The variable speed limits aim to tackle congestion at the Dartford Tunnel

Variable speed limits are being brought in on a section of the M25 in Kent from today in a bid to tackle congestion.

The technology is going to be used between J2 at Darenth and J3 for Swanley to ease queues leading up to the Dartford Tunnel.

It means the Highways Agency can display speed limits, depending on road conditions, on screens above the motorway.

The limits will be mandatory, with Kent Police using cameras to issue speeding fines.

Sensors in the road will detect the speed, volume and flow of traffic to calculate the best speed to keep traffic moving.

John Martin, from the Highways Agency, said: "The controlled motorway system will bring great benefits to road users on this busy section of the M25 - helping to reduce congestion and make road users' journeys safer and more reliable by smoothing traffic flows.

"This system is already being used successfully in other areas, including on the western section of the M25 near Heathrow and on the M20 between junctions 4 and 7 in Kent.

"On the M25, where the system has been in place since 1995, it has reduced collisions by 10% and provided the benefit of smoother, more reliable journeys at peak times.

"In addition, an overall reduction in vehicle emissions of between two and eight per cent has been recorded on the M25."

The variable speed limits comes after a public consultation in 2009.