Regulators push for blue-green lights on driverless cars

The federal government has moved to end years of uncertainty regarding how driverless vehicles should communicate their status to the public. After a long period of debate over various signaling methods, including flashing text and audio alerts, regulators have settled on a specific visual cue. The National Highway Traffic Safety Administration, or NHTSA, is proposing that autonomous vehicles display a distinct blue-green light to indicate that no human is at the wheel. This move represents a decisive step in standardizing the visual language of the road for the emerging robotaxi industry.

The proposal involves rewriting parts of Federal Motor Vehicle Safety Standard No. 108 to better accommodate autonomous technology. The agency aims to reduce regulatory hurdles for designs that lack traditional human controls while establishing a uniform way for these vehicles to signal their operational mode. The core of the plan is the adoption of cyan-colored marker lamps. These lights are intended to provide a clear and consistent signal to law enforcement officers and other drivers when an automated driving system is in control.

The choice of cyan is driven by practical considerations in traffic safety. The automotive industry already utilizes red, amber, white, and flashing blue or red lights for standard functions such as braking, turn signals, headlights, and emergency services. By selecting a color that is not currently in common use for these purposes, regulators believe they can fill a visual gap without causing confusion among road users. This ensures that the signal for an autonomous vehicle is immediately distinguishable from other standard vehicle lighting.

There is existing precedent for this type of signaling. Mercedes-Benz previously received state-level approval for turquoise lights on its Level 3 Drive Pilot vehicles. Although the automaker later abandoned that specific approach in favor of a Level 2++ system, the concept of using non-standard colors for autonomous status has already been tested. NHTSA now seeks to create a national standard that operators such as Waymo, Nuro, and Zoox, along with manufacturers like GM and Mercedes, can adopt uniformly across the country.

Under the proposed rule, the installation of cyan marker lights would remain optional for manufacturers. However, the agency intends to define official standards for the color, brightness, and placement of these lights. This regulatory framework is designed to ensure that if an automaker chooses to include the feature, it does so with a consistent and legal setup. The goal is to avoid a fragmented market where different companies use varying colors and signal patterns, which could lead to driver uncertainty.

The regulatory update also seeks to remove requirements that are impractical for vehicles without human drivers. Current rules mandate the presence of physical hazard switches, manual beam shifters, and turn levers inside the vehicle cabin. NHTSA proposes to eliminate these mandates, recognizing that they do not apply to fully autonomous designs. Additionally, the agency plans to update the 12.8-volt testing standard to allow manufacturers to build around modern LED architectures without facing unnecessary administrative obstacles.

Further changes include a review of requirements regarding the positioning of high-beam and low-beam lights. NHTSA is considering removing the rule that dictates whether high beams must be situated above or below low beams. These adjustments are part of a broader administrative effort by the Department of Transportation to streamline the deployment of autonomous vehicles. The government aims to make it simpler for automakers to build cars that lack traditional controls like steering wheels and pedals, which are designed for human operation.

Despite these efforts to simplify regulations, regulators are still actively enforcing existing rules. Last month, NHTSA opened an audit query into the Tesla Cybercab. The investigation seeks to examine the process and technical data Tesla relied upon when certifying the vehicle and addressing related issues. A key point of contention is the absence of certain design features, such as sideview mirrors, pedals, and a steering wheel, which are currently required under FMVSS. This situation highlights the ongoing tension between new regulatory proposals and the enforcement of current standards.

For the business sector, these changes signal a shift toward a more standardized and predictable regulatory environment for autonomous technology. By defining specific lighting standards and removing outdated design mandates, the federal government is attempting to lower the barrier to entry for new vehicle architectures. This approach could accelerate the market for driverless cars by reducing the complexity of compliance for manufacturers and providing a clear visual identifier for consumers and other road users.