On October 26, the National Highway Traffic Safety Administration proposed a new kind of exterior light for vehicles controlled entirely by an automated driving system. The lamp would be cyan, a blue-green color that does not already carry the familiar traffic meanings of red, amber, or white.
The proposal would not put the light on every automated vehicle. Manufacturers could choose whether to install it. If they did, the lamps would have to follow federal rules for color, brightness, placement, visibility and activation. At least one would be visible from the front, rear and each side. The light would stay steady rather than flash.
For someone standing at a crosswalk or riding beside the car, the proposed meaning is limited: the automated driving system is in full control, and no occupant is expected to be watching the road. That separates full automation from driver-assistance features that still leave a person responsible for driving.
The light would identify the vehicle's control state. It would not tell you that the vehicle has detected you, plans to yield or is about to turn. NHTSA says it is not aware of research supporting the use of this lamp to signal a vehicle's intended movement.
That gap matters because people learn road signals through repeated use. A turn signal announces a planned direction. Brake lights show that a vehicle is slowing. A new cyan lamp would arrive without that long public history. NHTSA cited an international survey in which most respondents supported marker lamps, but support for the idea does not show that people will understand the signal correctly or become safer around it.
The agency says it does not yet have enough information to require these lamps on every automated vehicle. The rule remains a proposal, and public comments are due November 25.
If a cyan marker begins appearing on local streets, use it as a status light and keep watching the vehicle's speed, path, turn signals and brake lights. The useful question is simple: What does this light actually tell me, and what am I adding to it?