When A Traffic Signal Goes Dark
Traffic signals lose power for many reasons, but there's only one way to drive through an intersection when the signal goes dark. 

Treat it like a four-way stop.

Washington State law requires drivers to treat an intersection with a non-functioning traffic signal as an all (four)-way stop.  The following section from the Revised Code of Washington deals with intersections with non-functioning traffic signals:

RCW 46.61.183.  Non-functioning signal lights.  Except when directed to proceed by a flagger, police officer, or firefighter, the driver of a vehicle approaching an intersection controlled by a traffic signal that is temporarily without power on all approaches or is not displaying a green, red, or yellow indication to the approach the vehicle is on, shall consider the intersection to be an all-way stop.  After stopping, the driver shall yield the right-of-way, in accordance with RCW 46.6.181(1) and 46.61.185.

Here are the basic right-of-way rules for vehicles approaching all-way stops.  Keep in mind that the law says who must yield the right-of-way, it does not give anyone the right-of-way:

  • When two vehicles approach or enter an intersection from different roadways at approximately the same time, the driver of the vehicle on the left shall yield the right-of-way to the vehicle on the right.  In other words, when two vehicles stop together at the intersection, if there is a vehicle to your right, it goes first.
  • Drivers turning left must yield to oncoming vehicles going straight ahead.

Drivers must do everything possible to keep from striking a pedestrian or another vehicle, regardless of the circumstances.

So remember, basic right-of-way rules for all-way stops apply to signalized intersections without power.  And, unless a flagger, a police officer, or a firefighter directs you to do otherwise, you are required to stop and yield the right-of-way in accordance with the law.