Antilock brakes and risk of front and rear impact in two-vehicle crashes.

While antilock brakes (ABS) have been convincingly demonstrated to enhance test track braking performance, their effect on crash risk in actual driving has been less clear. This research was conducted to seek clear associations between ABS and risk of involvement in one particular class of crashes, namely, two-vehicle crashes, particularly on wet roads. Police reported crashes in which a following vehicle strikes the rear of a lead vehicle are extracted from 1992 and 1993 calendar-year data for five states. The study uses seven General Motors passenger vehicles having ABS as standard equipment for 1992 models but not available for 1991. It is found that when driving on wet roads ABS reduces the risk of a vehicle crashing into a lead vehicle compared to its risk of being struck in the rear by (48 +/- 6)% (the error limits are one standard error). This large effect could arise from reduced risk of front impacts or increased risk of rear impacts. Using the assumption that side-impact crashes estimate exposure showed that, for wet roads, ABS reduces the risk of crashing into a lead vehicle by (32 +/- 8)%, but increases the risk of being struck in the rear by (30 +/- 14)%.