Variety of tools available to reduce risk
Oregon Department of Transportation employee Tim Swift said it was just a few years ago that he was working on a section of Oregon 18 between Sheridan and Willamina when he got side-swiped by a passing vehicle, injuring his hip. As assistant manager for the Salem-area district, Swift and his coworkers have seen this happen countless times.
“Most of the time, drivers who pass through work zones at dangerous speeds say they never saw signs to slow down,” Swift said.
Unfortunately, injuries like Swift’s, near misses, and even fatalities are far too common for highway workers around the country. However, there are ways to reduce interaction between traffic and workers through positive protection or limiting exposure.
Positive protection defined
Positive protection devices are designed to physically prevent vehicles traveling through highway work zones from entering space occupied by workers, equipment, materials or roadside hazards. Examples include portable concrete or steel barriers, plastic ballast-filled barriers (usually sand or water), mobile barriers and truck-mounted attenuators, among others.
Portable concrete barriers and ballast-filled barriers are commonly used throughout Oregon to protect workers and travelers. Mobile barriers, which can be used in short-term or mobile work zones, are gaining in popularity, especially for maintenance projects. Oregon has deployed these devices in several areas of the state including as part of a research project in 2012–13. The report concluded that mobile barriers are “found to be an effective and beneficial tool for ODOT Maintenance crews.”
ODOT also regularly considers the potential for detouring traffic around long-term work zones as a means for providing maximum worker protection from traffic.
Policies provide guidance
Recent updates to the federal Work Zone Safety and Mobility Rule (23 CFR 630, Subpart K) require agencies to establish policies, procedures and guidance for the consideration and use of positive protection in their work zones. States have taken slightly different approaches to this. Kansas Department of Transportation’s procedure includes specific guidance for different exposure types and includes a flowchart to help decide if positive protection is needed and under what circumstances, while Texas Department of Transportation’s procedure includes justification criteria for different types of positive protection.
“We can’t recommend a particular approach, but the use of a flowchart approach seems beneficial from my perspective since it provides a logical way to analyze based on the factors found at the site,” said Nick Fortey, FHWA safety engineer.
ODOT incorporates the FHWA direction into its current design policies and training program. The ODOT Traffic Control Plan Design Manual and two-day “TCP Design Workshop” class include guidance on considering and evaluating various approaches to optimize worker and traffic safety.
Limiting exposure defined
Limiting or eliminating workers’ exposure to traffic is another way to improve safety. The fewer times motorists encounter work zones, the fewer chances there are for work zone crashes to occur. There are several different strategies available including:
- Reducing the length of time a work zone is in place or reducing the number of work zones.
- Using full road closures and detours
- Performing night work (when fewer vehicles are on the road).
- Using demand management programs to reduce volumes through work zones.
All of these strategies have been used in Oregon. During the Elk Creek Bridge replacement project in Elkton, prime contractor Slayden Construction used a rapid replacement technique where workers were completely off the roadway while building the new bridge and a full closure over a weekend was used to slide the new bridge into place. Directional road closures were used in Portland for paving projects on Interstate 405 and Interstate 84.
Demand management programs reduce the total amount of traffic in a work zone by encouraging reductions in trips (carpools, transit, bike/walk, etc.). This strategy has been used on projects in the Portland and Eugene areas with success.
What about mobility?
Developing a traffic control plan that takes freight mobility concerns into account, yet also provides enough space for contractor operations and a safe environment for workers can be tricky. Hard barriers can be difficult for wide loads to negotiate when road widths are narrowed. ODOT’s mobility program helps to forecast potential problems, encourage communication and resolve issues.
“Our mobility guidelines help to ensure that we maintain width and height standards on freight routes whenever possible,” said Tony Coleman, ODOT Region 1 mobility liaison. “But dialog is the most important thing. Keeping the conversation flowing so that we can address safety and mobility is something that we and our partners work really hard on.”
Specific application dependent on many factors
Reducing interaction between traffic and workers through positive protection, or limiting exposure can be done in many ways. Choosing the right tools for the right circumstances is essential.
“The specific application of positive protection and positive separation are very much dependent on each project’s scope of work, facility type, location, duration and other factors related to the management of risk,” said ODOT Traffic Control Plans Engineer Scott McCanna.
Along with its current practices and means of providing positive protection, ODOT continues to explore new, innovative devices and technologies to provide an efficient, effective and safer work zone for workers and highway users.
This is the sixth in our series of articles on taking a fresh look at work zone safety.