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• Truck drivers are promised jolt-free journeys through city streets thanks to a pneumatic speed hump that automatically deflates for heavier vehicles.
The Transcalm rubber hump is designed to eradicate the problems associated with conventional asphalt and concrete speed humps.
As well as deflating for car drivers when they dross it within a defined speed limit, it allows emergency service and other heavy vehicles to travel through at any speed without suffering disruption.
This is achieved by an air valve which controls the amount of air escaping from the hump at different rates for light and heavy vehicles.
A spokeswoman for Dunlop GAG, which has developed the system with highway consultants Pell Frischman, says con
ventional humps can cause neck injuries and damage vehicles.
"They also raise environmental concerns about the amount of noise and pollution they cause when vehicles speed up in between the ramps) which often leads to them being removed," she adds.
Trials of Transcalm have begun in Puddle Dock, a public highway close to Blackfriars station in London.