FMCSA grants Aurora five-year beacon exemption, reversing 2024 denial on scope, specificity and monitoring

FMCSA granted Aurora Operations a five-year exemption from warning-device placement rules, extending the same relief to other carriers running Level 4 automated driving system trucks that notify the agency in advance. The exemption took effect October 7, 2026 and runs to October 7, 2031. It lets covered carriers use cab-mounted beacons when stopped on a road or shoulder, instead of placing reflective triangles at prescribed distances. FMCSA published the decision in the Federal Register on October 9. Two years earlier, the agency denied a version of the same request. Reading the two notices together shows what the agency said it needed before it would change its answer.

Why FMCSA said no in December 2024

The 2024 denial covered a joint request from Aurora and Waymo. The application sought relief for the two companies and for “other similarly situated companies.” FMCSA found that scope to be a central problem. Industry-wide exemptions are not the norm. The application left the carrier class and the equipment unspecified, giving the agency too little to evaluate or monitor.

The description of the devices added to the problem. The application allowed “any configuration of similar effectiveness,” which FMCSA said was too broad to enable monitoring of exemption terms.

The evidence was also insufficient for the scope sought. The Waymo study involved 48 participants on a closed test track. In that study, 8 out of 10 respondents who compared devices selected warning triangles as the better signal for a stopped truck. Aurora’s road study tested beacons for roughly 64 minutes across eight scenarios. In five of those eight, the share of drivers who responded was lower with beacons than with triangles. Neither study established a baseline condition measuring driver reaction to a stopped truck with no warning device in place.

FMCSA also noted that neither study had shown an autonomous truck would activate its flashers and beacons on its own, or demonstrated the timing of that activation relative to what the regulations require.

What the 2026 application addressed

Aurora’s renewed request came with the specifications the 2024 application lacked. The beacons must be amber and meet the Class 1 photometric requirements of SAE J595. They must be mounted at least 100 inches off the road surface and no lower than the upper sideview mirror edge. Redundant power sources are required to prevent a single-point failure. Beacons must activate within five minutes of a stop. That is shorter than the ten-minute window the regulations allow for placing triangles.

Any carrier other than Aurora must email FMCSA before starting operations under the exemption. Operations are confined to each truck’s validated operational design domain. Carriers cannot carry hazardous materials or passengers. Longer combination vehicles are limited to doubles with two 28-foot trailers; triples are barred. Crashes must be reported within five calendar days. Annual reports on malfunctions and power issues are due by November 1 each year.

In its October 2026 Federal Register notice, FMCSA stated that those terms directly address what the 2024 denial identified. The 2024 application included no monitoring controls and said nothing about annual reports. The 2026 exemption requires both.

What the road data and studies showed

From October 10, 2025 to January 9, 2026, Aurora ran beacons on 34 trucks under a temporary FMCSA waiver. Aurora reports those trucks covered more than 500,000 miles and that the beacons were active for a total of nearly 10 hours. Aurora stated that, to the company’s knowledge, the beacons ran without fault or power failure. FMCSA’s notice states the waiver trucks were not involved in any roadway collision while stopped with the beacons on. Aurora submitted its term reports as confidential business information, so the public record holds an aggregate summary rather than stop-by-stop data.

For the two 2022 studies, FMCSA took a second look at the same reports both applications had submitted. The 2024 denial had focused on the share of drivers responding, which was lower for beacons in five of eight Aurora study scenarios. The 2026 notice focused on when drivers began their first evasive response. By that measure, the average distance was 135.71 meters for beacons and 133.24 meters for triangles across the Aurora study, with motorists responding at a greater distance in six of eight scenarios when beacons were present. The Virginia Tech Transportation Institute study, prepared for Waymo, found that nighttime beacon exposure produced earlier braking. That study also surveyed participants on which device was more noticeable: in daylight sessions, 78.26 percent chose the beacons; in nighttime sessions, 83.33 percent did.

The two notices are reading different measures from the same Aurora data. The 2024 count tracked the share who responded; the 2026 count tracked the distance at which they did. Neither measurement settles the other.

What the sources leave open

OOIDA argued the studies did not cover enough road and weather conditions to support a broad application. FMCSA answered that the operational design domain restriction confines trucks to the environments in which they have been validated. OOIDA also noted that Aurora had not reported where the beacons activated during the waiver period or under what road conditions.

Advocates for Highway and Auto Safety argued that ten hours of beacon operation during planned stops does not provide a sufficient basis for a five-year exemption, and that testing beacons during expected stops generates no data on their performance in an emergency. Advocates also asked FMCSA to make Aurora’s waiver term reports available for public review; the agency noted Aurora had submitted them as confidential business information.

The Truck Safety Coalition, Citizens for Reliable and Safe Highways, and Parents Against Tired Truckers filed a joint comment arguing that cab-mounted beacons depend on the cab being aligned with the trailer. In many emergencies, they wrote, a slight or severe jackknife leaves the cab at an angle and the beacons out of position.

In December 2025, FMCSA published a notice describing a planned closed-course study of warning devices with 256 participants. That notice said FMCSA had never conducted experimental research on the effect of warning devices, and that the results could provide baseline data for future exemption decisions. It cited the Aurora and Waymo application. OOIDA asked FMCSA to wait for that study before granting any exemption. The exemption went forward regardless.

FMCSA can revoke the exemption if a carrier breaks the terms or if the safety level drops below what it was before the exemption was granted. Continuation inconsistent with Title 49 would also trigger revocation. Annual reports are one place where a safety decline would show up.