Trucker Discussion

Can the addition of a pulsing brake lamp on the back of a trailer prevent rear-end collisions? FMCSA seems to think so, if its exemptions are any indication.

I don’t think I’ve seen so much attention to rear trailer visibility since conspicuity tape became mandatory 20 years ago. This time, however, it’s not a controversial mandate, but optional additional rear trailer and body lighting that pulses when the brakes are activated.

Federal Motor Carrier Safety Regulations require all exterior lamps (both required lamps and any additional lamps) to be steady-burning, except for turn signal lamps, hazard warning signal lamps, school bus warning lamps, amber warning lamps or flashing warning lamps on tow trucks and CMVs transporting oversized loads, and warning lamps on emergency and service vehicles authorized by state or local authorities.

But Oklahoma-based tank truck carrier Groendyke Transport decided it would bend those rules to tackle the problem it faced from distracted drivers hitting them from behind. The idea of the flashing amber light came from the advance warning signals that precede some traffic signals at rural intersections. They are used to warn drivers the traffic signal is about to change. 

In road testing, drivers began pulling the specially equipped trailers almost immediately reported seeing changes in the behavior of people driving behind them. When the brake lights came on (and the strobe began blinking), car drivers began making lane changes sooner to get around the truck, the drivers said. The amber strobe was making people notice that the brake lights were on.

Groendyke tracked two groups of trucks for 90 million miles over 30 months, from January 2015 to July 2017. One group was fitted with the strobes, the other without. The data revealed that the flashing amber light that blinked when the drivers applied the brakes reduced rear-end collisions by almost 34%.

However, during the testing, the company received somewhere in the neighborhood of 40-50 violations for using the technically illegal additional brake light. So in April 2018, after gathering and correlating all the data collected over the course of the trials, Groendyke submitted a formal petition to the Federal Motor Carrier Safety Administration, which was granted about a year later in April of 2019.

Groendyke is a member of the National Tank Truck Carriers, which was supportive of its exemption application, and filed for an exemption that would allow all tank truck carriers to install similar warning lights. That exemption was granted last October, a limited five-year exemption to allow motor carriers operating tank trailers to install a red or amber brake-activated pulsating lamp in the upper center position or in an upper dual outboard position on the rear of the trailers.

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