Self-Driving Trucks May Replace Warning Triangles With Cab-Mounted Beacons
FMCSA to Allow Self-Driving Trucks to Use Cab-Mounted Warning Beacons in Place of Triangles
The Federal Motor Carrier Safety Administration is granting a limited five-year exemption allowing certain autonomous trucks to use cab-mounted warning beacons instead of traditional roadside warning devices such as reflective triangles or fusees.
The exemption applies to Aurora Operations Inc. and other motor carriers operating commercial motor vehicles equipped with Level 4 automated driving systems. Other carriers may operate under the exemption only after providing written notice to FMCSA and meeting the agency’s reporting and operating requirements.
FMCSA announced the decision Oct. 8. The exemption is scheduled to remain in effect through Oct. 7, 2031.
How the exemption changes current requirements
Federal regulations generally require a truck stopped on a roadway or shoulder to activate its hazard warning lights and place warning devices around the vehicle within 10 minutes. The required devices typically include three bidirectional reflective triangles or at least six fusees, positioned in front of and behind the stopped vehicle as specified by the regulations.
Those requirements are intended to alert approaching motorists to a disabled or stopped commercial vehicle. They also require a person to leave the cab, walk along the roadway or shoulder and place the devices in the required locations.
Under the new exemption, qualifying carriers may use cab-mounted warning beacons in place of the warning devices specified in federal regulations. FMCSA is granting relief from the warning-device placement requirements in 49 CFR 392.22(b), the steady-burning lamp requirements in 49 CFR 393.25(e), and the requirements governing the types and number of warning devices in 49 CFR 393.95(f).
The exemption does not apply automatically to every automated truck. Carriers other than Aurora must notify FMCSA in writing before beginning operations covered by the exemption and must comply with additional conditions intended to give the agency oversight of the program.
Reporting and operating restrictions
Participating carriers must submit annual reports covering beacon malfunctions, power issues and other instances in which the equipment did not operate as required. FMCSA said the reporting requirement is intended to help the agency monitor the technology during the exemption period.
The exemption also bars certain higher-risk operations. It does not cover operations that would otherwise require an “H,” “X,” “P” or “S” commercial driver’s license endorsement if a human driver were operating the vehicle. The exemption specifically prohibits the transportation of passengers and hazardous materials.
FMCSA said those limits distinguish the current exemption from Aurora’s earlier request for broader relief. The company initially sought an exemption from the warning-device placement rules in 2023. In December 2024, the agency denied a request that would have applied more broadly to unspecified carriers, equipment and vehicles without the same notification and monitoring controls.
Aurora later received a temporary, narrow waiver while the issue was reconsidered. The company also filed a legal challenge after its original request was denied. The lawsuit was dismissed after FMCSA granted the temporary exemption.
FMCSA cites operational data
In approving the five-year exemption, FMCSA said it believed the arrangement would provide an equivalent or greater level of safety than continued compliance with the existing warning-device rules for the covered vehicles.
The agency cited data submitted by Aurora from operations conducted under the waiver between Oct. 10, 2025, and Jan. 9, 2026. During that period, 34 commercial vehicles traveled more than 500,000 miles. According to FMCSA, the beacons operated as expected without reported faults, malfunctions or power issues.
The agency also cited a potential safety benefit for conventional truck operations. A cab-mounted beacon would eliminate the need for a driver to exit the cab, walk alongside an active highway or shoulder and manually place warning devices near a disabled vehicle.
FMCSA noted that removing that exposure could benefit human drivers as well as autonomous vehicles. The agency said updating the underlying warning-device requirements for all commercial motor vehicles, rather than only Level 4 automated vehicles, “may be ripe for future regulatory action.”
Industry response remains divided
FMCSA received 402 public comments on Aurora’s request. Supporters backed the use of warning beacons for vehicles that do not have a driver available to deploy roadside devices. Opponents questioned whether a beacon mounted on the cab can provide the same warning in every situation, including on curves, hills, in poor weather and with different trailer configurations.
The Owner-Operator Independent Drivers Association opposed the exemption. OOIDA President and CEO Todd Spencer said the organization considers reflective warning devices a proven safety measure and argued that beacons may not provide an adequate replacement across the range of roadside emergencies and equipment failures encountered by truck drivers.
The exemption is limited to Level 4 automated driving system-equipped commercial vehicles and includes advance notice, annual reporting and operational restrictions. For professional drivers, the decision also signals that FMCSA is examining whether the traditional process of leaving a truck to place warning devices remains the best approach for every type of commercial vehicle.
