NHTSA proposes cyan marker lamps as standard signal for autonomous vehicles

Cyan lamps would mark when software is driving

The National Highway Traffic Safety Administration has proposed rewriting Federal Motor Vehicle Safety Standard No. 108, the rulebook covering vehicle lighting, so that autonomous vehicles can identify themselves with a distinctive blue-green marker lamp. According to The Verge, the amendment would allow cars running an automated driving system to display cyan marker lights that tell law enforcement and other road users that software, not a person, is at the wheel.

The color choice is deliberate. Red, amber, white and flashing blue-red combinations already carry fixed meanings for braking, turn signals, headlamps and emergency vehicles, so cyan is one of the few remaining hues that road users have not been conditioned to associate with something else.

Optional to install, standardized if installed

Under the draft rule the cyan lamps would not be mandatory, and manufacturers could skip them entirely. But NHTSA wants to define their color, brightness and mounting location at the federal level, so any company that does fit them ends up with the same legal, consistent configuration rather than a patchwork of competing colors and signals. The Verge reports the goal is to give robotaxi operators such as Waymo, Nuro and Zoox, together with automakers including GM and Mercedes, a single national standard to adopt.

There is precedent, if not staying power. Mercedes-Benz won state-level approval to run turquoise lights on its Level 3 Drive Pilot cars, though The Verge notes the company has since abandoned that approach in favor of a Level 2++ system.

Lighting rules rewritten for vehicles without drivers

The proposal also clears out requirements that presuppose a human operator. Current rules mandate physical hazard-warning switches, manual headlamp beam shifters and turn-signal levers inside the vehicle, all of which a driverless car has no use for; NHTSA would remove those mandates.

The agency would also update the 12.8-volt testing standard so automakers can certify modern LED lighting architectures without administrative workarounds, and it is weighing whether to drop the rule dictating whether high beams must sit above or below low beams.

The Verge frames the package as part of a wider Department of Transportation push to streamline autonomous vehicle deployment, including designs built without steering wheels or pedals intended for human control.

Enforcement continues while the rule is pending

Regulators are still applying the standards as currently written. The Verge reports that last month NHTSA opened an audit query into the Tesla Cybercab to examine the process and technical data Tesla used to certify the vehicle. At issue is the absence of features such as sideview mirrors, pedals and a steering wheel, all of which remain required under FMVSS.

Why it matters

The proposal gives autonomous vehicle developers something they have lacked: a concrete federal specification for how a driverless car should announce itself. Companies have spent years debating approaches such as scrolling text, audio cues and bespoke light arrangements, risking a landscape where every fleet signals differently and nobody on the street knows what to trust. A standardized cyan lamp, even an optional one, creates a single visual language that pedestrians, cyclists and police could learn once and apply everywhere.

Just as significant, the removal of human-centric lighting controls shows FMVSS beginning to be written for vehicles without drivers, a prerequisite for certifying steering-wheel-free designs like the Cybercab under existing law. The rule is still a proposal rather than final regulation, but it marks one of the clearest signs yet that US vehicle safety standards are being reshaped around automated driving.