 version) states that a judicial use of special warning and control devices may be helpful for complex work zones, however misuse or overuse of special devices may lessen their effectiveness. Such special devices may help reduce the speed in the work zone, which is the main cause of work zone accidents and injuries.Several special devices that can be used in work zones include:Rumble strips – to warn the motorists to reduce the speed in the work zoneChangeable message signs – to inform motorist about the work zoneHazard identification beacons – to inform motorist about work zone hazardsFlags – to warn motorists about the work zoneWarning lights – to warn motorists about the potential hazards of work zone, etc.Rumble strips
29 Optional Worker Safety Elements - SHADOW VEHICLECommon for mobile and constantly moving operationsShould be equipped with:Appropriate lightsWarning signsRear-mounted impact attenuatorA shadow vehicle is a vehicle, usually a truck, placed up stream of work area to protect on-foot workers when an errant vehicle intrudes in to the work zone.Shadow vehicles are commonly used for mobile and constantly moving operations like pothole patching, striping operations, installing temporary traffic control devices, etc.The truck follows the operation a short distance behind, giving physical protection from traffic. Its purpose is to provide protection for the crew and their vehicles involved in the maintenance activity.The minimum size for a shadow vehicle is a two-ton truck equipped with appropriate lights, warning signs and a rear-mounted crash cushion. If a collision occurs, the crash cushion softens the impact to the driver of the shadow vehicle as well as the driver of the colliding vehicle. This is because a significant amount of energy is absorbed by the rear mounted crash attenuator of the shadow vehicle when traffic hits it.Shadow vehicle with rear mounted crash attenuator
30 Truck Mounted Attenuator Crash with a truck with a truck mounted impact attenuatorThe picture in the top shows a crash when a vehicle hits a shadow vehicle with a truck-mounted attenuator and the picture in the bottom shows a condition when a vehicle hits a shadow vehicle without a truck mounted attenuator.From the top picture, it can be inferred that a significant amount of energy has been absorbed by the break of the attenuator that will reduce the severity of injury to the shadow vehicle (truck) driver as well as the car driver after the crash.Crash with a truck without an impact attenuator
31 Optional Worker Safety Elements - ROAD CLOSURE Reduce worker vulnerability to risk of injuryProvide more spacious areas to conduct work activitiesEliminate threat of intruding vehicles from passing trafficAid in faster projectcompletionA roadway can be completely closed if alternate routes are available to handle the road traffic. One of the most important benefits of full closure of roadways is the reduced worker vulnerability. When the road is completely closed, the risk to the flaggers as well as the workers working close by the moving traffic is eliminated.Fully closing the roadways for construction may also maximize the work space available for construction and can increase productivity. The duration of the project will be reduced since the contractor will have more space to expedite his work.Freeway closure for one direction of traffic
32 Optional Worker Safety Elements - USE OF POLICE ENFORCEMENTPolice units may be stationed in a work zone to:Heighten awareness of passing motoristsImprove safety through work zone by enforcing speed limitsFor construction projects that have relatively short durations and for work zones that are highly vulnerable, law enforcement officers may be stationed in appropriate locations to heighten the awareness of passing vehicular traffic.Studies have shown that this is especially helpful in reducing the vehicular speed through the work zone since the presence of police officers will cause the careless drivers to reduce their speed due to the fear of receiving a citation. This will significantly reduce the encroachment of the speeding errant vehicles into the work zone.
33 Optional Worker Safety Elements - LIGHTING Additional lighting should be provided at work zones that operate during the nightNighttime work requires extra caution due to:Poor night time visibilityImpairment of workers related to fatigueImpairment of driversThe MUTCD (2003 version) states that “for night time work, the temporary traffic control zone and approaches may be lighted”.Lighting may be extremely important depending on the location and geometric condition of the roadways near a work zone. Work zones with limited sight distance and unusual geometry should be sufficiently illuminated to minimize the hazards of errant vehicles intruding into the work space, thus reducing the risk for workers at night.Lighting is also important in the work zone since some workers may not be equally alert at night due to disruptions in their sleeping habits.Nighttime work is common in highway/street construction projects
34 Sample Work Zone Traffic Control Layout For a Single Lane Closure as per MUTCDPre-construction speed limit is 70 mphW21-4W205R25bW42R1G202REDUCEDSPEEDXXAHEADLIMIT1400’700’600’FlashingArrow PanelMedianThe figure shows a standard work zone traffic control layout, as per the MUTCD. The signs and pavement markings portrayed in the figure show typical standards suggested for work zone traffic control.Several state-of-the-art practices have been developed to reduce work zone injuries by modifying the work traffic control layout. Such plans include the elements as shown on the previous slide and additional elements, as discussed later in this module.KEYNote: Distance in feet, drawing not to scaleChannelizing DevicesSign Location
35 Work Zone Traffic Control MUTCD provides minimum requirementsVarious demanding situations may warrant enhanced safety precautions, such as:Nighttime workInclement weather conditionsUnusual roadway geometry and environmentCombinations of the aboveGoing beyond existing standards/guidelines may be necessary to ensure highest levels of traffic and worker safetyThe standards contained in the MUTCD are minimal requirements. They may work satisfactorily for normal conditions, but may need to be expanded for more demanding situations.In work zone traffic control, several demanding situations exist, where merely satisfying the minimum standards may be insufficient depending upon the situation; such as:Nighttime work is more demanding due to reduced visibilityInclement weather conditions causing low visibilities and/or slippery road surfacesUnusual geometrical conditions and environments that violate drivers expectationsCombinations of the above situationsIn these situations, going beyond standards may be extremely necessary to ensure highest level of traffic and worker safety in the work zone.
