Transport for London (TfL) is developing a system that advises drivers of the speed limits on the road they are using.
The software works alongside existing satellite-navigation technology and, when the speed limit is exceeded, a flashing sign or an audible signal is emitted.
The system, called Intelligence Speed Adaptation, is due to start trials on TfL's own fleet of vehicles.
After this initial test, further trials are expected to be carried out on black cabs and private hire vehicles.
The system could be available for purchase by private motorists in 2010.
It is hoped that the system will lower road-accident injuries and reduce the need for anti-speeding measures such as speed bumps.
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