NHTSA proposes cyan lights as the universal signal for driverless cars

The debate over how to visually identify a car with no human behind the wheel has finally settled on a specific shade of blue-green.

The National Highway Traffic Safety Administration has released proposed updates to Federal Motor Vehicle Safety Standard No. 108. These changes aim to simplify regulations for autonomous vehicles while establishing a uniform way for them to communicate their status. The core of the proposal involves a distinctive cyan-colored marker lamp that activates when an automated driving system is in control. This light would serve as a clear cue for law enforcement and other road users that the vehicle is operating without a human driver.

The choice of cyan is driven by the need to fill a visual gap in current traffic signals. The automotive industry already relies on red, amber, white, and flashing blue or red lights for functions like braking, turn signals, and emergency responses. By introducing a distinct blue-green hue, regulators hope to avoid confusion among drivers who are already processing a complex array of colors on the road. This approach allows for a clear, consistent signal that does not overlap with existing traffic conventions.

There is already some industry interest in using similar technology for this purpose. Mercedes-Benz previously secured state-level approval for turquoise lights on its Level 3 Drive Pilot vehicles. Although the automaker has since moved toward a different system, its earlier work provides a precedent for the use of non-standard colors in autonomous driving. The federal proposal seeks to create a national standard that all manufacturers can adopt, ensuring that the technology is applied uniformly across the market rather than varying by brand.

Several major players are expected to be affected by these changes. Robotaxi operators such as Waymo, Nuro, and Zoox would benefit from a standardized signal. Additionally, traditional automakers including General Motors and Mercedes-Benz could integrate the new lighting into their future vehicle designs. The proposal makes these cyan marker lights optional for manufacturers. However, if a company chooses to include them, they must adhere to specific federal standards regarding color, brightness, and placement on the vehicle.

The agency is also proposing to remove several outdated requirements that do not apply to cars without human drivers. Current rules mandate physical hazard switches, manual beam shifters, and turn levers inside the cabin. Since these controls are unnecessary for autonomous operation, NHTSA plans to eliminate these mandates. The proposal also includes an update to the 12.8-volt testing standard to better accommodate modern LED lighting architectures. Furthermore, regulators are considering removing rules that dictate the physical positioning of high-beam lights relative to low-beam lights.

This regulatory shift is part of a broader effort by the Department of Transportation to streamline the deployment of autonomous vehicles. The goal is to make it easier for automakers to build cars that lack traditional human-centric controls such as steering wheels and pedals. By removing administrative barriers and updating safety standards, the government aims to facilitate the transition to driverless technology. This move reflects a recognition that the current rules were largely designed for an era of human-operated vehicles.

Despite the push for modernization, regulators are still closely monitoring compliance with existing rules. Just last month, NHTSA opened an audit query regarding the Tesla Cybercab. The investigation focuses on the technical data and processes Tesla used to certify the vehicle. Specifically, the agency is examining the absence of features like sideview mirrors, pedals, and a steering wheel, which are currently required under the Federal Motor Vehicle Safety Standards. This ongoing oversight highlights the tension between updating regulations for the future and enforcing the current rules in the meantime.