NHTSA Draft Rule: Cyan Lights for Driverless Cars

The National Highway Traffic Safety Administration released a proposed amendment to Federal Motor Vehicle Safety Standard No. 108 on October 23. The draft rule introduces a mandatory color specification for external lighting on autonomous vehicles. The agency selected cyan, a blue-green hue, to distinguish cars without human drivers from conventional traffic.

NHTSA stated that cyan marker lamps would clearly signal to law enforcement and other road users when an automated driving system is active. The color choice addresses a gap in current visual signals. Existing standards reserve red for braking, amber for turn signals, white for headlights, and flashing blue or red for emergency vehicles. Cyan allows autonomous systems to operate without conflicting with these established color codes.

The proposal makes the cyan lights optional for manufacturers but sets federal requirements for their color, brightness, and placement. This approach aims to prevent a patchwork of different signals from emerging in the market. The standard would apply to companies operating robotaxis and autonomous shuttles, including Waymo, Nuro, Zoox, GM, and Mercedes. Mercedes previously received state-level approval for turquoise lights on its Level 3 Drive Pilot vehicles, though the automaker later shifted to a Level 2++ system.

The rule also removes internal lighting controls that are unnecessary in vehicles without human drivers. Current regulations require physical hazard switches, manual beam shifters, and turn levers. NHTSA proposes to eliminate these requirements. The agency also plans to update the 12.8-volt testing standard to accommodate modern LED systems. It is considering removing rules that dictate the relative height of high-beam and low-beam lights.

The changes align with a Department of Transportation initiative to accelerate the deployment of autonomous vehicles. The goal is to simplify the design of cars that lack steering wheels and pedals. While regulators are drafting new standards, they continue to enforce existing rules as written. NHTSA opened an audit query into the Tesla Cybercab last month. The review examines the technical data Tesla used to certify the vehicle. The agency is concerned about the absence of sideview mirrors, pedals, and a steering wheel, all of which are required under current federal standards.