Utility Work Zone Safety Guidelines and Training: State-of-the-Art Synthesis and State-of-the-Practice Synthesis

4.0 CONCLUSIONS

Utility work zone traffic control often poses some unique challenges to the local highway agencies as well as the utility workers due to their transient and unpredictable nature of work and the available guidelines for temporary traffic control being very general in nature. The following represents the conclusions based on the existing literature, their conclusions/observations and also the responses from the current practices survey:

  1. Definitions of duration of work related to utility work zones are based on various time categories included in the MUTCD (1). Long-term stationary and intermediate-term stationary seem to be compatible with risks associated with such work zones. Mobile operations are also quite clear in meaning and intent; however, short-term stationary and short duration work seems to be based on somewhat arbitrary time categories. The utility work categories defined in terms of their functionality and safety risks along with the time based definitions in the MUTCD may assist the highway agencies, utility companies and contractors to have better uniformity of traffic control and to minimize traffic crash and injury risks.
  2. The number of fatalities in utility work zones is relatively low as compared to construction and maintenance work zones (5, 15) which may be in part due to errors and inconsistencies in reporting crashes. The number of fatalities for utility work zones has remained relatively consistent (8 to 21 fatalities per year) for the past 12 years (5). These fatalities can be avoided by providing proper safety training to the workers and providing sufficient warning of the work zone through temporary traffic control to the motorists. Studies have shown that most work zone crashes and injury crashes took place in interstate and major arterial work zones (8, 10, 15), most work zone crashes were rear-end, sideswipe or fixed object (8, 10, 15, 16), most crashes occurred in the activity area of the work zone (10) and heavy vehicles were involved in a higher percentage of work zone crashes as compared to non work zone crashes (15, 16).
  3. Urban work zones face unique challenges due to the frequency of intersections and multiple distractions from commercial displays (17). Urban work zones also have high speed variations, high volumes, frequent turning movements, frequent crossing movements and frequent traffic signals which provide challenges for the temporary traffic control (18). These issues result in a need for modifications to the temporary traffic control plans. Some improvements that should be considered include providing large street name signs and business signs so the motorists can see them far in advance (17, 18), providing cones on the edge of curves to improve visibility and recognition (17), using arrow panels for lane closures when speed and volumes are high, only reducing speed when completely necessary since most motorists do not follow speed limits unless they perceive a safety risk or threat of enforcement and providing raised pavement markings because they are more visible and easily removable (18). Adequate information should be provided to the motorist to help alleviate the problems that arise due to the urban environment.
  4. Utility work most often occurs on the shoulder or further off the shoulder of roadways in urban areas (3). They mostly occur on local roads with moderate speeds over a short distance (3). The location of the utility work is very important in determining the type of traffic control that should be used. Different risks are associated with different locations of work zones and different speeds and volumes of the roadways on or near the work zones. The type of temporary traffic control may be determined based on the type of utility work being completed, rather than the duration of the work because it may take different lengths of time to complete the same type of utility work.
  5. Human Factor issues related to the road users through the work zones have been studied (21, 22, 23) and the researchers have found that they play an important role in the way the driver understands and reacts to the information given about the work zone. Drivers should only be given information they need so that they can gather the information and correctly react. If a driver is overloaded with information, they may become confused and miss information that may have been important for safe operation of their vehicle through a complicated driving environment (21). The amount of information that is given to a driver should be adequate to help the driver perform their task of driving without causing confusion (23).
  6. Since the utility work is normally short in duration, most workers do not want to spend too much time setting up the temporary traffic control especially since the traffic control set¬up may sometimes take longer than the actual work (1). The safety risks associated with setting up the traffic control are very high because the workers are directly exposed to the passing vehicles, which results in a higher chance of the worker being involved in a crash.
  7. Traffic control devices in the short duration work zones were evaluated by several researchers to determine the safety of both the motorists and the workers (26, 27, 28, 29). New and innovative traffic control devices should be used for mobile and short duration work zones and training should be provided on the use of each device to ensure the device is properly and safely used (27). It was found that fluorescent yellow-green worker vests and hard hat covers, portable variable message signs and speed display trailers had a positive impact on maintenance work zones (28). Guidelines have also been developed for the type of protection vehicle that should be used for mobile and short duration work zones based on the roadway type, volume and speed limit (29).
