While the underlying cause of a jam might be an accident, a bottleneck, or drivers simply changing lanes on busy roads, it is how the drivers react in the cars behind that causes traffic to slow to a halt. Researchers say aggressive motorists, who drive too fast and too close to the vehicle in front, or timid motorists, who leave too big a gap, send a “wave of deceleration” backwards down the road until traffic grinds to a stop.

Such behaviour leads to the stop-start traffic jams which infuriate motorists.

Since 2001 the number of cars on Britain’s roads has risen considerably from 24.6 million to 31 million, leading to more traffic jams.

A report earlier this year estimated that by 2025, drivers in Britain could be wasting 656 million hours a year – the equivalent of 75,000 years – sitting in traffic jams.

Dr Jorge Laval, from the school of civil and environmental engineering at Georgia Institute of Technology in Atlanta, who conducted the research into aggressive and timid drivers said it was important to understand what causes the jams.

“Stop and go driving is a nuisance for motorists throughout the world. Not only does it increase fuel consumption and emissions, but it also imposes safety hazards,” he said.

Dr Laval, who worked with colleagues at the University of Lyon in France, found that when drivers changed their speed, they caused drivers further back to change their speed. The change in speed passed like a wave, backwards through the traffic.

If all the drivers behaved the same way, then traffic would not come to a halt. But the researchers found that in real life situations, the behaviour of aggressive and timid drivers led to the slowdown getting worse. Read more in Telegraph.