The authors have designed three studies to investigate the influence of in-lane (transverse) rumble strips on the braking patterns of drivers when the rumble strips are used to warn drivers of an upcoming traffic control device. Prior to these studies, no empirical work existed that could provide accurate confirmation of the effects of rumble strips on braking patterns. Despite their extensive use, in-lane rumble strips are not listed in the Manual of Uniform Traffic Control Devices as an approved traffic control device.
This portion of the research involves the use of a simulator to study braking patterns among sleep-deprived drivers who encounter rumble strips upon approaching a stop sign. The 20 subjects were commercial drivers between the ages of 25 and 60 with at least three year's driving experience. Each participant drove the 60-mile test route four times. Driving performance was measured using a battery of tests, including an EyeCheck device, an acuity test, a contrast sensitivity test, a psycho-motor vigilance test and a code substitution test.
Results indicate that there was little difference in mean approach speeds to controlled intersections with or without rumble strips. However, the presence of rumble strips caused drivers to brake to a greater extent earlier in the approach. Although sleep deprivation affected the steering patterns of drivers, it did not seem to affect their braking patterns.