S-1 Traffic signal for controlling traffic

What it means

The basic three-aspect signal. Green: you may pass the signal, but you may not enter if you cannot clear the intersection before the signal changes or if it would obstruct traffic. Amber: no entry unless stopping would require sudden braking. Red: no entry. Red with amber: no entry, green is about to follow. Flashing amber: the signals are out of operation, the signs apply.