Regulators Propose Cyan Lights to Identify Driverless Cars

Federal regulators are moving to standardize a specific visual cue for autonomous vehicles: a blue-green light intended to signal that no human is operating the machine. This proposal marks the end of a prolonged debate regarding how driverless cars should communicate their status to the public.

The National Highway Traffic Safety Administration (NHTSA) has released proposed modifications to Federal Motor Vehicle Safety Standard (FMVSS) No. 108. The primary objective is to establish a uniform method for autonomous vehicles to indicate the presence of an automated driving system. To achieve this, the agency is proposing the use of cyan-colored marker lamps.

The choice of cyan is rooted in a desire to avoid visual conflicts. Regulators note that the automotive industry already utilizes red, amber, white, and flashing blue/red lights to designate specific functions such as braking, turning, headlights, and emergency status. A distinct blue-green color is intended to fill this visual gap, ensuring that road users and law enforcement are not confused by the vehicle’s signals.

There is existing precedent for this technology, though it has seen mixed adoption. Mercedes-Benz previously secured state-level approval for turquoise lights on its Level 3 Drive Pilot vehicles. However, the automaker has since discontinued that specific feature in favor of a Level 2++ system. Despite this, federal regulators are moving to create a national standard that would apply to robotaxi operators and automakers alike.

Under the proposed regulations, the installation of cyan marker lights would be optional for manufacturers. However, by establishing federal standards regarding the color, brightness, and location of such lights, the agency aims to ensure that any manufacturer choosing to utilize them adheres to a consistent and legal configuration, rather than creating a confusing array of signals.

The proposal also addresses legacy regulations that are irrelevant to vehicles without a human operator. Current rules mandate physical hazard switches, manual beam shifters, and turn levers inside the cabin. The agency is proposing to remove these requirements, while also updating the 12.8-volt testing standard to accommodate modern LED architectures. Additionally, regulators are considering eliminating requirements that dictate the placement of high-beam lights relative to low-beam lights.

This initiative is part of a broader effort by the Department of Transportation to streamline the deployment of autonomous vehicles. The administration intends to facilitate the creation of vehicles that lack traditional controls, such as steering wheels and pedals, which are typically required for human-operated cars.

Despite the push to simplify regulations, authorities continue to enforce current safety standards. Last month, NHTSA opened an audit query into the Tesla Cybercab to examine the process and technical data on which Tesla relied when certifying the vehicle. The inquiry focuses on the absence of certain design features, specifically sideview mirrors, pedals, and a steering wheel, all of which are currently mandated under FMVSS.