NHTSA Proposes Cyan Lights to Identify Autonomous Vehicles

The National Highway Traffic Safety Administration has proposed that driverless vehicles install distinct cyan-colored lights to signal their automated status to other road users. This regulatory move aims to resolve a long-standing debate over how self-driving cars should visually differentiate themselves from traditional vehicles, selecting a specific blue-green hue to fill a gap in existing automotive lighting standards.

The proposal, released today, involves rewriting Federal Motor Vehicle Safety Standard No. 108 to accommodate the unique design of autonomous vehicles. By establishing a national standard, the agency intends to create a uniform visual language for robotaxi operators and automakers. This approach replaces the current patchwork of local rules and manufacturer-specific solutions with a single, federally recognized signal.

For years, the industry has explored various methods to indicate that no human is at the wheel, including flashing text displays, audio alerts, and custom light configurations. The NHTSA’s decision to favor cyan lights is driven by the need for clarity. Existing automotive lighting already utilizes red, amber, white, and flashing blue or red signals for functions such as braking, turn indications, headlights, and emergency vehicle identification. Cyan offers a distinct visual option that should not be confused with these established signals.

The agency cited precedent for this color choice, noting that Mercedes-Benz previously received state-level approval for turquoise lights on its Level 3 Drive Pilot vehicles. Although the automaker later abandoned that specific plan in favor of a Level 2++ system, the NHTSA believes a national standard is necessary to ensure consistency. The goal is to allow companies like Waymo, Nuro, Zoox, GM, and Mercedes to adopt a uniform system rather than creating disparate designs that may confuse law enforcement and pedestrians.

Under the proposed rule, the installation of cyan marker lamps would remain optional for manufacturers. However, if automakers choose to include them, they would be required to adhere to specific federal standards regarding color, brightness, and placement. This framework is designed to prevent a confusing mix of signals and ensure that any vehicle displaying the light does so in a legally consistent manner. The primary intent is to clearly and consistently inform law enforcement and other drivers when an automated driving system is in control.

In addition to the new lighting standard, the NHTSA is proposing to remove several requirements that are irrelevant for vehicles without human drivers. Current rules mandate the presence of physical hazard switches, manual beam shifters, and turn levers inside the vehicle. The agency suggests eliminating these mandates, as they are designed for human operation. Furthermore, the proposal includes updates to the 12.8-volt testing standard to allow automakers to utilize modern LED architectures without facing excessive administrative hurdles. The agency is also considering removing restrictions on the vertical placement of high-beam lights relative to low-beam lights.

This regulatory update is part of a broader Department of Transportation initiative to streamline the deployment of autonomous vehicles. The administration seeks to make it easier for manufacturers to build cars that lack traditional controls, such as steering wheels and pedals, which are intended for human drivers. By simplifying these requirements, the government aims to accelerate the integration of driverless technology into the national fleet.

Despite these efforts to modernize regulations, the NHTSA is simultaneously enforcing current rules strictly. Last month, the agency opened an audit query into the Tesla Cybercab to examine the technical data and processes Tesla used when certifying the vehicle. The inquiry focuses on the absence of design features such as sideview mirrors, pedals, and steering wheels, all of which are currently required under existing FMVSS regulations. This dual approach highlights the tension between updating standards for future technology and holding current manufacturers accountable to existing laws.