The Color Cyan Is Set to Become the National Language of Driverless Cars

For years, the automotive industry has struggled to define how a car without a driver should announce its presence to the world. Manufacturers have debated everything from flashing text displays to audio alerts, but no consensus emerged. That uncertainty is now ending, as federal regulators have stepped in to mandate a single, distinct visual signal: a cyan-colored light. This move seeks to bring order to the growing fleet of autonomous vehicles that are increasingly sharing the road with human-driven traffic.

The National Highway Traffic Safety Administration has released proposed changes to Federal Motor Vehicle Safety Standard Number 108. The rewrite specifically targets the needs of autonomous vehicles, aiming to both reduce bureaucratic hurdles for human-free designs and standardize how these cars communicate with their surroundings. The core of this proposal involves cyan marker lamps designed to clearly signal to law enforcement and other road users that an automated driving system is in control. The choice of blue-green is strategic, as it fills a visual gap in the existing spectrum of vehicle lights.

Currently, the road is crowded with red, amber, white, and flashing blue or red lights used for brakes, turn signals, headlights, and emergency services. Cyan offers a unique hue that can theoretically be recognized without causing confusion for drivers who are accustomed to traditional lighting cues. This approach builds on existing precedent, such as the state-level approval granted to Mercedes-Benz for turquoise lights on its Level 3 Drive Pilot vehicles. Although Mercedes has since shifted its strategy toward a Level 2++ system, the federal agency aims to establish a uniform national standard for operators like Waymo, Nuro, and Zoox, as well as manufacturers like GM.

Under the new rules, the installation of cyan marker lights would remain optional for manufacturers. However, by defining specific federal standards for the color, brightness, and placement of these lights, the agency intends to prevent a chaotic mix of varying signals. This ensures that any automaker choosing to adopt the feature uses a consistent and legal configuration. The proposal also seeks to eliminate lighting requirements that are irrelevant to vehicles without human drivers, such as the need for physical hazard switches, manual beam shifters, and internal turn levers.

The agency is also updating the 12.8-volt testing standard to accommodate modern LED architectures, allowing automakers to build vehicles without navigating excessive administrative processes. Additionally, NHTSA is considering removing requirements that dictate the vertical positioning of high-beam lights relative to low-beams. These changes are part of a broader Department of Transportation effort to streamline the deployment of autonomous vehicles by making it easier for manufacturers to design cars without traditional controls like steering wheels and pedals.

Despite these moves to simplify regulations, the enforcement of current rules remains strict. Last month, NHTSA launched an audit query into the Tesla Cybercab to examine the technical data and certification processes used by the company. The investigation focuses on the vehicle's lack of certain design features, including sideview mirrors, pedals, and a steering wheel, which are currently mandated under existing federal safety standards. This tension highlights the ongoing balance between modernizing regulations for autonomous technology and maintaining the current legal framework.