Improving Compliance with Work Zone Speed Limits: Effectiveness of Selected Devices

Thousands of crashes occurring in work zones each year lead to numerous fatalities and injuries. The sizeable portion of these crashes attributed to excessive speed emphasizes the need to motivate drivers to comply with speed limits in work zones. A recent research project was conducted to determine effective measures to motivate and encourage drivers to observe posted speed limits in work zones. Three devices were tested in that project: a speed display trailer, changeable message sign with radar, and orange-border speed limit sign. Results from field testing indicate that devices with the ability to display drivers’ speeds have considerable potential for reducing speeds and improving compliance. Orange borders greatly improve the visibility and conspicuity of speed limit signs, but they do not have a consistent measurable effect on compliance. In the absence of active enforcement, data from this project indicate that drivers are likely to drive as fast as they feel comfortable, regardless of the posted speed limit.