Work Zone Risk Factors For Rear-End and Sideswipe Crashes

The third TRB paper I would like to discuss is paper number 14-3840: “Work Zone VS. Non-Work Zone: Risk Factors Leading to Rear-End and Sideswipe Collisions” by Claire Silverstein, Justin Schorr and Samer Hamdar of George Washington University.

I co-chair California’s work zone safety committee. One of our members, Pat Fyhrie of U. C. Davis Advanced Highway Maintenance & Construction Technology (AHMCT) research group has been reconstructing work zone crashes to better understand where the majority of crashes occur. She has found that most are rear-end or sideswipe crashes and a majority of those occur alongside the work area within the work zone.

This TRB paper takes this a step further. They have found that rear end and sideswipe crashes occur in work zones more often when “there is no precipitation, during daylight conditions, with limited roadway curvature, and when increasing number of lanes and speed limits.” In other words, the results are counter-intuitive. The “safer” the work zone appears, the less safe they become.

This makes more sense when you look at it from the driver’s perspective. He or she will slow down when it rains, or when the lanes are narrowed or shifted, or when they are traveling near temporary concrete barrier. But when the road straightens out and opens up, it’s pedal to the metal time!

The paper comes to the conclusion that there are many opportunities to use technology to help prevent these crashes. Some of that technology will (eventually) be in-vehicle. Automated enforcement should be considered. But a third area of opportunity is work zone ITS. The authors write, “potential ITS applications should be targeted at creating safer traffic flow conditions by encouraging safer driver maneuvers.”

Queue warning systems, Variable Speed Limit systems, and Dynamic Merge systems come quickly to mind. All three are low cost systems that are easy to deploy and that help to smooth traffic flow and reduce speed variance – the primary cause of both rear-end and sideswipe crashes. V2V systems will one day do this automatically. But that day is still many years away. Work zone ITS can do it today, dependably and cost effectively.