NHTSA Proposes Standardized Cyan Lighting for Autonomous Vehicles

The National Highway Traffic Safety Administration has moved to establish a uniform visual signal for driverless vehicles, proposing that manufacturers install distinct cyan-colored marker lamps. This initiative aims to resolve a long-standing industry debate regarding how autonomous cars should communicate their operational status to pedestrians, law enforcement, and other motorists on the road.

The agency’s proposal involves rewriting Federal Motor Vehicle Safety Standard No. 108 to specifically accommodate the unique requirements of autonomous driving systems. By defining a national standard for this blue-green light, NHTSA seeks to ensure that any vehicle operating without a human driver can be identified consistently across the country, regardless of the manufacturer or service provider.

The choice of cyan is driven by the need to fill a visual gap in the current automotive lighting palette. Existing regulations already allocate red, amber, white, and flashing blue or red lights for standard functions such as braking, turn signals, headlights, and emergency services. Regulators determined that a blue-green hue would theoretically allow autonomous vehicles to stand out without causing confusion among road users who are accustomed to the existing color codes.

While the lighting rule is a primary focus, the proposal also includes significant administrative updates to remove outdated requirements that do not apply to vehicles without human drivers. NHTSA plans to eliminate mandates for physical interior controls, such as manual beam shifters, physical hazard switches, and turn levers, which are often absent in fully autonomous designs.

Additionally, the agency is updating the 12.8-volt testing standard to better align with modern LED architectures, reducing administrative hurdles for automakers. The proposal also considers removing specific rules regarding the vertical positioning of high-beam and low-beam lights, offering manufacturers more design flexibility while maintaining safety standards.

This regulatory update is part of a broader Department of Transportation effort to streamline the deployment of autonomous vehicles. By creating a clear framework for lighting and removing obsolete control requirements, the government hopes to make it easier for companies to build and certify vehicles that lack traditional human-operated interfaces like steering wheels and pedals.

The proposed cyan marker lights would be optional for manufacturers under the new rules. However, by establishing official federal standards for the color, brightness, and placement of these lamps, NHTSA intends to prevent a fragmented market where different companies use varying colors or signals. This standardization is particularly relevant for major robotaxi operators such as Waymo, Nuro, and Zoox, as well as automakers including GM and Mercedes-Benz.

There is some prior precedent for this type of signaling, as Mercedes-Benz previously received state-level approval for turquoise lights on its Level 3 Drive Pilot vehicles. Although the automaker has since moved away from that specific system in favor of a Level 2++ configuration, the federal proposal aims to create a broader, uniform national standard that the entire industry can adopt.

Despite these efforts to simplify regulations for future vehicle designs, regulators continue to enforce current rules strictly for existing certifications. Last month, NHTSA initiated an audit query into the Tesla Cybercab to review the technical data and processes Tesla relied upon during its certification. This review focuses on the absence of certain design features, such as sideview mirrors, pedals, and a steering wheel, which are currently required under existing Federal Motor Vehicle Safety Standards.