Three experiments with transverse pavement stripes and rumble bars : final report.

Speed change was selected as an acceptable indication of the effectiveness of three devices in alerting drivers to an impending danger or maneuvering requirement. Transverse plastic pavement stripes with gradually decreasing spacing and an ABS plastic rumble bar in conjunction with yellow painted stripes were tested. A third experiment used polyvinyl chloride rumble bars. Both kinds of rumble bars caused larger speed reductions than the colored stripes.