Traffic signals and other lit signs are installed to: 

• improve road safety where accidents have occurred;
• manage traffic flows where congestion occurs; or
• provide safe crossing facilities for pedestrians and cyclists

There are a variety of traffic signals:

• signal controls at junctions - these are the usual traffic signals at junctions that give priority to different streams of traffic. Most sets of traffic signals at junctions also include facilities to control pedestrians crossing;
• pelican crossings have the green man indicator at the opposite side of the road to the pedestrians. These crossings have a flashing green man and a flashing amber traffic light;
• puffin crossings are the next generation of crossing with the pedestrian indicator on the same side as the pedestrian. There is no flashing green man or amber traffic light;
• toucan crossings allows both cyclists and pedestrians to cross and will show a green cycle symbol at the same time as a green man;
• pegasus crossings allow horses to cross and have special arrangements for the horses to wait;
• vehicle activated signs - these signs can show many different things - most commonly they indicate the speed limit and slow down. They house speed detection equipment and are set to be triggered when speeds exceed a threshold;
• wig wags - These are flashing amber lights which are triggered to go off when an event happens, such as a Fire Engine leaving the fire station.

 More information about traffic signals and signs, markings and crossings can be found on the DirectGov website