36 Work Zone Traffic Control Hazards and Injury Prevention Techniques
37 Hazards of Work Zone Traffic Control Common HazardsPassing motorist intruding into the work spaceHazards related to flaggingNighttime hazardsHazards related to work zone traffic control can be broadly categorized into three basic types of hazards including passing motorists intruding into the work space, flagging hazards, and nighttime traffic control hazardsPassing motorists intruding into the work space may occur for various reasons, some of which include high speed of motoring traffic, improper geometry of lane shift, improper traffic control and others.Flagging is an inherently hazardous job since the flaggers stand close to the moving traffic and a lack of continuous alertness can jeopardize their safety any time.Quite a bit of construction work is done at night in an effort to avoid the higher volume daytime hours and associated traffic delays, which may be the only positive benefit of night work. If traffic can be maintained at a reasonable level, it is generally preferred to conduct work during the day for the following reasons:Night work is inherently more hazardous due to the reduced visibility and the much higher percentage of impaired driversProduction and quality can suffer to some extent because of the difficulty of working under low light and portable light conditions
38 Hazards of Work Zone Traffic Control Causal FactorsConditions unexpected by the moving trafficViolation of driver expectancyConditions unexpected by the workersAggressive driversUnplanned work zone/activityInjuries can occur due toMotorists’ mistakesWorkers’ mistakesDeficiencies in the work zone environmentMost of the hazards associated with work zone traffic control are caused either by conditions unexpected by the moving traffic and conditions unexpected by the workers.When the expectations of drivers are violated in a work zone, either due to improper planning or inappropriate operation, serious traffic conflict can occur creating a potential hazard and consequent injuries.Similarly, workers on-foot may experience unexpected conditions in the work zone due to speeding vehicles (aggressive drivers) in spite of the warning and regulatory devices installed in the work zone. This is more pronounced when the work zone and activities are not adequately planned.Injuries associated with work zone traffic control may be caused due to mistakes/errors on the part of motorists or workers, as well as deficiencies in the work zone environment. To reduce the injuries associated with traffic control in the work zone, proper planning and operation is essential.
39 General Preventive Measures On-foot workersUse portable radio communication equipmentTraffic ControlUse additional warning devicesMaintain signs properlyUse Proper lane markingsFlaggersUse a flashing slow/stop paddleLaw enforcementUse officers and radar surveillance for traffic speed controlSeveral preventive measures can be used in addition to the requirements of the MUTCD. Some examples are:Using additional warning signs and traffic control devices in addition to the minimum standards stated in the MUTCD. Signs and traffic control devices are selected based on the requirements of the specific site and potential hazards in the work zone, depending upon the speed of the motoring traffic and type of the roadways.Flaggers may use a flashing slow/stop paddle that enhances safety, making the motoring traffic more alert.On-foot workers and equipment operators may use portable radios to increase communications and coordinate work activitiesUsing law enforcement officers and radar surveillance for traffic speed control in the work zone can help minimize speeding violations in the work zone, and discourage aggressive drivers.
