NHTSA Draft Rule: Cyan Lights to Signal Driverless Cars

Drivers sharing the road with autonomous vehicles will soon have a standardized visual cue to distinguish robotaxis from human-driven cars. The National Highway Traffic Safety Administration released a proposal on Wednesday to establish cyan marker lamps as the official light for vehicles operating without a human driver. The agency stated the color was selected to fill a visual gap, as red, amber, white, and flashing blue or red lights are already assigned to functions like braking, turn signals, and emergency vehicles.

The proposal amends Federal Motor Vehicle Safety Standard No. 108. It seeks to reduce regulatory friction for manufacturers building cars without steering wheels or pedals. NHTSA aims to create a single national standard so that companies like Waymo, Nuro, and Zoox, along with automakers including GM and Mercedes, use consistent lighting configurations. This would replace the current patchwork of different colors and signals used by various fleets.

The cyan lights would remain optional for manufacturers. However, if a company chooses to install them, federal rules would dictate their specific color, brightness, and placement. This ensures that law enforcement and other road users can reliably identify when an automated driving system is in control. The agency noted that the lights would clearly and consistently signal this status to everyone nearby.

Mercedes-Benz previously received state-level approval for turquoise lights on its Level 3 Drive Pilot vehicles. The automaker later dropped that approach in favor of a Level 2++ system. NHTSA now wants to formalize a national standard that all autonomous vehicle operators can adopt. The move aligns with a wider Department of Transportation push to accelerate the deployment of driverless technology.

The rule also proposes removing lighting requirements that do not apply to vehicles without human drivers. Current regulations mandate physical hazard switches, manual beam shifters, and turn levers inside the cabin. NHTSA would scrap these requirements. The agency also plans to update the 12.8-volt testing standard to accommodate modern LED systems and is considering relaxing rules about the vertical placement of high-beam versus low-beam lights.

Existing rules remain in force until the new standard is finalized. Last month, NHTSA opened an audit query into the Tesla Cybercab. The agency is examining the technical data Tesla relied on when certifying the vehicle, specifically regarding the absence of sideview mirrors, pedals, and a steering wheel. These features are currently required under federal standards, creating a compliance challenge for early driverless designs.

The proposal is part of an effort to modernize safety standards for a new class of vehicles. By standardizing the visual signal, the agency hopes to reduce confusion for pedestrians and other drivers. The rulemaking process will now proceed through the standard public comment and finalization stages before the amendments take effect.