An update to Hai-Etlik
's description of British traffic lights
First a quick Point of Information: over here, the yellow light is termed amber.
At standard lights for controlling traffic, the sort of thing you might find at a road junction. These have four phases:
- Red -- do not go
- Red and Amber -- prepare to move off
- Green -- go (if it is safe to do so)
- Amber -- slow down and stop unless it is not safe to do so
At pedestrian crossings which are controlled by traffic lights, there is an additional phase, flashing amber. This means that traffic may proceed if no pedestrians are on the crossing but otherwise the vehicles must wait, and it is accompanied by a flashing green man on the pedestrian crossing signals.