  8. Warning lights and warning light systems were evaluated to determine the effect of these lights on the safety of work zones (30, 31, 32, 33). When using warning lights on vehicles, considerations should be given including the color of the lights should be yellow when used on work vehicles unless otherwise noted, there should be two warning lights when mounted on trucks or other equipment to ensure visibility all the way around the vehicle, when possible flashing/rotating incandescent lights are recommended since they are more visible in terms of depth perception, single warning lights should be mounted in the center of a vehicle’s roof, and four-way emergency flashers and retroreflective vehicle markings cannot replace the warning lights, but may be used as a supplement (30). A combination of amber and blue lights is the most effective color combination (31) and flashing lights are more effective than rotating and strobe lights (33). There is a need for national guidelines and standards for warning lights (32)
  9. Arrow panels should be used as advanced warning devices for work zones (34, 35). The arrow panels should use a diamond display instead of the line and four-corner display when used to warn motorists of work on the shoulder or side of a roadway (35). The arrow board should also consist of a single on-off blinking mode and the brightness should be adjusted as to be bright enough for the motorist to see, yet not cause a glare (34).
  10. The safety of the workers is a very important aspect of any work zone. The main reason why crashes occur involving the utility worker is because the worker may not be seen by a motorist traveling through the work zone or by another worker operating construction vehicles or equipment. In order to avoid these crashes, workers should wear safety clothing that makes them clearly visible to all others. The safety clothing should be fluorescent red-orange unless the work zone contains other orange equipment and cones, then the worker should wear fluorescent yellow-green, fluorescent red-orange with yellow-green or fluorescent pink (38). The luminance of the safety clothing should be bright enough so the worker can be seen from far distances and from all angles (39).
  11. Innovative traffic control devices for temporary traffic control included vehicle control systems for shadow vehicles (36) and guidelines for using truck mounted attenuators (37). The vehicle control systems researched involved fully automated and tele-operated control (36). The guidelines for using truck mounted attenuators were based on location and type of work, special hazards, access control and the speed limit. They are recommended on freeways with no formal lane closure or shoulder closure and on non freeways with no formal lane closure and speeds greater than 50 mph (37).
  12. There are currently multiple training programs available on the topic of work zone safety (5, 41, 42, 43, 46, 47, 48, 49, 50); however, there are few training programs and training materials that deal specifically with utility work zones (40, 44, 45, 51). Training for construction, maintenance and utility work zones may not be combined with general work zone training. Each type of work zone has special features and characteristics that should be addressed separately. The training programs for utility work zones should focus on the challenges associated with the utility work and be more specifically focused on the need of the utility workers and others involved in the utility work zones.
  13. A current practices survey was distributed to multiple utility companies and state DOTs to determine their current practices for utility work zones and traffic control standards. The results showed that most utility companies and state DOTs claimed to have established standards or guidelines for utility work zone traffic control. Only two of the state DOTs actually have separate utility work zone traffic control manuals. All others refer to or echo the language of the MUTCD and state design manuals as their guidelines. Most states do not have different standards based on the type of utility work, but do have different standards based on the duration of work, location of work and the roadway type. Sixty percent of the utility companies and 25 percent of the state DOTs have specific guidelines for emergency traffic control. Over 40 percent of the companies and DOTs have experienced crashes related to utility work zones in the past five years and one-third were faced with tort liability cases. Thirty-three percent of the utility companies had been cited for a violation by the local Occupational Safety and Health Administration (OSHA) for either personal protective requirement violation or OSHA general requirement violation. Twenty-five percent of the state DOTs place responsibility for reviewing and approving the temporary traffic control plans on the contractor or utility company. The other state DOTs place the responsibility on either the traffic or permits engineer. Eighty-five percent of the utility companies and 71 percent of the state DOTs currently offer training programs geared towards utility work zone traffic control for their employees.

The state-of-the-art literature review and current practices survey will aid in the next step of the project, which involves conducting a gap study and needs assessment of the existing utility work zone safety and mobility guidelines and training. All gaps in the current practices of agencies will be addressed and examined to determine the relevance of the gap with regard to worker and motorist safety and whether the gap represents a need in this program.

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