The strips, which are raised or grooved patterns in the pavement, create an audible rumbling sound and a vibration in the steering wheel when a vehicle drives over them. Most crashes involving drowsy drivers occur when a vehicle strays off the roadway and flips over or hits a fixed object on the roadside. The driver is usually alone in the vehicle and makes no effort to avoid the crash. The National Highway Traffic Safety Administration estimates that rumble strips could cut the rate of ROR crashes in half. Evaluation studies undertaken to date by several States have documented reductions in ROR crashes of 20 to 70 percent.
Rumble strips improve highway safety in other ways as well.
For example, when installed in travel lanes, they can be used to alert motorists to changing traffic conditions, such as the need to slow down for an upcoming toll plaza or a signal light at an intersection. The site provides information on safety, noise, and vibration issues, as well as cost- benefit figures. It serves as a forum for the highway community to share information and resolve technical issues. It also includes case studies from States that have tried and evaluated shoulder rumble strips. According to Jim Growney of the FHWA New York Division, more than 60 requests for information have already been filled.