Safety Evaluation of Rolled-In Continuous Shoulder Rumble Strips Installed on Freeways. Summary Report

摘要

The 1997 statistics from the fatality analysis reporting system (FARS) show that 37,280 fatal crashes occurred, with 11,126 of these crashes being coded as single-vehicle run-off-the-road crashes.(1) This significant safety problem is being addressed with continuous shoulder rumble strips (CSRS) and other safety treatments by many highway agencies. CSRS operate as a countermeasure to a class of crashes related to driver inattention. Driver inattention comes in many forms, including distraction, daydreaming/competing thoughts, fatigue/drowsiness, and alcohol/drug impairment. CSRS are continuous bands of raised material or indentations formed or grooved in the shoulders to alert drivers starting to drift off the road. They alert drivers by transmitting sound and vibration through a vehicle. The warnings provided by CSRS give notice to drivers to take corrective action before they run off the roadway. This study conducted before/after safety evaluations of projects involving the installation of rolled-in CSRS on rural and urban freeways. During resurfacing and shoulder rehabilitation projects, rolled-in CSRS are formed by a roller that leaves grooves during the compaction of the asphalt on the shoulder. In recent years, most CSRS installations have been of the milled type. Field tests conducted by Virginia Department of Transportation(2) for pavement roughness and sound levels on various typical rumble strips found that the milled type was 12.6 times and 3.35 times greater in the pavement roughness index and sound levels, respectively, than the rolled type.