NHTSA Proposes Cyan Lighting: Federal Standard for Driverless Cars

Autonomous vehicle developers have long debated how to visually distinguish driverless cars from those with human operators at the wheel. The National Highway Traffic Safety Administration (NHTSA) has now proposed a specific solution: a distinctive cyan light.

The agency released proposed amendments to Federal Motor Vehicle Safety Standard No. 108. This revision targets autonomous vehicles with two primary goals. First, it aims to reduce regulatory burdens for designs that lack a human driver. Second, it seeks to standardize how robotaxis communicate their status to surrounding traffic. NHTSA states that these cyan marker lamps would clearly signal to law enforcement and other road users when an automated driving system is active.

The selection of cyan addresses a specific gap in current vehicle lighting. The auto industry already utilizes red, amber, white, and flashing blue or red lights for functions such as braking, turn signals, headlights, and emergency vehicles. By introducing a distinct blue-green hue, NHTSA hopes to avoid confusion on the road while providing a consistent visual cue for automated operation.

Some manufacturers have already experimented with non-traditional colors. Mercedes-Benz received state-level approval for turquoise lights on its Level 3 Drive Pilot vehicles, though the company later shifted focus to a Level 2++ system. NHTSA aims to create a national standard that companies like Waymo, Nuro, and Zoox, along with automakers such as GM and Mercedes, could adopt uniformly. Under the proposal, cyan lights would remain optional for manufacturers, but any company choosing to install them would follow federal requirements for color, brightness, and placement.

The proposal also removes interior lighting controls that are unnecessary in vehicles without human drivers. Current rules mandate physical hazard switches, manual beam shifters, and turn levers inside the cabin. NHTSA would eliminate these requirements. The agency would also update the 12.8-volt testing standard to accommodate modern LED systems and is considering relaxing rules on the vertical placement of high-beam and low-beam lights.

These changes align with a Department of Transportation push to accelerate the deployment of autonomous vehicles. The government intends to make it easier for automakers to build cars without traditional human controls such as steering wheels and pedals. However, existing rules remain in force until the new standards are finalized. Last month, NHTSA opened an audit query into the Tesla Cybercab to examine the technical data Tesla relied on for certification. The agency is specifically concerned about the absence of sideview mirrors, pedals, and a steering wheel, all of which are currently required under federal standards.