Center high-mounted stop lamps (chmsl) have been standard equipment on passenger cars in the united states since september 1, 1985. This study investigated the potential benefit of extending the chmslto heavier vehicles by measuring the savings in brake reaction time. In an experimental field study of over 1000 trials, chmsls were installed on a pickup truck, a full truck, a cargo van, and a minivan.The brake reaction times of drivers following these vehicles with and without chmsls were measured. Activation of the chmsl in tandem with the standard brake lights had a small but statistically significant effect on the brake response time of the drivers in following vehicles. No statistically significant differences in chmsl effect were observed among the 4 test vehicles. This effect was similar in magnitude to the effect of a chmsl in a passenger vehicle when measuredunder the same conditions
Abstract