A General Guide
Mini-roundabouts were first used in the 1970s as a 'priority to the right' control to be introduced. This was implemented at junctions where the conventional roundabout, with a kerbed central island, could not be accommodated. More recently it has been recognised that they also provide an effective form of traffic calming, reducing some vehicle speeds and often reducing accidents.
While they may be considered at any junction they generally work best at three-armed junctions and they should only be installed in areas where the speed limit is 30mph or less, and where street lighting is present.
Double mini-roundabouts may also be installed where junctions are staggered.
The physical construction of a mini-roundabout may consist of:
- Slightly raised or flush central island measuring 4 metres or less in diameter, allowing for the over-running of larger vehicles.
- Arrows to indicate the direction of traffic around the central island.
- Signing in advance and at the mini-roundabout.
- Kerb build-outs and refuges designed to align traffic and reduce speed thereby improving pedestrian safety.
- Can be introduced within the existing highway boundaries.
- May be cheaper to install than some other conventional measures.
- Are effective traffic calming measures, reducing vehicle speeds.
- May reduce accidents and accident severity, by reducing speeds.
- Allow traffic to emerge more safely from the side road.
- It is not always possible to provide satisfactory pedestrian crossing points in close proximity.
- Cyclists may experience difficulty in negotiating the mini-roundabout.
- Noise and pollution levels may be slightly increased.
- Driveways in the area of the roundabout may experience access problems.
- Parking restrictions may be required to prevent obstruction. This would require a Traffic Regulation Order (TRO).
- May attract additional through traffic due to improved traffic flow.
Surveys and engineering investigations must be carried out to determine that the disadvantages do not outweigh the advantages.
This information has been reproduced by kind permission of Bristol City Council