WASHINGTON — Could flashing amber lights on the back of a tractor-trailer give approaching motorists enough warning to avoid a rear-end collision?
Grote Industries is seeking federal approval for a radar-controlled warning system designed to do just that. However, questions about how the lights operate have prompted the Federal Motor Carrier Safety Administration (FMCSA) to reopen public comments on the company’s exemption request.
In a notice published in the Federal Register Oct. 20, FMCSA outlined additional information provided by Grote concerning its Rear-End Collision Warning (RCW) system. The agency is accepting comments on the supplemental information through Nov. 19.
How the technology works
Grote’s proposed system uses rear-facing radar to detect approaching vehicles and calculate the time remaining before a potential collision.
When the system 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), according to Grote.
The system operates without driver intervention and is intended to provide an additional warning to motorists that may be approaching a commercial motor vehicle from behind.
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 Grote’s RCW system.
Safety concerns prompt clarification
FMCSA initially published Grote’s application for public comment in February 2026. The agency subsequently extended the comment period after the Commercial Vehicle Safety Alliance (CVSA) requested additional time to review the proposal.
Among the concerns raised was whether motorists might confuse the system’s 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.
CVSA questioned whether the red indication could mislead following motorists into believing the truck was braking. Grote has since clarified that the RCW function uses pulsing amber lights only, noting that the transition to steady-burning red is associated with a separate brake-activated auxiliary warning function.
If a collision warning and braking event occur simultaneously, the brake-activated function takes priority.
Separate from existing exemption
Grote already has federal authorization for a related brake-activated pulsating warning light system. The current application seeks additional flexibility for radar-triggered warnings that can operate independently of brake application.
Grote also clarified that the proposed exemption would apply to all commercial motor vehicles. On combination vehicles hauling multiple trailers, including doubles and triples, the system would be installed on the rearmost unit.
FMCSA has not yet approved the requested exemption.
Before issuing a decision, the agency must determine whether the proposed technology would provide a level of safety equivalent to or greater than existing federal requirements.
The agency is accepting comments specifically addressing Grote’s supplemental information, rather than reopening the entire application for discussion.
Comments on the current exemption request may be submitted through Nov. 19 at Regulations.gov under docket number FMCSA-2026-0100.
Linda Garner-Bunch has been with The Trucker since 2020, picking up the reins as managing editor in 2022. Linda has nearly 40 years of experience in the publishing industry, covering topics from the trucking and automotive industry to employment, real estate, home decor, crafts, cooking, weddings, high school sports — you name it, she’s written about it. She is also an experienced photographer, designer and copy editor who has a heartfelt love for the trucking industry, from the driver’s seat to the C-suite.
