Green traffic light

How to read it

The MUTCD says traffic facing a steady circular green may go straight, turn right or left, or make a U-turn, unless signs, lane markings or separate turn signals limit it. It still yields to pedestrians lawfully in the crosswalk and to vehicles lawfully in the intersection, and a driver turning left also yields to oncoming traffic close enough to be an immediate hazard. A left turn on a green light without an arrow is what the MUTCD calls permissive: allowed, after yielding. A turn on a green arrow is protected. Pedestrians facing a green light, with no pedestrian signal, may cross within the crosswalk. This page describes the national standard and isn’t legal advice; the rules at a signal are set by state law and vary from state to state.

Also searched as: green light, steady green light.

Turning left on a green light

A left turn on a green light gets no priority over oncoming traffic under the MUTCD, and engineers have long worried that drivers read it otherwise. In 2006 the FHWA wrote that for many years some engineers had been concerned that drivers turning left on a permissive circular green might mistake it as giving them the right of way over opposing traffic. NCHRP Report 493 (2003) found the same in testing: drivers were confused by the circular green and often assumed it gave them the right of way during the permissive turn. That research led to the flashing yellow arrow, which a separate left-turn signal may show for the permissive turn in place of the green. Oregon’s manual says left turns on green must first yield to pedestrians and oncoming traffic, and Florida’s says the same.

How the state manuals word it

California’s handbook says a green light means GO, but that drivers should still stop for any vehicle, bicyclist or pedestrian in the intersection and not enter it if they cannot get completely across before the light turns red. Michigan’s says green means proceed with caution after checking for pedestrians and vehicles. Florida’s says go, but only if the intersection is clear.

No flashing green

The MUTCD gives a flashing green no meaning and does not allow one. It also forbids a flashing green, or a countdown for drivers, used as a warning that the yellow is coming, because research found such displays increase crashes. A steady yellow follows every circular green, except when a green arrow follows it directly.