40 Hazard: Passing Motorists Intruding Into Work Space Causes of HazardsHigh approach speedImproper geometry of the lane shiftImproper traffic controlInadequate information systemNo physical separation between work space and traffic laneThe basic causes of the intrusion of the motoring traffic into the work zone include high speed of passing vehicles, improper geometry of lane shift, and/or improper traffic control for a given condition. Measures for abating such hazards may include the use of proper speed reduction techniques, proper design of lanes/tapers within the work zone, provision of effective traffic control measures in the work zone.Several methodologies can be used to reduce the speed and warn the drivers, such as orange rumble strips, white lane drop arrow, radar triggered speed display and others. The work zone lanes should be designed properly to facilitate smooth transition for all types of drivers. Efficient use of various traffic control devices is critical in preventing moving traffic from intruding into the work zone.Hazard mitigation measuresUse of proper speed reduction methodsProper design of the wok zoneProvide effective traffic control measures
41 Hazard: Passing Motorists Intruding Into Work Space Preventive Measures:Exceed minimum standards/guidelines for traffic controlRumble stripsLane drop arrowsLighted raised pavement markersRadar triggered speed displaySafety warning systemCombinations of the aboveAdditional traffic control devices can be used to reduce the speed of the motoring traffic as well as the risk of injuries to on-foot workers. These additional traffic control devices include: rumble strips, lane drop arrows, lighted raised pavement markers, radar triggered speed display, truck mounted attenuator, safety warning system, etc.The photograph on the previous slide shows a truck that is dangerously close to intruding into the work zone. The shift of the lanes into the work zone is abrupt, and hence, when the higher-speed traffic approaches the lane shift, there is a higher chance of intrusion into the work zone. This is especially true for large vehicles with a larger turning radius. The photograph also shows that drums are being used as channelizing devices. They are very light and offer no resistance to the intruding traffic.Additional traffic control devices can be used after analyzing the necessity of the devices by a competent work zone traffic control specialist. A diagram showing some of these additional traffic control devices is shown in the following slide.Truck may intrude into the work zone
42 Sample Work Zone Traffic Control Layout With Additional Safety Features For a Single Lane ClosureRetroreflective RaisedPavement MarkersTemporary RumbleWhite PavementYourYourRadar TriggeredIncrease BufferSpeed isSpeed isStripsMarkings SymbolAreaXXXXSpeed DisplayREDUCEDSPEEDXXAHEADREDUCEDREDUCEDSPEEDLIMITXXAHEADSPEEDSPEEDSPEEDSPEEDXXXXLIMITLIMITAHEADAHEADXXXXThe figure on the previous slide shows an example for the installation of additional safety features to encourage reduced speeds of the motoring traffic and reduce the risk of potential worker injury.The additional safety improvements installed include the following:Temporary rumble strips (orange color) upstream of work zone are intended to discourage motorists from speeding when approaching the work zoneWhite lane shift arrows to inform the motoring traffic that the lane is about to end and they are required to change lanesRetro-reflective raised pavement markers to guide the motoring traffic to stay in the designated lane during the work zoneIncreased buffer zone between the through lane and the work area to reduce the threat to the on-foot workers working nearbyRadar-triggered speed display indicates the speed of the motoring traffic and encourages them to reduce their speedTruck mounted attenuator provided at the beginning of the work area to dissipate the kinetic energy of a colliding vehicle if a collision occurs, thus reducing the risk of severe injuriesFlashingW21-4W20-5R2-5bW4-2RR2-1G20G20--22Arrow PanelDDDDDLDDTruck MountedAttenuator
43 Innovative Technologies for Hazard Control Vertical safetycadeCB wizard alert systemRadar triggered speed displayWhite lane drop arrowsLightguard lighted raised pavement markersRemovable orange stripsFlashing slow/stop paddleRecently, several new methods and technologies are being used in construction work zones, as listed on the previous slide. Details of each of these innovations are described on the following set of slides.
44 Vertical Safetycade Designed to replace standard channelizing devices Benefits:Better visibilityMore positive guidanceGreater portabilityImproved recoverabilityCollapsible frameVertical safetycades may be used in place of standard channelizing devices.They are more visible than standard channelizing devices. Higher visibility may translate into improve driver actions, as a result of increased reaction time. This helps in reducing driving errors related expectancy violations.They also provide additional guidance, as the arrows on the vertical safetycades indicate the direction of traffic to merge at a lane shift.They are light and portable, so it is easy for the workers to place and remove them. In lieu of the following:This may reduce worker reluctance to ensure they are set up and maintained properlySince they have collapsible frames, they are easily recoverable for repeated useVertical Safetycades
45 CB Wizard Advanced Warning Unit CB Wizard Alert SystemTrailer-mounted systemBroadcasts a recorded message to all CB-equipped motoristsNotify drivers of downstream work zonesAllows truck drivers to lower their speeds in advance of work zoneCB Wizard Advanced Warning UnitCB Wizard UnitIn the citizens band (CB) wizard alert system, a trailer-mounted system broadcasts a recorded message to all CB equipped motorists. The system is commonly used to notify the drivers of upcoming work zone activities. The system broadcasts a pre-recorded message, approximately seven to ten seconds long, to warn drivers of the roadway conditions over a CB channel, usually channel 19. The message contains information about downstream construction activities or other conditions associated with reduced traffic speeds.This can help truck drivers in lowering their speeds upstream of the work zone. This in turn reduces the potential of trucks intruding into the work zone as a result of driving at excessive speeds for the given conditions.
