NHTSA Technical Report Number DOT HS 808 696March 1998

The Long-Term Effectiveness of Center High Mounted Stop Lamps in Passenger Cars and Light Trucks

Charles J. Kahane, Ph.D. and Ellen Hertz, Ph.D.


Center High Mounted Stop Lamps (CHMSL) have been standard equipment on all new passenger cars sold in the United States since model year 1986 and all new light trucks since model year 1994, as required by Federal Motor Vehicle Safety Standard 108. The purpose of CHMSL is to safeguard a car or light truck from being struck in the rear by another vehicle. When brakes are applied, the CHMSL warns drivers of following vehicles that they must slow down. This report tracks the effectiveness of CHMSL, year by year, from 1986 through 1995. The statistical analyses are based on police-reported crash files from eight States. It was found that: