A Green Light Doesn't Always Mean Go
The next time you are at the front of the lineup waiting for the signal to turn green, watch the driver beside you. Many times when the traffic signal turns green they will immediately proceed without looking to the left or right for hazards or traffic already lawfully in the intersection. A green light doesn't always mean go.
There are three situations where drivers facing a green light must not proceed immediately. Most people already follow these three exceptions, but failing to take them into account can cause confusion or a crash.
The first of the three is a situation where turning direction controls are in place. The driver may only proceed as indicated by these signals.
The second is where there is a pedestrian lawfully in the intersection or adjacent crosswalk at the time the signal is green. Drivers must yield to these pedestrians.
The final situation is where a vehicle has entered the intersection waiting to turn and has been unable to do so before the signal goes red. Cross traffic on the new green signal must yield right of way to allow the first vehicle to clear the intersection.