Speed bump

For other uses, see Speed bump (disambiguation).

Speed bump made of asphalt

Speed bump made of rubber

A speed bump (in British English a speed or road hump, sometimes colloquially a sleeping policeman) is a traffic calming tool designed to slow traffic or reduce through traffic. A speed bump is a bump in a roadway with heights typically ranging between 3 to 4 inches (7 to 10 cm). The length of speed bumps are typically less than or near to 1 foot (30 cm); whereas speed humps are longer and are typically 10 to 14 feet (3 to 4 m) in length.

Speed Bumps are designed to give drivers an unpleasant jolt and possibly minor car damage. They are generally recommended for smaller communities with speed limits averaging approximately 15mph. A potential may exist for liability or at least a law suit for when a driver damges his car by going too fast over speed bumps .

Due to resentment amongst residents who complained in particualr of damage to cars and tyres they scraped against the large sharp-sided speed cushionss it has been documented that residents are rising up against the speed hump. In one area it was reported taht they cheerfully looked on as the labourers worked away, happy in the knowledge that years of noice, irritation, car damage and back pain were being brought to an end - the work men were digging up the speed bumps, at a cost to the tax payer of £ 460,000. .

Numerous reports have also been made of cyclists being killed due to speed bumps .

Speed bumps in some areas have been removed after protests by local residents. Such protests cite the lack of any consultation as one factor .

The use of speed bumps is widespread around the world, and they are most commonly found where prevailing vehicle speeds are expected to be low. Although speed bumps are very effective in keeping vehicle speed down, their use is sometimes controversial as they can cause noise and possibly vehicle damage if taken at too great a speed. Poorly designed speed bumps often found in private car parks (too tall, too sharp an angle for the expected speed) can be hard to negotiate in vehicles with low ground clearance, such as sports cars, even at very slow speeds. Speed bumps can also pose serious hazards to motorcyclists and bicyclists should they fall to the ground.

History

An early implementation of what might be considered to be speed humps was reported on June 7, 1906 in the New York Times. It reported that the U.S. town of Chatham, New Jersey planned to raise its crosswalks five inches above the road level, adding, "This scheme of stopping automobile speeding has been discussed by different municipalities, but Chatham is the first place to put it in practice". The average automobile's top speed at the time was around 30 MPH.

According to a publication by the Institute of Transportation Engineers, the first speed bump in Europe was built in 1970 in the city of Delft in the Netherlands.

Road humps in the UK

In the United Kingdom, vertical deflection in highways for the purpose of traffic calming typically takes one of the following forms:

• A road hump is the most common variety which are usually round-topped.
• A speed table is a type of hump with a central plateau which is both long and broad. It may include a pedestrian crossing. This type are preferred by some emergency services and bus operators
• A speed cushion is a raised portion of road with a flat top only extending over part of the carriageway width. Cushions can be used singly, in a pinch point, or in pairs or triples.
• Rumble strips are an uneven road surface which is now only used in rural areas and retail parks because of the noise.

The Department for Transport defines the regulations for the design and use of road humps.

Disadvantages

Local authorities know that speed humps have disadvantages.

• The city of Modesto in California, U.S. produced a fact sheet which contains the following disadvantages:
  • Slow response time of emergency vehicles;
  • May divert traffic to parallel residential streets;
  • There is a possibility of increased noise and pollution for residents living immediately adjacent to the speed humps.
• The British town of Eastleigh state the following as disadvantages:
  • Can cause damage to some vehicles;
  • Can increase traffic noise especially when HGV’s pass by;
  • Signs, street lighting and white lines are all required and may be visually intrusive;
  • Can cause discomfort for drivers and passengers;
  • Can cause problems for emergency services and buses.
• The Association of British Drivers is critical of speed humps claiming:
  • Drivers are distracted by the bumps, therefore ignoring other hazards such as children;
  • Humps can impede or slow emergency vehicle access to areas.
• In 2003, the chairman of the London Ambulance Service, Sigurd Reinton was reported as claiming that delay due to speed bumps was responsible for up to 500 avoidable deaths from cardiac arrest each year, he later denied the statement. It is also reported that
  • Increase pollution as traffic travels in a lower gear using signifcantly more fuel per mile;
  • Humps are a substitute for a lack of enforcement;
  • Humps increase noise by both traversing over the bumps and by using more engine revs than normal;
  • Humps cause spinal damage or aggravate chronic backache.

Dynamic speed bumps

Dynamic speed bumps are a recent innovation which differ from conventional speed bumps by only activating if a vehicle is travelling above a certain speed. Vehicles travelling below this speed will not experience the discomfort of a conventional speed bump. Dynamic speed bumps may allow the passage of emergency vehicles at higher speeds.

In a design by British company Dunlop Transcalm, a rubber housing is fitted with a pressure valve which determines the speed of a vehicle. If the vehicle is travelling below the set speed the valve opens allowing the bump to deflate as the vehicle drives over it, but remains closed if the vehicle is travelling too fast. The valve can also be set to allow heavy vehicles, such as fire trucks, ambulances and buses to cross at higher speeds. Dunlop Transcalm claim that their dynamic speed bumps reduce or eliminate negative effects of speed bumps such as increased noise and pollution, uneven traffic speed, and impeding emergency vehicles. Each 'smart hump' reportedly costs between £2,500 and £4,850.

See also

• Jiggle Bars - A series of precast concrete blocks 50 to 100mm wide, projecting 15mm above the road surface. Produce a rumbling noise and a jolt to the driver.
• Rumble strip
• Speed hump
• Speed table

External links

• London Assembly, London's got the hump, April 2004. An examination of speed humps conducted by the London Assembly’s Transport Committee.
• Traffic Logix Guide to Developing Traffic Calming Program