Highways officials have said that the ongoing roadworks on the A47 will continue for another two weeks due to additional vital repairs.
The work, which started in early June, has been scheduled to finish in the morning of Tuesday August 12.
The contraflow and 30mph speed limit will remain in place until Friday August 8.
Ranjit Mistry from the Highways Agency said: 'I would like to thank drivers on the A47 for their co-operation so far.
'The maintenance work, part of the Government's investment in infrastructure, will ensure the thousands of people that use bridges on the A47 near King's Lynn every day will continue to do so safely.
He added: 'The delays are due to additional repairs needing to be carried out to the bridges and it rained when waterproofing work was scheduled to take place.'
The work involves rewaterproofing and resurfacing the River Great Ouse Bridge, the River Nar Bridge and the Harbour Junction Bridge.
Vital bridge maintenance work on three bridges on the A47 near King's Lynn will continue into early August due to unavoidable delays.
Road users are advised to plan their journeys in advance and leave extra time if necessary.
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