Speed humps are provided to reduce vehicle speeds and improve road safety.
There are a number of different types of speed humps and each one is used for a particular purpose.
A 'normal' speed hump (also known as a sleeping policeman) is provided across the full width of the road. These are usually between 75mm and 100mm high, and are used in residential roads where high vehicle speeds would be detrimental to residents' safety. These are the most effective type of traffic calming feature in reducing vehicle speeds.
Speed cushions are smaller than speed humps and do not stretch across the full width. Typically, there will be two cushions at each location, each being 75mm high and having a width of approximately 1.7 metres. They are provided on roads where bus services operate or where the emergency services use it as a 'strategic route' to gain access to adjoining areas. They are designed so that larger vehicles, such as ambulances, fire engines and buses, can straddle the cushion without having to ride up and over the cushion. Smaller vehicles, such as cars, cannot straddle the cushion and have to drive over them.
Speed tables are provided across junctions to provide a speed reducing effect on each leg of the junction, and in certain location also provide a level crossing point for pedestrians. They are mostly suited to bus routes or routes where the emergency services use it as a 'strategic route' to gain access to adjoining areas. Drivers of these larger type of vehicles find speed cushions easier to drive over, but they are not as effective as a standard speed hump.
Problems for larger vehicles
There is sometimes opposition from the Fire Service, Ambulance Service and bus companies to the use of speed control humps. The Emergency Services object because humps increase their attendance times for emergency calls and they consider this risks the lives and property of the people. They do however, agree that speed humps help to save lives by slowing traffic down.
The Ambulance Service and bus companies object because of the discomfort and possible injury that may be caused to their passengers and staff.
Regulations
There are regulations governing the layout of speed control humps. There must be a form of "slowing feature" on the approach to the first hump - usually formed by a change of priority (traffic entering the system has to turn sharp left or right into the road, or has to "give way"). Sometimes mini roundabouts are used at the start of a system of humps.
For further information regarding speed humps or to suggest an area for speed reduction measures, Bolton Council's Transportation and Road Safety Team can be contacted using the details at the top of this page.