Types of Traffic Calming and other Engineering measures

20mph Speed Limits

Lowering speed limits alone may not have the desired effect. Currently, the Government advises that 20mph speed limits should be self enforcing. Thus it is often necessary to install traffic calming measures to ensure that speeds are no greater than 24mph.  Cost about £7,000 - 12,500 plus traffic calming. * see note below

Road humps are used to stop people speeding up rather than slow them down. They need to be accompanied by slowing features at each end of a run of humps. They are suitable for residential areas but are not acceptable on bus routes. Effectiveness decreases as spacing increases, 150m maximum. Cost per hump about £4,250.  * see note below.

Raised rectangular areas. There can be one, two or three, depending on the width of the road. Like humps they are most suitable for built up areas and need slowing features. They do not slow speeds to the same extent as humps but do give emergency vehicles and buses a smoother ride. Cost per pair of cushions about £4,250. * see note below

Similar to road humps but longer and with a flattened top, sometimes used to give pedestrians a level crossing between footways. They can also be used throughout a junction. Especially useful where there are a lot of pedestrians. If they are long enough, they provide a smoother ride for buses than humps. Often used in conjunction with humps. At £10,000 each they are quite expensive.* see note below

Localised widening or construction of footway can narrow the road and slow traffic. They reduce crossing distance and improve visibility for pedestrians crossing the road. Placed alternately they provide chicanes. Roads can be narrowed to such an extent that only single file traffic is allowed. They can also be used to provide sheltered parking. Suitable for use in urban or rural locations, as initial slowing features and as part of gateway features. Single lane build outs are not suitable for roads with high traffic flows. Cost per buildout £7,000. * see note below

Narrowing lanes, using traffic islands and/or road markings can give the impression of a more confined road and results in reduced speeds. If a road is narrowed special attention must be given to the needs of cyclists. Cost £7,000 - 32,000. * see note below

Identified by road markings, build outs, coloured surfacing and/or signs indicating that the driver is entering an area where road conditions change, for example entering an urban area or a change of speed limit. Most effective on those drivers that only use the road occasionally. Cost £7,000 -21,000. *see note beow

Often used as part of gateway schemes. Rumble strips are a change in the road surface which alert the driver by a change in the sound and feel of the car. Dragon's teeth provide a visual change and narrowing of the road. They are suitable for village entry points. Because rumble strips generate noise they can be unpopular with residents. Cost £4,250 - 5,500. *see note below

Zebra and pelican or puffin crossings may encourage more people to walk by improving safety and reducing delays crossing busy roads. They can be provided where there is a concentrated crossing movement, however there does need to be adequate visibility. Cost £20,000 - 51,000. *see note below

Refuges allow pedestrians to cross one stream of traffic at a time. They are useful where the concentration and number of pedestrians is fairly low. By narrowing the road, they reduce speeds, but the road needs to be wide enough to allow for a suitable refuge and the safe passage of vehicles and cycles. Cost £15,000.* see note below

Equal priority in all directions can slow traffic. Ideally, there needs to be a reasonably large flow on all arms for this to be effective. Roundabouts can make some turns easier which can lead to rat-running. They can be expensive and also need works to slow traffic down on the approach to the roundabout. Mini-roundabouts take up less space but need to be in street lit areas. Cost £10,000 - 210,000. * see note below

Control the circulation of traffic but can lead to faster speeds as there is no opposing flow. Traffic can increase on other roads so there needs to be a suitable route for traffic travelling in the other direction. One way streets can attract new traffic so overall traffic may not decrease. Cost from £9,250. * see note below

These provide the ultimate deterrent to rat running. They can prove unpopular with residents as they sometimes cause long diversions and increase traffic on other roads. Emergency access and the needs of services like refuse collection need to be taken into account. Cost £9,250. * see note below

If carefully used these can help to manage traffic (i.e.Protected Parking Bays). Double yellow lines maintain traffic flows in urban areas. Time restricted parking allows access to facilities within towns/villages and alleviates the problems associated with long term parking. Can be unpopular with residents and businesses. Parking problems can transfer to other roads. Cost range from £4,800 - £15,000. * see note below

Signs alone have a minimal impact on traffic speeds but they are relatively inexpensive. They are often used with other traffic calming features. Cost from £500. * see note below


These detect the speed of oncoming traffic using a radar device. If a set threshold is exceeded, a sign indicating a specific hazard or speed limit is triggered. They can be temporary or permanent. Cost approx. £9,500 for permanent. * see note below


Pedestrian safety and comfort can be enhanced by providing or improving footways on the pedestrian network. The introduction of a missing footway link may encourage more people to walk. The highway needs to be wide enough to allow for a suitable footway and safe passage of traffic. The provision of dropped kerbs and tactile surfacing may also be appropriate. 

Footway can affect parking and can be unpopular with residents & businesses and can be expensive if utility services or street lighting are affected. Costs range from £8,000 - £20,000. * see note below

* * Note: The above costs serve as a guide to the costs involved.They do include design and consultation costs,as well as that for construction.There may be economies by combining features,say in an area-wide scheme.