Federal Agency Proposes Cyan Lights for Driverless Cars

The long-standing debate over how self-driving vehicles should communicate their status to the public has reached a definitive turning point. Federal regulators have officially moved to settle the issue with a specific visual cue: a distinct blue-green light.

The National Highway Traffic Safety Administration released proposed changes to Federal Motor Vehicle Safety Standard No. 108 on Thursday. These revisions aim to rewrite existing rules to better accommodate autonomous vehicles. The proposal combines efforts to reduce regulatory barriers for human-free designs with a standardized method for robotaxis to communicate with the surrounding environment.

At the core of the proposal is the requirement for cyan-colored marker lamps. The agency argues this color will clearly and consistently signal to law enforcement and other road users when an automated driving system is operating the vehicle. The choice of cyan fills a visual gap in the current automotive lighting spectrum. Since red, amber, white, and flashing blue or red lights are already reserved for brakes, turn signals, headlights, and emergency vehicles, cyan offers a unique identifier without causing confusion among drivers.

There is some historical precedent for this type of lighting. Mercedes-Benz previously received state-level approval for turquoise lights on its Level 3 Drive Pilot cars. Although the automaker has since scrapped that specific idea in favor of a Level 2++ system, NHTSA views the move as a positive step toward a national standard. The agency hopes that robotaxi operators such as Waymo, Nuro, and Zoox, along with automakers like GM and Mercedes, can adopt this uniform approach.

Under the proposed rule, cyan marker lights would remain optional for manufacturers. However, by establishing official federal standards for the color, brightness, and location of these lights, NHTSA aims to ensure consistency. This prevents a confusing patchwork of different colors and signals from different brands. Instead, any automaker that chooses to add the feature would use a standardized and legal setup.

The proposal also targets outdated requirements that do not apply to vehicles without human drivers. Current rules demand physical hazard switches, manual beam shifters, and turn levers inside the cabin. The agency proposes removing these mandates to allow for cleaner interior designs. Additionally, NHTSA is updating the 12.8-volt testing standard to help automakers build around modern LED architectures without facing excessive administrative hurdles. The agency is also considering eliminating requirements that dictate whether high-beam lights must sit above or below low-beam lights.

This update is part of a broader push by the Department of Transportation to streamline the deployment of autonomous vehicles. The government aims to make it easier for automakers to build cars that lack traditional controls like steering wheels and pedals, which are designed for human operation. By clarifying the rules, regulators hope to accelerate the integration of these technologies into daily traffic.

Regulators are, however, still strictly enforcing existing rules as written. Last month, NHTSA opened an audit query into the Tesla Cybercab. The agency is examining the process and technical data Tesla relied upon when certifying the vehicle. The specific issue involves the absence of certain design features, including sideview mirrors, pedals, and a steering wheel, which are currently required under FMVSS.

The next steps for the proposal will involve a public comment period and further review by the agency. If finalized, the new standards will provide a clear legal framework for the next generation of driverless transportation. For readers in the Southwest, where robotaxi services are expanding, this could soon mean seeing a familiar blue-green glow on the road, signaling that the car is in the driver's seat.