25 Jan 08 15:45
Speed bumps may slow traffic down, but they cause car emissions and fuel consumption to rise, according to a survey commissioned by the AA.
Researchers at the Millbrook Proving Ground found that a car capable of over 58mpg when travelling at a steady 30mph delivered just under 31mpg when it had to slow down to negotiate speed bumps and then speed up again. carbon dioxide emissions were similarly affected.
The study also found that reducing speed limits to 20mph from 30mph also affected fuel consumption and emissions (10% higher), as most engines are calibrated for maximum efficiency at higher speeds. This supports research by the Transport Research Laboratory, which reports that carbon monoxide emissions are increased by as much as 82% and nitrous oxide levels by 37% on roads with speed bumps.
AA president Edmund King said: 'Humps are a crude, uncomfortable and noisy way of slowing people down and this research has shown they are also environmentally damaging. We accept that traffic speed needs to be controlled in residential areas where there is a problem with accidents and children are playing. We think motorists are more likely to accept average speed cameras than humps.'
He added: 'The AA accepts that targeted 20mph speed limits in residential areas are popular and improve safety. However, a 30mph limit on local distributor roads may be more environmentally friendly.' (The Times)
