[♪ OUTRO MUSIC PLAYING [♪ At busy junctions, simple traffic lights may not be sufficient to allow maximum traffic flow. More complex traffic light systems allow vehicles and pedestrians to move through junctions safely, often paving the way to a clear route across the junction. This video demonstrates how these junctions work and how you as a driver should negotiate them. [♪ OUTRO MUSIC PLAYING [♪ At complex traffic light junctions, with multiple lanes, there will often be white arrows painted on the road to indicate which lane leads to which direction. There may also be direction signs, well in advance, to indicate which lane you will need. [♪ OUTRO MUSIC PLAYING [♪ Without any form of direction control from the traffic lights, vehicles wishing to turn right would have difficulty completing the maneuver because of having to cross the oncoming traffic. This may have a detrimental effect on overall traffic flow. Improved traffic flow can be achieved by using traffic lights in filter arrows. Filter arrows control the movement of vehicles according to the direction they are going, as well as the direction they are coming from. In this example, traffic wanting to go straight on or turn left is stopped, while vehicles wanting to turn right can proceed unhindered. It would also be possible for traffic emerging from other directions to be allowed to turn left without interfering with the right turning traffic. Traffic lights with filter arrows can be programmed in many combinations of direction and can change their pattern automatically, according to time of day or traffic density. This is a very common traffic light setup that you may encounter at a junction controlled by traffic lights with filter arrows. It features what looks like a normal set of traffic lights, but with an arrow stuck on the side. The arrow is called a filter arrow. When a red phase is shown on its own, it means stop. No exceptions. When a green filter arrow is shown, traffic may proceed in the direction of the arrow. This movement is permitted even if a red light is shown. Movement in any other direction is not permitted. In this example, traffic may turn right even though a red light is showing. The proviso of if the way is clear still stands. Traffic wishing to turn left or going straight on must stop. During this phase, traffic turning right should not meet any conflicting traffic, but you must still proceed with caution. Filter arrows will usually illuminate without the proceeding red and amber phase, so be alert. It is quite likely that two opposite directions will be allowed to turn right at the same time, but you only need to follow the lights controlling your stop line. Filter arrows that you will see quite commonly are left, right, and straight on. Arrows pointing diagonally are rare, but may be seen at very complex junctions. Any complex traffic light system may also use prohibitive signs such as no right turn, no left turn, and no U-turn. An often misunderstood rule is that you may not carry out a U-turn at a right filter arrow, even where there isn't a no U-turn sign. You may turn only in the direction of the arrow. There is often a pedestrian crossing showing a green phase at complex junctions, such as this, and carrying out a U-turn would put pedestrians in danger. You may also see a traffic light setup that shows a normal green phase and a green filter arrow. The solid green light indicates that vehicles may proceed in any direction, but also reassures drivers turning right that their path should be clear, however always proceed with caution. This combination of lights may also have a no U-turn sign. Reading from left to right, this traffic light phase means, proceed in any direction, except for U-turns, but traffic turning right has priority. It is even possible to see two stoplights side by side, one for each direction. This is supposed to make things clearer, but you make up your own mind.