Citation

Fambro D, Koppa R, Picha D, Fitzpatrick K. Transp. Res. Rec. 1998; 1628: 1-7.

Copyright

(Copyright © 1998, Transportation Research Board, National Research Council, National Academy of Sciences USA, Publisher SAGE Publishing)

DOI

10.3141/1628-01

PMID

unavailable

Abstract

One of the most important requirements in highway design is the provision of adequate stopping sight distance at every point along the roadway. At a minimum, this sight distance should be long enough to enable a vehicle traveling at or near the design speed to stop before reaching a stationary object in its path. Stopping sight distance is the sum of two components--brake reaction distance and braking distance. Brake reaction distance is based on the vehicle's speed and the driver's perception-brake reaction time (PBRT). Four separate, but coordinated, driver braking performance studies measured driver perception--brake response to several different stopping sight distance situations. The results from the driver braking performance studies suggest that the mean perception-brake response time to an unexpected object scenario under controlled and open road conditions is about 1.1 s. The 95th percentile perception-brake response times for these same conditions was 2.0 s. The findings from these studies are consistent with those in the literature: that is, most drivers are capable of responding to an unexpected hazard in the roadway in 2.0 s or less. Thus, the American Association of State Highway and Transportation Officials' perception-brake response time of 2.5 s encompasses most of the driving population and is an appropriate value for highway design.

Language: en