The 40ft in the Fens is open again after a tractor came off the road and its trailer became stuck on the embankment.
Diversions were in place around the Chatteris area and there was a major tail back of traffic along the road.
Police and emergency services tried unsuccessfully to unhook the tractor to allow traffic to pass.
Reports from the scene suggest that police feared that if the tractor was separated then the trailer could hurtle into the water.
The driver of the tractor was unhurt in the incident.
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