46 Radar-Triggered Speed Display Back-lit dynamic speed displayStandard speed limit signStrobe flash (optional)Strobe will flash when a vehicle exceeds a certain speedTrailer mountedRadar-triggered speed displays are used to induce reaction to spontaneous speed of the moving traffic in the work zone. Since the motorists know what their speed is in the work zone, they will be encouraged to adjust their speed according to the speed as observed by an individual driver. The display is positioned such that it can show the speed of each vehicle, one at a time.
47 Lane Drop Arrows Alert driver in advance of lane closure Encourage drivers to reduce speed and move to the open laneWhite lane drop arrows are used to alert drivers just upstream of the work zone (where the taper starts). The arrows inform motorists that the lane is closing and directs drivers in the closing lane to safely merge to the continuous lane.Since the drivers are able to see the bright white arrows for lane drops, they will reduce their speed and merge to the open designated lane(s) as indicated by the direction of the arrow.Please note that the white lane drop arrows may be installed with other traffic control and channelizing devices, such as vertical safetycades or standard channelizing devices, flashing arrows, flaggers, etc.
48 Lightguard Lighted Raised Pavement Markers Provide greater visibility in work zonesCan be:Flashing lightsRacing lightsSteady-burn lightsLightguard lighted raised pavement markers provide better delineation for the night time traffic. They also provide more visibility in the work zones at night.The lighted raised pavement markers can be provided with flashing lights, running lights or steady-burn lights.The photographs in the previous slide show a comparison of the delineation of a cross-over with and without the Lightguard lighted raised pavement markers.Without Lightguard Lighted Raised Pavement MarkersWith Lightguard Lighted Raised Pavement Markers
49 Removable Orange Rumble Strips Alert motorists of a work zoneBenefits:Highly visibleRepeating rumble soundVibration of the steering wheelEasy to install and removeReduce approach speedRemovable orange strips work similarly to typical shoulder rumble strips. They are provided up stream of the work zone to alert motorists of the changing roadway conditions. The benefits of the orange rumble strips include:They are highly visible from a far, so motorists are aware of the changing roadway conditionsAlerts drivers through a repeating rumble sound and vibrationThey are are easy to install and remove
50 Flashing Slow/Stop Paddle Consists of a standard paddle with a strobe light mounted on its faceIncreases flagger visibility to passing motoristsThe flashing SLOW/STOP paddle consists of a standard SLOW/STOP paddle with a strobe light mounted on its face. This increases the flagger visibility to the passing motorists and hence encourage the drivers to reduce the speed.Typically, flaggers have used signs with the word "stop" on one side and "slow" on the other to control traffic in temporary work zones. Drivers, distracted by sights along the road, don't always heed the signs, with potentially dangerous consequences for maintenance workers. To better grab motorists' attention, the flashing stop/slow paddle features high-intensity lights that are visible both night and day. If a motorist does not appear to be following the flagger's instructions, the flagger can switch on the flashing lights, thus alerting the diver to the message on the paddle and possibly preventing an accident. Several different models of the flashing stop/slow paddle are now commercially available.
51 Hazard: Flagging Operation 20 flaggers die each year from being struck by a motoristNonstandard paddle heightFlagging can be hazardous as a result of:High speed of passing trafficAggressive drivers in traffic streamInsufficient stopping sight distance for motoristsImproper procedures used by flaggersNot wearing personal protective equipmentInattentionUse of nonstandard equipmentImproper flagging techniquesHazardous environmental conditionsFog, obstructions, wet pavementsFlagging can be hazardous due to the high speed of motoring traffic, aggressive drivers or angry drivers do not follow the rules, the stopping sight distance for motorists is not sufficient due to lack of proper work zone design or excessive speed of the aggressive drivers, flaggers are not following the standard procedures and methods for flagging, the work environment is such that it becomes an obvious threat to flaggers, like reduced visibility due to fog, rain, or insufficient lighting, flaggers staying closer to other objects like electric poles, shade of a tree, etc.Paddle inclined
52 Injury Prevention Techniques for Flaggers Wear high visibility clothingAppropriate for expected weather (rain gear, warm coat, etc.)High visibility hard hatUse a standard SLOW/STOP paddle or flagFlags are for emergency purposes onlyFlaggers should wear high visibility clothing that is appropriate for expected weather conditions (rain gear, warm coat, etc.). A hard hat must be worn all the time by the flaggers. High visibility hard hats enhance the safety of the flaggers.Flaggers must use standard SLOW/STOP paddles or flags and must conform to the MUTCD. For details of standards, please refer to MUTCD, 2003.
