Federal Regulators Propose Cyan Lighting Mandate for Driverless Vehicles

The National Highway Traffic Safety Administration (NHTSA) has released a proposed update to federal vehicle safety standards that would establish a uniform visual signal for autonomous vehicles. The agency recommends that driverless cars utilize cyan-colored marker lamps to indicate that an automated system, rather than a human, is in control. This move aims to resolve years of industry debate over how robotaxis should communicate their operational status to other road users and law enforcement.

The proposal targets Federal Motor Vehicle Safety Standard No. 108, rewriting regulations to accommodate vehicles without human drivers. By defining specific requirements for the color, brightness, and placement of these lights, the federal government seeks to create a consistent national standard. This standardization is intended to benefit major robotaxi operators such as Waymo, Nuro, and Zoox, as well as automakers like General Motors and Mercedes-Benz, allowing them to adopt a single, legally compliant setup across different markets.

The selection of cyan is strategic. The automotive industry currently reserves red, amber, and white lights for standard functions like braking and turn signals, while flashing blue and red lights are associated with emergency vehicles. Cyan fills a visual gap, offering a distinct hue that should not be mistaken for existing signals. There is some precedent for this approach; Mercedes-Benz previously received state-level approval for turquoise lights on its Level 3 Drive Pilot vehicles, although the company has since shifted its strategy toward a Level 2++ system.

Under the new rules, cyan marker lights would remain optional for manufacturers. However, if an automaker chooses to install them, the vehicle must adhere to the new federal specifications. This prevents a fragmented landscape where different companies use varying colors or intensities, which could confuse drivers and pedestrians. The goal is to ensure that when a robotaxi signals it is operating autonomously, the message is clear and universally understood.

In addition to introducing the new lighting requirement, NHTSA proposes removing several legacy mandates that are less relevant for autonomous designs. The current rules require physical hazard switches, manual beam shifters, and turn levers inside the cabin. The agency suggests eliminating these requirements to simplify vehicle architecture. Furthermore, the proposal updates the 12.8-volt testing standard to align with modern LED technologies, reducing administrative burdens for manufacturers building with current electronic systems.

The agency is also reconsidering rules regarding the placement of high-beam and low-beam lights relative to one another. These changes are part of a broader Department of Transportation initiative to streamline the deployment of autonomous vehicles. The overarching objective is to make it easier for manufacturers to design cars without traditional human controls, such as steering wheels and pedals, which are unnecessary for fully automated operation.

Despite these efforts to modernize regulations, regulators are still enforcing existing rules strictly. Last month, NHTSA initiated an audit query into the Tesla Cybercab. The review aims to examine the technical data and processes Tesla used to certify the vehicle. A key point of contention is the Cybercab’s lack of sideview mirrors, pedals, and a steering wheel, all of which are currently required under FMVSS. This enforcement action highlights the tension between the desire to innovate and the need to adhere to established safety frameworks.

For California residents, who are among the most likely to encounter autonomous vehicles on public roads, this development signals a push toward greater clarity and consistency. As the robotaxi industry expands, the standardization of signals like the proposed cyan light could help reduce uncertainty for human drivers sharing the road. The proposal now moves through the rulemaking process, where it may be refined before becoming official federal law.