Traffic calming consists of a package of measures affecting the movement of vehicles for the purpose of promoting safety, or preserving or improving the environment. It is principally used in residential roads, shopping areas and outside of schools.
(i) Speed humps, platforms and cushions
These are probably the most effective form of traffic calming available for controlling vehicle speeds. However, they are not always popular and in some instances could cause problems for bus operators as they may cause discomfort for passengers. Humps may affect emergency services response times and could also lead to complaints about increased noise or vibration from traffic.
(ii) Road narrowings
There are three main types of road narrowing measure:
A build-out is a construction that extends from one side of the road into the running carriageway.
A pinch point is formed by extending two opposite build-outs into the carriageway.
Chicanes consist of build-outs constructed on both sides of the road in a staggered arrangement.
These measures are reliant upon a constant two-way traffic flow as it is the need to reduce speed or stop that produces the speed reducing effect. For this reason they are most effective where a balanced traffic flow exists. However, chicanes will also reduce speeds due to the need for vehicles to manoeuvre carefully through the measure. The need to accommodate larger and wider vehicles such as agricultural and heavy goods vehicles will reduce the impact that these types of measure can achieve.
Build-outs, pinch points and chicanes must be carefully sited as they can result in a loss of on-street parking space and limit access into surrounding premises. In some cases, where sufficient road width exists, a cycle by-pass can be incorporated to assist cyclists and pedestrians where no footway exists. Pedestrians can be encouraged to cross at specially designed build outs and pinch points, but chicanes are generally not suitable for this activity.
(iii) Refuges and islands
Refuges provide an uncontrolled crossing point where pedestrians can cross a road in phases. Islands, however, are not intended for pedestrian use. Both refuges and islands are placed within the carriageway, mainly centrally but they can be offset for cycle lane protection or by-pass at key positions or interchanges. In the case of refuges consideration must be given to the existing and expected pedestrian flows.
Roundabouts and mini-roundabouts can be used in urban and rural areas. In general they require street lighting and the carriageway for approaching vehicles usually has to be realigned as this will influence traffic speeds. Most can only accommodate motorised users and can be difficult for cyclists to negotiate. Roundabouts have a larger footprint than most junctions and may require a large amount of land for installation.
They work well when traffic flows are balanced. When one or more arms become busier than the rest they can stop the junction operating efficiently and in some situations traffic signals can allow the arms to be managed safely by giving specific windows for the traffic to flow. Traffic signals do not generally improve peak hour traffic flow, but can improve the driving conditions and benefit buses, cyclists and pedestrians.
Non-physical traffic calming
(i) Rumble devices
Rumble devices are textured surfaces or strips laid on the road surface as an alert to drivers where extra care should be taken. They achieve a speed reduction by creating the impression of greater speed and encouraging drivers to slow. They are often located prior to junctions and hazards, or at the entrance to villages. The impact on more vulnerable road users must be taken into account in the interests of road safety. Rumble devices do generate higher noise levels than other measures and are rarely suitable for urban or residential areas for this reason.
Gateways are used to signify the entry into a village or area, and are typically used in rural areas. The gateway can combine natural or constructed features or other traffic calming measures at entry points into villages or areas where driver expectations change, such as the start of a speed limit, village centre or traffic calmed area. Features are mainly used at the roadside as a visual cue for drivers and may include road surface treatment, paving, landscaping, planters and fencing.
(iii) Road markings
Road markings can have some effect on driver behaviour and provide important visual information. Road edge lining can provide a visual narrowing effect that makes the running carriageway appear narrower, and is often combined with the removal of centre lines where good forward visibility exists. This approach can encourage drivers to take greater care when passing. There is some benefit for pedestrians where no footway exists as it provides a narrow carriageway strip along the road edge that drivers are discouraged from entering. General hatching on wider roads can discourage overtaking whilst also visually narrowing the carriageway running lanes, but can also disadvantage cyclists who may feel intimidated by the closer travelling traffic. Coloured surfacing can provide an effective visual alert to drivers. A combination of these methods can provide drivers with useful visual aids that inform and influence their driving decisions.
For further information please contact the relevant District or Borough Traffic Team via links to the Traffic Management Services (or the County Council’s Traffic Management Group in the case of Gosport) via the Contact us link.