Speed bump

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A speed bump (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. Speed bump heights range from as little as 2 inches to as much as 6 inches^{[citation needed]}, and they can vary in length from less than 1 foot (30cm) to as much as 10 feet (3m)^{[citation needed]}.

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.

Contents 1 History 2 Road humps in the UK 3 Disadvantages 4 Dynamic speed bumps 5 See also 6 References 7 External links

[edit] History

An early implementation of what might be considered to be speed humps was reported on 1906-03-07 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". ^[1]

Prior to the invention of the automobile and the widespread use of smooth asphalt or concrete pavement, street vehicles could not travel at the sort of speeds at which speed bumps are intended to reduce^{[original research?]}.

According to an Institute of Transportation Engineers publication the first speed bump in Europe was built in 1970 in the city of Delft in the Netherlands. ^[2]

[edit] Road humps in the UK

In the UK, vertical deflection in highways, designed for Traffic calming, is of the following forms:

• Road hump is the most common variety which are usually round-topped.
• 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
• 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 - 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. ^[3]

[edit] 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^[4]: 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^[5]: 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 ^[6]: 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^[7]: . 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^[8] or aggravate chronic backache.

[edit] 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. ^[9][10]

[edit] 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 - A textured surface producing a rumbling noise and a vehicle vibration
• Runaway truck ramp - A lane of soft sand or earth or loose gravel to stop an out of control vehicle

[edit] References

[edit] 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