Works to fix a blunder which saw speed bumps installed that were too low to properly slow traffic will begin today.
Six humps were installed in Waterloo Road and five in Angel Road, during work between July and September last year.
They were put in as part of a £320,000 scheme which also saw roads resurfaced and improvements to cycle paths.
But concerns were raised the cycle-friendly road humps were not installed correctly and did not slow traffic enough.
Council officers discovered some of the humps, which should have been 75mm high, were only 35mm tall, so contractor Tarmac needs to make them taller.
It will mean road closures. From 7am on today (Tuesday, May 28) until 7pm on Friday, May 31, the southern section of Magpie Road, from its junction with Magpie Road to about 20 metres past its junction with Angel Road will be shut.
During the same period, Angel Road will be closed from its junction with Waterloo Road, while a small section of Catton Grove Road will shut for about 40 metres, past its junction with Elm Grove Lane.
From 7am until 7pm on Monday, June 3, the northern section of Waterloo Road will shut between the junctions of Angel Road and Magdalen Road.
It will disrupt First buses 21/21A and 22/22A.
And Chris Isgate, manager of the Duke of Wellington pub in Waterloo Road, said the timing of closures was not ideal, coinciding with the City of Ale Festival.
He said: "This is the first I've heard of it. It's crazy. We thought the humps were a bit small. They certainly don't slow anybody down."
A spokeswoman for Transport for Norwich said: "We are obviously disappointed that the speed humps in the Angel Road area weren't constructed in line with the original design.
"Our contractor, Tarmac, has responded to the request for this to be corrected and will also be covering the cost for the work.
"This has been programmed to take place during half-term to help minimise disruption, but we apologise for any inconvenienced caused and would like to thank those affected for their patience while the work is completed."
Tarmac said they could not say how much it would cost them to redo the work, but apologised for the inconvenience.
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