Traffic lights, signs, and "right-of-way" rules tell you when to go or stop at an intersection.
Red – A red signal light means STOP. You can make a right turn against a red light after you stop and yield to pedestrians, bicyclists, and vehicles that are close enough to be a hazard. Do not make the right turn until you can turn safely. Do not turn if there is a sign posted for NO TURN ON RED. On a one-way street, you may turn left into a one-way street where traffic moves left if there is no sign which prohibits the left turn.
Red arrow – A red arrow means STOP until the green signal or green arrow appears. A turn may not be made against a red arrow.
Flashing red – A flashing red signal light means STOP. After stopping, proceed when safe. Observe the right-of-way rules.
The blinking yellow and red lights mounted on the schoolbus, when on, have the same effect as traffic lights: be alert and ready to stop (yellow) and stop (red). In California the penalty for breaking the corresponding traffic rule is quite severe – $1000 of fine or revocation of driving license for 1 year.
Yellow – A yellow signal light means CAUTION. The red signal is about to appear. When you see the yellow light, you should stop if you can do so safely. If you can't stop, watch for vehicles that may enter the intersection when the light changes.
Flashing yellow – A flashing yellow signal light warns you to be careful. Slow down and be especially alert.
Yellow arrow – A yellow arrow means the "protected" turning time period is ending. Be prepared to obey the next signal which could be the green or red light or the red arrow.
Green – A green light means GO, but first let any vehicles, bicyclists, or pedestrians remaining in the intersection get through before you move ahead. If you are turning left, make the turn only if you have enough space to complete the turn before any oncoming vehicle, bicyclist, or pedestrian becomes a hazard.
Do not enter an intersection, even when the light is green, unless you can get completely across before the light turns red. If you block the intersection, you can be cited.
Green arrow – A green arrow means GO. Turn in the direction the arrow is pointing. But first yield to any vehicle, bicyclist, or pedestrian still in the intersection. The green arrow pointing right or left allows you to make a "protected" turn. This means oncoming vehicles, bicyclists, and pedestrians are stopped by a red light as long as the green arrow is lighted.
Traffic signal blackout – If a traffic signal light is not working because of an electrical power failure, stop at the intersection and proceed as if the intersection is controlled by a stop sign in all directions.