The smart road hump

An "intelligent" road hump that recognises a speeding motorist has been hailed as a road safety breakthrough.

The inflatable hump stays rock-hard when a speeding car passes over it. But when a motorist drives over slowly it deflates, laying flat on the road surface before popping into shape again. A valve inside the £4,000 rubber humps can be set to collapse at speeds as low as 15mph.

But it can give way to ambulances and buses as it is sensitive to their weight. Called Transcalm, it is made by British firm Dunlop Trancalm and has been tested in the City. If successful, it may be used across London.

Corporation of London highways director Joe Weiss said: "It's excellent, the first traffic-calming device that can tell the difference between slow and fast drivers."