NHTSA proposes cyan lights for robotaxis, following Mercedes/China

The National Highway Traffic Safety Administration, or NHTSA, is proposing cyan lamps as a standardized signal for autonomous vehicle operation. The lights would tell people outside the vehicle that its driving system, rather than an actively driving human, is controlling the car. This matters because autonomous vehicles are beginning to spread on US roads, but no standard visual message currently identifies them.

The proposal would allow automakers to add cyan lights around a vehicle’s exterior. They would activate when the vehicle operates autonomously and deactivate when it returns to human driving. Mercedes first proposed the idea with its DRIVE PILOT level 3 system, which was trialed in California for two years.

The draft regulation would make the lights optional, not mandatory. Even so, NHTSA expects the proposal to encourage automakers to plan for a future in which cyan lighting could become a required, nationwide signal for autonomous operation.

The proposed rule ties the cyan lights directly to the vehicle’s operating mode. They should turn on when the car is operating autonomously, giving people outside it a clear signal that the automated system is driving. They should turn off when autonomous operation ends and a human resumes active control.

The lights must not remain on during ordinary driver-controlled travel. NHTSA also proposes that all the cyan lamps switch on and off simultaneously. That coordinated behavior would make the message easier to understand from outside the vehicle, rather than leaving observers to interpret separate or inconsistent lights.

The draft regulation does not require automakers to install the lights. It would allow their optional inclusion, while establishing how they should function if used. The article suggests automakers may still adopt them early as autonomous vehicles become more common and future requirements become possible.

NHTSA’s proposal is designed to make the autonomous-operation signal visible to people approaching the vehicle from any direction. That matters on roads, at intersections, and during emergency responses, where an observer may see only the vehicle’s front, side, or rear. A signal visible from one angle would not be reliable enough.

The proposed arrangement places cyan markers on the vehicle’s front, sides, and rear. These markers must all be at least 15 inches off the ground. The regulation also says the lights should turn on and off together, so the vehicle presents one consistent signal rather than a confusing mixture of illuminated and dark lamps.

The lights would remain optional under the draft. Still, the detailed placement and visibility requirements give automakers a common design target. The article says LEDs cost very little, so manufacturers may begin incorporating the system even before it becomes mandatory.

Police officers and emergency responders may encounter a vehicle with nobody in the driver’s seat. Without a clear signal, they might not know whether the driver is missing, needs rescue, or was never expected to control the car. They also need to recognize when the vehicle is operating autonomously so they can respond appropriately during an emergency.

Cyan exterior lights would provide that information before responders approach the vehicle. The lights would identify autonomous operation from outside, including when viewed from the front, sides, or rear. This is especially important because the article notes that no standardized message currently tells observers that a vehicle is driving itself.

The proposal would make cyan lights optional, but it creates a common visual language for autonomous vehicles. As these vehicles spread across US roads, a standardized signal could reduce confusion during police stops, emergency scenes, and other situations involving responders.

The key difference is responsibility. Mercedes’ DRIVE PILOT is described as a level 3 driver-assist system. Under certain conditions, it lets the driver go hands-free and allows the car to truly drive itself. The driver is not responsible for the vehicle during those approved operating periods.

Tesla’s Full Self-Driving, by contrast, is described in the article as a level 2 system. Even when the system is switched on, the driver remains responsible for driving. The label “Full Self-Driving” therefore does not mean the same thing as the level 3 operation described for Mercedes.

This distinction helps explain why autonomous-operation lights matter. A level 3 vehicle may have nobody actively driving from the seat, so police and emergency responders need an external signal. Mercedes proposed cyan lights alongside DRIVE PILOT, which NHTSA is now considering nationally, although installation would remain optional.

Mercedes and China are developing similar lights because autonomous vehicles are spreading, while no single visual message tells outsiders that a car is driving itself. A common signal could help police, emergency responders, and other road users recognize autonomous operation quickly. It could also prevent each automaker from creating a different system.

Mercedes proposed cyan exterior lights alongside its DRIVE PILOT level 3 system. The company trialed the system in California for two years, and NHTSA is now proposing cyan lights nationally. China released a similar draft standard, using turquoise, after the proliferation of autonomous-vehicle lights there. Its government asked automakers to stop doing their own thing.

Both proposals are optional at this stage. China’s draft would take effect in 2028, while NHTSA’s draft would allow cyan lights without requiring them. The article suggests broader requirements could come quickly as autonomous vehicles become more common.

Traditional vehicle-safety rules assume that a human sits behind a steering wheel and controls the car. Autonomous vehicles may operate differently, so some requirements no longer fit their design. NHTSA’s draft updates Federal Motor Vehicle Safety Standards to allow flexibility for operations that autonomous vehicles will not use.

For example, existing rules require a turn signal to switch off automatically after the steering wheel turns beyond a threshold and then returns to neutral. A vehicle without a steering wheel cannot follow that mechanism. The proposal would delete that requirement for autonomous cars and change certain headlight rules to provide more design flexibility.

The draft also addresses required driver displays and other rules built around human control. The article supports reasonable changes, but says loosened requirements should be watched carefully. The broader aim is to adapt safety standards without forcing autonomous vehicles to retain equipment or behaviors they do not need.