A speed cushion (also known as a speed bump) is a short raised rounded device in the centre of a road lane and are one of the most cost-effective means of reducing speeds. This is similar to a speed table but is a raised section with a gap between them.
Speed tables are more effective than speed cushions in reducing speeds. Speed cushions allow wider vehicles to straddle the cushion allowing buses and emergency services to pass along a route. They are designed to be slightly wider than a car so car drivers will need to slow down and drive over the centre of the cushion to reduce discomfort.
While speed cushions can be used as an effective way to reduce speeds, they aren’t an appropriate form of traffic calming for entry speeds as they result in late braking and a risk to motorists of loss of control. Speed cushions may create noise and vibration which could impact local residences and may cause traffic to divert to other routes. In order for speed cushions to be effective and meet the Department for Transport’s (DfT) guidance, multiple sets of cushions need to be installed on each approach. Speed cushions can only be installed where there’s a suitable system of street lighting throughout the residential area.
Due to the impact on pollution, central Government is looking for Local Authorities to reduce the use of speed cushions and remove them where appropriate, which would make it harder to justify installation.
Typically the costs are approximately £100,000 – £200,000.
All costs stated are for guidance only.
Figures provided are estimates and are reviewed annually, with all costs subject to a site survey assessment.
For further guidance see the Department for Transport: Local Transport Note on Traffic calming