Blue-green lights may become the standard for self-driving cars

Federal regulators have moved to settle a long-standing debate about how driverless vehicles should communicate their status to the outside world. The National Highway Traffic Safety Administration has released a proposal that designates cyan-colored lights as the standard signal for when an automated driving system is in control. This development marks a shift from years of industry speculation regarding flashing text, audio alerts, and other custom visual cues. The agency aims to provide a uniform way for robotaxis to indicate that no human is at the wheel.

The core of the proposal involves rewriting Federal Motor Vehicle Safety Standard No. 108. NHTSA argues that cyan fills a visual gap in the current traffic landscape. Existing automotive lighting relies heavily on red for braking, amber for turning, white for headlights, and blue or red flashing lights for emergency vehicles. By introducing a distinct blue-green hue, the agency believes it can avoid confusion among law enforcement and other road users. The goal is to ensure that when a self-driving car is operating, its status is clear and consistent regardless of the manufacturer.

While the proposal establishes a national standard, it does not mandate that every vehicle adopt the lights. Cyan marker lamps would remain optional for automakers. However, if a company chooses to install them, the vehicle must adhere to specific federal rules regarding color, brightness, and location. This approach is intended to prevent a fragmented market where different robotaxi operators use varying signals. It allows companies like Waymo, Nuro, and Zoox, as well as automakers such as GM and Mercedes-Benz, to adopt a uniform setup if they wish.

There is some precedent for this specific color choice. Mercedes-Benz previously received state-level approval for turquoise lights on its Level 3 Drive Pilot vehicles. Although the automaker has since abandoned that specific plan in favor of a different system, the regulatory interest in turquoise and cyan tones remains. NHTSA seeks to codify this visual language at the federal level to create a coherent national framework for autonomous transport.

Beyond the new lighting rules, the agency is proposing to remove several requirements that may be obsolete for human-free designs. Current regulations demand physical hazard switches, manual beam shifters, and turn levers inside the cabin. NHTSA suggests eliminating these mandates to give engineers more flexibility. The agency is also updating testing standards for 12.8-volt systems to accommodate modern LED architectures. Additionally, it is considering removing rules that dictate whether high-beam lights must be positioned above or below low-beam lights.

These changes fit into a broader Department of Transportation strategy to streamline the deployment of autonomous vehicles. The administrative push aims to make it easier for manufacturers to build cars without traditional human-centric controls like steering wheels and pedals. By reducing regulatory friction, the government hopes to accelerate the integration of driverless technology into daily traffic.

Despite the push for modernization, regulators are still enforcing existing rules strictly. Last month, NHTSA launched an audit query into the Tesla Cybercab. The investigation examines the technical data Tesla used to certify the vehicle, specifically focusing on the absence of sideview mirrors, pedals, and a steering wheel. These features are currently required under the Federal Motor Vehicle Safety Standard, highlighting the ongoing tension between traditional regulations and emerging autonomous technology.