Scientists have unveiled a hi-tech sat-nav gadget aimed at predicting and avoiding traffic jams.

The Congestion Avoidance Dynamic Routing Engine (Cadre) gathers information from sat-nav devices in other cars and interprets the data to build a traffic status report that can warn drivers of potential queues.

Live information is fed to road users over GPRS to the driver's mobile phone and estimates how long the journey is likely to take if they continue on the same route. The device can then recommend alternatives.

The technology has been tested on 2,100 journeys made around Hampshire on key routes including the M27, M3 and A3.

Cadre has been developed by a consortium including the University of Portsmouth, Smartcom Software, ViaMichelin and Hampshire County Council, and could be in the shops in 18 months.

The device uses artificial intelligence software developed at the University of Portsmouth's Institute of Industrial Research (IIR).

"The system interprets live data from current traffic conditions so the motorist receives up-to-the-minute advice and can make an informed choice," said Dr David Brown, head of the IIR.

"It is designed to take the pain out of that agonising decision about whether to try an alternative route which could be equally congested."