Essex Police have been defending their decision to keep the Dartford River Crossing closed for hours after a serious crash.
There were major delays following the incident in the early hours of yesterday.
But the force says the bridge was kept closed for investigation work and vbecause equipment used to stop vehicles falling into the Thames had been damaged.
The woman driver suffered serious injuries and was taken to hospital in London where she remains. Her passenger, a teenage boy, was also injured but was released from hospital after treatment.
The force says roadworks on Junctions 30 and 31 and drivers jumping red lights on major junctions and blocking other vehicles have added to the problems.