PLANNED overnight maintenance work at the Dartford crossing overran this morning (Sunday, 6 April), after an infrastructure defect was found in one of tunnels.

The left-hand tunnel remained closed through the morning, with traffic only using the right-hand tunnel, the taller of the two.

Significant congestion built up on the M25 and approach roads, with remedial work not expect to conclude until around noon.

A spokesperson for National Highways said: "A planned overnight closure of the A282 west-bore DartfordTunnel northbound has overrun its agreed end time of 5am.

"This is due to an infrastructure defect discovered while carrying out routine maintenance. It will likely remain closed throughout the morning."