The National Highway Traffic Safety Administration wants driverless cars to announce themselves with a specific color: cyan, a blue-green.
The agency released proposed changes to Federal Motor Vehicle Safety Standard (FMVSS) No. 108, the federal rule that governs vehicle lighting, rewriting it to fit autonomous vehicles. The proposal does two things. It cuts red tape for designs with no human driver, and it standardizes how robotaxis communicate with the people around them. Cyan-colored marker lamps are the first piece. The agency said the lamps are meant to signal clearly and consistently to law enforcement, and the broader aim is a common way for these vehicles to say no one is at the wheel.
That ends a long-running argument. Companies and regulators have floated flashing text, audio alerts and custom lights, and each approach would have left a pedestrian or police officer decoding a different signal on every brand of car. A single federal color replaces that guesswork with a rule.
Cyan is also a sensible pick on its face. Road vehicles already use white, red and amber for headlights, brake lights and turn signals, and emergency vehicles lean on red and blue. A blue-green lamp sits apart from all of those, though how distinct it looks in daylight, rain or fog is a question the rulemaking will have to answer.
The other half of the proposal may matter as much to manufacturers. FMVSS 108 was written around cars with drivers, so rewriting it to remove requirements that assume one is a precondition for building vehicles with no human-operated controls. This is a proposal, not a final rule, and the lighting details can still change before it takes effect.