We all tend to walk around our own cars several times each week without even taking a look at the little red lamp sitting above the rear windshield. It is simply another feature positioned near the boot and rear glass. However, a National Highway Traffic Safety Administration report tracking the device over several years found that this small lamp reduced rear-impact crashes.
The lamp is officially known in the United States as the Center High Mounted Stop Lamp, or CHMSL. It became standard equipment on all new passenger cars sold in the US from model year 1986 and on all new light trucks from model year 1994, under Federal Motor Vehicle Safety Standard 108. Its purpose is straightforward: when the brakes are applied, the centrally positioned lamp gives following drivers another brake signal, positioned higher than the conventional rear lamps.