53 Injury Prevention Techniques for Flaggers STAY ALERT, keep focused on your workStand alone on shoulder in clear view, not in the open traffic lanePlan an escape route for emergenciesStay in communication with the other flaggersTreat motorists with respectObtain proper training for flaggers, including safety trainingFlaggers should stay alert all the time, and keep focused on their flagging job. Flaggers should not do any extra work other than flagging.The flaggers should stand alone on the shoulder of the road in a clear view of the motorists. They should not stand on the open traffic lane and try to stop the traffic.The flaggers should plan an escape route for emergencies so that they can leave in emergency situations.The flaggers should remain in communication with other flaggers and be properly informed of any possible hazards or impending emergencies.The flaggers should treat motorists with respect and courtesy. Do not respond to motorists in anger. If any motorists do not obey flaggers, inform law enforcement officers immediately. Do not try to enforce the law yourself. Remember, the duty of the flaggers is to flag and guide the traffic, not to enforce the law.Only certified and trained flaggers shall be used for flagging. Untrained flaggers present hazards to themselves, as well as to others.
54 Injury Prevention Techniques for Flaggers Flaggers must avoidStanding where the flagger can be hit by a vehicleStanding in the shade, around a sharp curveStanding in a groupStanding near equipmentMaking unnecessary conversationReading or day dreamingListening to music or using ear phonesTurning their back to approaching trafficFlaggers must avoid dangerous behaviors that impact their safety, as well as the safety of others. The flaggers should avoid the following actions:Standing where the flagger can be crushed. This may be on the path of internal traffic or external traffic in the work zoneStanding in the shade, around a sharp curve where the motorists can not see the flaggerStanding in a group, thus causing confusion to motoristsStanding near equipment where the motorists may not notice the flaggerMaking unnecessary conversation, not focusing on workReading or day dreaming that impairs the flaggers’ alertnessListening to music or using ear phones distracting flagger from the jobTurning back to moving traffic that can cause reluctance to react quickly in case of emergencies
55 Hazard: Nighttime Traffic Control Nighttime traffic control is more challengingPoor visibility for driversPoor visibility for workersImpaired or drowsy driversSleep deprived workersNighttime traffic control in work zone is more challenging due to the poor visibility for drivers and workers, higher chance of drivers being impaired or drowsy, fatigues workers.Reduced visibility during the night not only impacts the safety of workers but also the safety of drivers. Visibility reduces the reaction distance required for safe action, like slowing or stopping. Accomplishing nighttime traffic control is especially challenging because of the impaired or drowsy drivers in the traffic stream. This also affects other drivers. Besides, the sleep disruption of workers can also affect the alertness and focusing in the work.
56 Nighttime Traffic Control Injury Prevention Use special precautions for nighttime traffic controlRetro-reflective clothingFlashing lights on body/clothingRetro-reflective tape on equipmentGood work area lightingSpecial precautions shall be implemented to prevent injuries during nighttime traffic control. These may include use of retro-reflective clothing for workers including flashing lights on body/clothing, retro-reflective tape on equipment, and increased lighting in the work area.
57 Summary of the ModuleWork zone traffic creates serious hazards for motorists and workersProvisions of MUTCD may not be sufficient for preventing injuries/fatalities of on-foot workersAdditional injury prevention techniques should be implemented to prevent injuries to on-foot workersPositively guiding traffic through the complex work zone is the key to safetyThis module discussed the several hazards associated with the work zone traffic control. The provisions stated in the MUTCD (2003 version) was explained in the module. It is understood that the standards mentioned in the MUTCD (2003 version) are not sufficient for complex work zone situations. In several instances, recent technologies and the newly adopted provisions of work zone traffic control techniques like temporary orange color rumble strips, white lane drop arrows, radar triggered speed display, flashing STOP/SLOW paddle, etc. are very useful in positively guiding the work zone traffic.This module discussed the hazards like passing motorists intruding into the work zone, flagging hazards and night time traffic control hazards in detail and injury prevention techniques for such hazards.This module can not be an exhaustive detail of the hazards and injury prevention techniques since each work zone is unique in itself. Hence, the material explained in this module should be adopted with the specific work zone where ever it is necessary to apply the techniques stated in this module. A concept of positively guiding the work zone traffic to prevent on-foot workers from injuries and fatalities is the key element of this module.