How traffic flow is controlled

The traffic flow of a big city is carefully controlled and of course traffic lights play the main part. Bus detectors are installed at traffic lights in Royal Greenwich so that when a bus approaches a junction the lights automatically give it priority over other traffic.

One-way streets, banned turns and no-entry

These can stop commuter 'rat runs'. One-way restrictions may cover the whole street, or a short length at one end, sometimes referred to as a 'one-way plug'. There must be a suitable alternative route for traffic travelling in the opposite direction to the one-way street, or for traffic needing to turn in the direction of the ban.

Road closures

Roads can be closed by a barrier with an emergency access gate for police, fire and ambulance vehicles.

Road junctions

Junctions may have a 'give way' line, 'give way line and triangle marking', or a 'give way line, a triangle marking and a give way sign'. Some junctions may have a 'Stop' sign and marking. There are strict criteria, relating to visibility distances of approaching traffic, which must be met before 'Stop' signs can be introduced.

A 'junction entry treatment' is placed across the carriageway of a minor road at a junction. This shows motorists that they are leaving a main road and entering a residential area. It also means pedestrians crossing the junction get right of way. This treatment often has a speed table, kerb build out and gateway features. Many side roads near Red Routes have junction entry treatments.


Standard roundabouts are intended to solve problems at junctions where there is heavy right turning movement (for instance lots of vehicles turn right).

Mini roundabouts are introduced to reduce accidents, by slowing traffic, and to assist right turning movement. Their advantage over full-size roundabouts is that they can often be accommodated within the existing road space, without expensive road widening.

Traffic calming

Funding for traffic calming schemes comes from Transport for London. Contact the Traffic Management team to find out which schemes are planned for your area. Some roads, such as those used for bus routes, will not be suitable for calming measures.