Speed Humps

The County Council recognises that road humps are an extremely effective means of controlling vehicle speeds and that they can play an important role in helping to cut personal injury accidents in line with the Government's road safety strategy.  Their effectiveness relies on creating a vertical deflection to vehicles as they pass over them which in turn transmits discomfort to the drivers and other vehicle occupants.  For this reason alone they may not always be popular with the very people who would gain from reduced traffic speeds.

There is usually opposition from the Police, Fire Brigade, 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 thus risk the lives and property of the people.  The Ambulance Service and bus companies object because of the discomfort and possible injury that may be caused to their passengers and the increased wear and tear on vehicles, particularly buses going over speed tables every day.  These along with any objections received from the public are reported to the Planning and Regulation Committee for their consideration on a scheme specific basis.

On traffic sensitive routes, i.e. bus routes, speed cushions are used in preference to speed humps.  The speed cushions allow larger vehicles, buses, emergency vehicles, HGVs, across them with minimal of deflection and therefore giving a smooth ride to the occupants whilst still reducing the average speeds of private and small vehicles.  However, speed control humps can sometimes lead to complaints about increased noise and vibration from traffic.

In order to maintain continuity, road humps are designed in line with national standards recommended by The Department for Transport (DfT).  The shape of speed control humps can have either flat tops or round tops and will generally be between 50 mm and 100 mm high minimum 2.75 metres long and extend over the full width of the road.  Many local authorities have, however, adopted the 75 mm high hump as a standard as this has been found to be effective in reducing traffic speeds to around 22 mph.  The 100 mm high humps reduce speeds to 17 mph on the hump itself but then tend to lead to speeds rising to 35 mph between the humps, causing excessive acceleration, braking and increased pollution.

Flat topped humps can be of any length and are often known as "speed tables".  They are sometimes used to reduce the impact on long wheel base vehicles such as buses.  A variation to speed tables, known as "speed cushions" may also be used along bus routes or roads which are of strategic importance to the emergency services as these will be of reduced width within the lanes of traffic and thereby allow the wider axle vehicles to pass without the same level of disturbance for passengers or patients who may be in a critical or sensitive condition.

However, speed humps, platforms and cushions have been proved to reduce traffic speed and they have been installed in many locations to good effect.  They are also used in 20 mph Zones to encourage self-enforcement of the reduced speed limit.

Requests for speed humps, or for more information, should be sent to the appropriate Divisional Highways Manager, details given by 'clicking' on the Contacts tab at the top of the page.