Motor carriers to install pulsating brake lights

By: Daren Hansen

Publication: Transportation Regulatory Alert

Date Posted: 01/15/2021

For the first time, the FMCSA is allowing interstate motor carriers to install pulsating brake lights on their commercial trailers and straight trucks.

The regulations haven’t changed — they still prohibit pulsating brake lights — but the FMCSA has issued a five-year pass to allow such lights for now, potentially foreshadowing a rule change in years to come.

Five configurations for pulsating brake lights

The pulsating lights are allowed in one of five configurations.They can be added to any trailer or van-body straight truck, in addition to the normal steady-burning brake lamps. The only catch is that they must pulsate in an amber color for only four seconds before turning red and burning steadily until the brakes are deactivated.

The special exemption was issued on December 7 and will be in place through 2025 unless the lights are found to be dangerous. That’s not likely to happen, however. A long-term trial using tank trailers found a 34-percent reduction in rear-end collisions, so the added lights appear to be an effective option.

Tank trailers have been allowed to have flashing brake lights since October, and theirs can be amber or red. The FMCSA did not explain why tankers can have flashing red lights, but now says that research has found an advantage of amber over red in terms of grabbing drivers’ attention.

Rear-end crashes generally make up about 30 percent of all crashes, the FMCSA says, and large trucks are three times more likely than other vehicles to be struck in the rear in two-vehicle fatal crashes.


Key to remember: Motor carriers now have the option to install pulsating brake lights on all commercial trailers and van-body straight trucks, as a way to prevent rear-end collisions.

About the author
Daren Hansen - Transportation Safety Editor

Based on his expertise in the Federal Motor Carrier Safety Regulations, Daren is responsible for writing and editing content for safety-related products, publications, and services for the trucking industry,

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