What color should rear turn signals be? Most of the world (and ECE regulations) have for many years said they must be amber, but red is still permitted by U.S. regulations. The U.S. National Highway Traffic Safety Administration has long taken the position that amber signals offer no safety benefit over red ones, and mandating amber would unduly restrict automakers’ styling freedom.
Last Autumn, as reported in Driving Vision News, NHTSA released tentative findings that amber rear turn signals are up to 28% more effective than red ones, depending on the type of crash. Data have been accumulating in favour of amber since at least the 1970s; Volkswagen’s 1977 study concluded amber signals are better, and twenty years later UMTRI determined that drivers react significantly faster and more accurately to the brake lamps of a leading vehicle if its signals are amber rather than red. The missing link as far as American regulators were concerned was evidence that amber signals actually increase safety in real traffic. Now NHTSA has released findings that vehicles with amber rear indicators are overall 5.3% less likely to be hit from behind than are otherwise-identical vehicles with red indicators. The report says the benefit compares to the enduring 4.3% crash avoidance benefit of the center 3rd brake light (CHMSL) mandated in the U.S.A. and Canada since 1986, and NHTSA has opened a public comment docket on the matter. So far, the response from the general public is enthusiastically in favour of amber.
DVN view: Just a few years ago, American insistence on provisions for red rear indicators undermined an international effort towards a global lighting installation standard. The present philosophical shift at NHTSA ought to be met with our strongest assent, for this finding stands to greatly improve and perhaps accelerate international harmonisation of automotive lighting regulations, and perhaps to serve as a foundation for increased American attention to international lighting and signalling practice.
It is of course hard to lose any design freedom, but the evidence is now much stronger that amber is the correct colour choice for rear indicators. The responsible reaction to this new finding is to acknowledge NHTSA’s efforts to look to international consensus for potential improvements in crash avoidance through lighting and signalling specification.