FMCSA Let Driverless Trucks Skip the Warning Triangles. The Exemption Reads Like a Hardware Spec.

In December 2024, FMCSA turned down a request to let driverless trucks use beacons instead of warning triangles. Its objection then was that the request would “exempt a class of unspecified carriers using unspecified equipment on unspecified vehicles” [1]. On October 7, the agency granted almost the same relief to almost the same class of carriers. The difference is that this time the equipment is specified, down to the inch.

That is the part worth reading if you build autonomy stacks or the hardware around them. The exemption is six pages in the Federal Register, and its terms and conditions function as a product requirement.

What FMCSA granted

The notice, FR Doc. 2026-20734 at 91 FR 64736, was published October 9 under Docket No. FMCSA-2026-0958 and signed by Administrator Derek D. Barrs [1]. It exempts carriers running Level 4 automated driving systems from three rules: 49 CFR 392.22(b), which makes a driver place warning devices around a stopped truck within ten minutes; 393.25(e), which requires steady-burning exterior lamps; and 393.95(f), which calls for three reflective triangles or at least six fusees [1]. In their place, carriers may use cab-mounted warning beacons [1].

Aurora Operations applied, and FMCSA published the application for comment on April 15 [2]. At that point Aurora said it had 109 Class 8 trucks and expected more than 200 Level 4 trucks by the end of 2026 [2]. FMCSA received 402 comments [1].

The exemption is not Aurora’s alone. Any motor carrier operating Level 4 trucks can use it after sending FMCSA written notice [1]. FreightWaves reports that Kodiak AI, Waabi and Stack AV had already opted in to the shorter waivers Aurora had been running under since October 2025 [3].

The case for the grant rests on two 2022 studies and one quarter of road data. Aurora told FMCSA that from October 10, 2025 through January 9, 2026, 34 of its trucks drove more than 500,000 miles with beacons, which were switched on for nearly 10 hours in total, with no faults and no collisions while stopped [1, 2]. In Aurora’s naturalistic study, drivers began evading at an average 135.71 meters from beacons versus 133.24 meters from triangles [1]. The Virginia Tech Transportation Institute study, done for Waymo, found equivalent detection by day and night, and 83.33 percent of nighttime participants said the beacons were easier to see [1].

The opposition, and FMCSA’s answer

The Owner-Operator Independent Drivers Association argued the two studies ignore varied weather, road and lighting conditions, and that FMCSA should wait for its own research on warning devices [1]. Advocates for Highway and Auto Safety said ten hours of beacon use during planned stops says nothing about emergencies, and asked to see Aurora’s waiver reports [1]. FMCSA declined: Aurora filed those as confidential business information [1]. Several commenters raised jackknifed trailers blocking cab-mounted lights [1]. One owner-operator alleged a coordinated comment campaign by people with undisclosed ties to Aurora; the notice records the claim and doesn’t address it [1].

The Trucker reports that OOIDA’s president, Todd Spencer, called beacons an inadequate replacement, while the Truckload Carriers Association welcomed the decision [4].

FMCSA’s most interesting move is an admission. It says it “lacks data showing that warning triangles significantly improve driver reaction time,” and calls it historically unresolved whether such devices improve safety at all [1]. In other words, the baseline the beacons had to match was never measured well. FMCSA even says updating the warning-device rules for all trucks, not just driverless ones, “may be ripe for future regulatory action” [1].

The spec, if you’re building to it

This part is opinion, though the numbers are FMCSA’s.

Treat section VI.C as a hardware requirement. At least one rearward-facing beacon on each side of the cab and one forward-facing on the front; every light at least 100 inches off the ground, at or above the top of the side mirrors and below the top of the cab; total width no more than 122 inches; amber; SAE J595 Class 1 photometrics; a flash rate different from the hazard flashers; redundant power so no single failure kills them [1]. If you sell sensor pods or cab hardware to AV fleets, that envelope now competes for the same real estate.

The five-minute clock is a software requirement. Beacons must come on “as soon as possible, but in any event within five minutes” of any stop where the triangle rule would apply, and stay on until the truck moves or is recovered [1]. Human drivers get ten minutes [1]. Your minimal-risk-condition logic has to know what counts as a “necessary traffic stop” and what doesn’t, and log it, because the annual report wants the date, location, road type and trailer configuration of every time the beacons didn’t behave [1].

Self-certification under perjury is the gate. There is no approval step for a new carrier. You email FMCSA your USDOT number and a statement that you comply, signed under 28 U.S.C. 1746 [1]. That’s light process, and one commenter called it a self-certification mechanism with no independent review [1]. I think it’s the right trade for a small operator, but it puts the compliance burden on whoever signs.

The ODD clause carries more weight than it looks. Operations are limited to roadways in the truck’s “validated Operational Design Domain” [1]. The exemption never says who validates it. FMCSA uses the phrase to answer the weather objection, so your ODD documentation is now doing regulatory work [1].

Read what you asked for against what you got. Aurora asked for triples and tankers [2]. FMCSA allowed tankers and doubles of two 28-foot trailers, and barred triples [1].

There’s a preemption line too: during the exemption, no state may enforce a conflicting law on interstate operations under it [1]. Back in August I wrote about NHTSA’s Zoox exemption, where the operating rules sat in Operational Authorizations NHTSA could rewrite. This one is at least published, with stated revocation grounds [1].

What I’m watching

• Who files notice. FreightWaves names three carriers that used the waivers [3]. FMCSA hasn’t said whether it will publish the list of notifications.
• November 1. Annual reports are due by November 1 of each year a carrier operates under the exemption [1]. The notice doesn’t say whether a carrier three weeks in owes one this year, or whether any of the data becomes public once carriers mark it confidential [1].
• FMCSA’s own warning-device study. OOIDA asked the agency to wait for it [1]. If that research says triangles work better than FMCSA now assumes, the five-minute clock and the beacon spec are the obvious things to revisit.