Drivers and cyclists are facing three weeks of disruption from next week, because £25,000 needs to be spent to fix a ring road roundabout which was only completed in the summer.
Council bosses only completed nine months of work on the Dereham Road/Sweet Briar Road roundabout in June, but £25,000 already needs to be spent to fix it.
That £1.6m work on the roundabout, to make it bigger and parts of the road wider, started in September last year, with the goal of cutting congestion and reducing journey times.
However, the construction caused months of disruption, culminating in a complete five-day closure of the road in the summer.
Highways chiefs say the changes have sped up traffic. But they say repairs are needed because lorry trailers have been running over a section of angled kerb on the roundabout which gives access for maintenance vehicles.
The material used to reinforce the roundabout has become loose and has lifted up out of the ground, so council bosses want to spend the £25,000 to install a concrete ring as replacement reinforcement.
They say that will reduce the risk of having to do emergency repair work in the future. But the work, which will start on Tuesday, January 8, will last for three weeks.
It will see one lane closed on all approaches to the roundabout.
And there will be one night of four-way temporary traffic lights from 7pm on Friday, January 18 until 5am on Saturday, January 19.
Council bosses say any noisy work will be completed by 11pm to minimise disruption.
John Fisher, Norfolk County Council's chair of Norwich highways agency committee, said: 'The new Dereham Road/Sweet Briar Road roundabout has been a success story for our network, with journey time data showing improvements to traffic flow in the area since its completion.
'As with all schemes, we monitor the need for any follow up work and although the roundabout is big enough for lorries to stay in lane all the way around, some vehicles overrunning the central kerb has caused enough damage to need a different approach to reinforcement.
'We know that the disruption will be frustrating for those affected and we'd like to thank everyone for their patience.
'The reason for carrying out this work sooner rather than later is to avoid the potential need for emergency repair work further down the line, which could cause unplanned lane or even road closures.'
More work in streets around Prince of Wales road
The next phase of work in a multi-million pound shake-up of how traffic uses the area around Prince of Wales Road in Norwich will start on Monday.
Highways bosses are spending £2.75m on a string of changes in the area, which has already seen King Street closed to traffic.
Four months of work is about to begin, but council officers say it should not cause 'significant delays'.
Work will be done to Rose Lane and Cattle Market Street. Work includes landscaping and wider pavements, new crossing facilities and a new cycle track to join up with the cycle lane on Cattle Market Street,
The bus lane in Rose Lane will also be removed, but the existing two lanes for general traffic are being retained.
Closures to vehicles will be in place on the King Street junctions either side of Rose Lane, with diversions in place for access. A seven-week closure of St Vedast Street will also be needed from the start of the work.
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