Norfolk County Council started work installing a roundabout and traffic islands for pedestrians at the junction with Saddlebow Road and Wisbech Road in January.

The £75,000 project was expected to take eight weeks to complete but was severely delayed due to a number of problems including kerb alterations and a mix-up with road markings and surfacing work.

One trader told the Lynn News road markings were put down before surfacing work was completed which meant when the asphalt was laid further markings were needed.

And another spoke of his amazement at seeing a double-yellow line at least three feet from the kerb after alterations were made to the pavement to help buses negotiate the roundabout.

Barry Tice, of Tice Hairstylists on Wisbech Road, said the scheme has had a huge impact on passing trade and has questioned its value as traffic can no longer access the A47 via Saddlebow Road.

He told the Lynn News: "This has knocked trade down by nearly 50 per cent. It was the same for all the other shops down here. It is now picking up but I am still down by about 20 per cent.

"We do not need a roundabout. When it was a main road you could understand it, but not now."

Stuart Hall, of Hall's Newsagents, added: "I could not see the logic of putting a roundabout in after all these years. The natural flow of traffic coming down Saddlebow Road has been reduced since the bus gate was put in operation. I cannot see the logic of spending that amount of money."

Mark Berney, owner of Splinters on Wisbech Road, has also suffered a drop in trade and believes the enhancement goes against plans to regenerate South Lynn.

He said: "We are a small business which is struggling at the moment. What we really need is good access to the premises but people are put off when they see roadworks. We were all prepared for the stoppage, we had no choice, it needed to be done, but we could have done without the delay."

Norfolk County Council has apologised for the delays and said the alterations were made in response to concerns raised by Norfolk Green about how its new low-level buses would negotiate the junction.

A council spokesman said: "We decided to carry out on-site test runs with Norfolk Green, and as a result agreed to adjust the kerbs to give the buses more room to turn. The original cost of the project was around £75,000 and this further work has added about ten per cent to the cost.

"Although clearly it would have been better to have got it right first time, by responding quickly to Norfolk Green's concerns we have been able to put it right while contractors were still on site.

"However, this did contribute to the project over-running by around three weeks and we apologise for the inconvenience this caused.

"Some of the lines put down were only temporary and were always going to be surfaced over.

"Others will have to be adjusted to take account of the new kerb line."