Speed bumps 'increasing harmful emissions'

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London taxi driver Tony Bailey in the City of London testing out the latest revolutionary road hump unveiled by manufacturers which deflates for motorists driving under the speed limit.  *  The "intelligent" road humps were developed in Manchester to deflate if drivers go below a set speed limit, or for emergency vehicles. Known as Transcalm, they could reduce the number of injuries caused by conventional sleeping policemen made from concrete, manufacturers claim. They are to be tested out in the City of London with a view to beingintroduced nationwide.   *  Conventional road humps have drawn criticism for punishing emergency vehicles, causing neck injuries, damaging car suspension systems and raising noise levels.

Speed bumps should be scrapped because they contribute to air pollution, according to a report from a health watchdog.

A report in The Telegraph said the National Institute for Health and Care Excellence (Nice), had suggested that other traffic-calming measures, encouraging drivers to remain at a constant speed, would be better for combating air pollution.

It comes after research from Imperial College London found that forcing motorists to brake and accelerate caused increased harmful emissions.

The Telegraph reported that other schemes proposed by Nice included separating cyclists and cars by using foliage such as bushes and trees and banning 'car idling' outside schools and retirement homes.

Further suggestions included redesigning houses to move living rooms to the rear and reduce the effects of pollution.

The Telegraph said draft guidelines concluded that planners must take air pollution into account when designing traffic-calming measures, with physical measures built to "minimise sharp decelerations and accelerations".

The report suggested that speed limit signs could be a useful alternative to bumps, and that variable limits similar to those found on motorways could also be used.

Ralph Bagge, leader of South Bucks District Council and deputy chairman of the Nice guideline committee, told The Telegraph: "Smooth driving reduces emissions and stop-start acceleration and deceleration is harmful. It is putting out more through the tail-pipe but secondly braking is also grinding bits of very fine particulate matter which goes into the atmosphere.

"Where a 20mph limit is appropriate, humps and bumps aren't the most effective way of doing it. Most people tend to accelerate up to about 30mph, hit the brakes and do about 15mph over the hump, then accelerate again.

"In emissions terms that's a very ineffective deterrent. We would like there to be a better way of doing it than that."