FMCSA reopens comments on Grote's radar-triggered pulsing amber warning lights through Nov. 19

Could flashing amber lights on the back of a tractor-trailer give approaching motorists enough warning to avoid a rear-end collision? The Federal Motor Carrier Safety Administration has reopened public comments on a system designed to do exactly that, according to The Trucker on Oct. 21. In a notice published in the Federal Register on Oct. 20, the agency outlined additional information from Grote Industries about its Rear-End Collision Warning system and said it is accepting comments on that supplemental information through Nov. 19, under docket number FMCSA-2026-0100 at Regulations.gov.

The system uses rear-facing radar to detect approaching vehicles and calculate the time remaining before a potential collision. When it detects a substantial collision risk, auxiliary amber warning lamps automatically start pulsing for up to four seconds. The radar can detect approaching vehicles at distances of approximately 200 meters — about one-tenth of a mile — and the system operates without driver intervention. Grote submitted its application in December 2025, requesting a five-year exemption from federal regulations that generally require exterior lighting devices on commercial vehicles to remain steadily illuminated rather than pulsing. If granted, the exemption would allow motor carriers to operate vehicles equipped with the system; it would not require anyone to install it.

The reopening follows a safety question. The agency first published the application in February 2026 and later extended the comment period after the Commercial Vehicle Safety Alliance requested additional time to review it. Among the concerns was whether motorists might confuse the warning signals with conventional brake lights: the original application described auxiliary lamps that could flash or strobe before transitioning to steady-burning red as long as a collision threat remained. Grote has since clarified that the collision-warning function uses pulsing amber lights only, and that the transition to steady-burning red belongs to a separate brake-activated auxiliary warning function. If a collision warning and a braking event happen at the same time, the brake-activated function takes priority.

Grote also clarified that the proposed exemption would apply to all commercial motor vehicles, and that on combination vehicles hauling multiple trailers, including doubles and triples, the system would be installed on the rearmost unit. The company already has federal authorization for a related brake-activated pulsating warning light system; this application seeks additional flexibility for radar-triggered warnings that can operate independently of brake application. The agency has not approved the request, and before deciding it must determine whether the technology would provide a level of safety equivalent to or greater than existing requirements. Comments must address the supplemental information specifically, rather than the whole application.