Waveney Bridge has been partially closed and temporary traffic lights installed so repairs can be carried out to the “dangerous” deteriorating structure.
The A146 Norwich Road crosses the River Waveney by Beccles.
Suffolk Highways decided to close one lane this morning, with a spokesman for the organisation saying: "The road surface at the joint of the Waveney Bridge is deteriorating, causing the structure to become dangerous.
"To complete full repairs, a specialist sub-contractor is required but until we have established their availability, further details regarding dates and timescales remain unknown."
Suffolk Highways previously made two repairs to the bridge. However these failed on both occasions.
In an attempt to minimise disruption to commuters, the lights are manually controlled between 7am and 7pm each day.
However congestion was widespread during rush hour this morning, as the road is often a main commuter route for people from Beccles and Lowestoft travelling to Norwich,
The repairs have been described as "absolutely necessary for the safety of road users" until the bridge joint can be replaced.
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