Studies show that amber turn signals reduce accidents, yet most signal lamps on the rear ends of North American automobiles, trucks and trailers are red. Why? Because amber’s not legally required, and it’s simpler and cheaper to use red for all rear-facing lamps.
Tanker fleets are more likely to use amber turn signals than other operators. This trailer also has white backup lights.
“The regulation right now is such that you can use either amber or red,” said Brad Van Riper, chief technology officer at Truck-Lite. So most trailers use a pair of red lamps on each side of the rear sill rather than three lamps – two red and an amber.
The reg is Federal Motor Vehicle Safety Standard 108, which defines what auto and truck builders must use for lighting in all directions, and the performance of the lamps and lenses. It says “yellow” for amber.
Standard 108 requires the usual white headlamps, white parking or running lamps, and red tail and stop lamps.
Trucks over 80 inches wide must have red clearance lights at rear corners, yellow clearance lamps at front corners and midway along each side of long trailers, and three red identification lamps at the upper or lower center of the rear of a trailer or truck body.
In 1963, federal authoritiesmandated yellow front turn signals to make them stand out from bright-white headlights, but continued to allow red turn signals at the rear, perhaps because red tail and stop lamps are not as bright as headlamps. That’s still the case.
Most trailers have a pair of red lights on each end of the sill, like the Truck-Lite LEDs on this Wabash unit. The one closer to the middle is a tail-stop light and the one nearer the corner is a tail-turn signal. Note that the Innotec LED clearance light is also a turn signal.
The studies supporting amber rear turn signals involved autos, but findings could be applied to trucks, Van Riper and others believe. Yet the federal authorities that did a study about five years ago have not acted on it.
“In 2008, the National Highway Traffic Safety Administration, responsible for writing U.S. vehicle safety standards, released tentative findings that amber (‘yellow’) turn signals are up to 28% more effective at avoiding crashes than red ones,” wrote automotive author Daniel Stern on the website aCarPlace.com.
“Then, in 2009, they released preliminary findings that across all situations, including those in which turn signals don’t matter,vehicles with amber rear turn signals are 5.3% less likely to be hit from behind than otherwise-identical vehicles with red ones.
“That means amber turn signals were seen as being more effective at avoiding crashes than the center third brake light mandated in 1986, with a 4.3% crash avoidance,” he wrote.
Amber rear turn signals are mandated in Europe and much of Asia, but not in the U.S. Not in Canada, either; its lighting standard is also numbered 108 and uses most of the American 108.
Truck owners may use amber rear turn signals and a few do. Most of those are tanker fleets which usually are especially conscious of safety, Van Riper says.
Managers who specify amber signals on trailers usually order three 4.5-inch lights on each side of the rear sill, with a center turn signal flanked by a tail-stop lamp as the inner one and a tail-stop lamp acting also as a clearance light at the outer position.
Wabash National seldom sees any orders for amber turn signals from its customers, says its business development manager, Mark Ehrlich. Adding a third lamp on each side complicates things a bit because the sill and wiring have to be altered to accommodate it, but it’s not an expensive option, either – probably under $150.
Many trailers have a yellow combination clearance-turn signal lamp along the bottom-center on each side. Here a red light would not be permissible because that lamp faces the side. And of course, side-mounted turn signals on trucks and tractors are yellow.
Stern, the automotive writer, is perplexed that NHTSA doesn’t require amber rear turn signals.
“Amber is the right way to do it,” he insists. “Traffic moves and changes quickly. Every single day, fractions of a second make the difference between a crash and a miss.
"Clear, unambiguous vehicle signals convey their message without requiring any decoding by other drivers – it’s a red light? It’s a brake light. It’s amber? Turn signal.”
Maybe truck operators should see it that way. Stern’s article is at http://www.acarplace.com/cars/turn-signals/.