The A500 Pathfinder project through Stoke-on-Trent, Staffordshire, has been in place since 2004 and was meant to be completed later this year.

The scheme aims to reduce congestion in the area with the building of two roundabouts and underpasses.

A project spokesman asked drivers to "bear with them" while they reconstruct the carriageway.

The Highways Agency said the latest delays were caused by factors they could never have predicted.

'Potential for delays'

From Friday, extra traffic lights and a contraflow will be in place at Whieldon Road, south of City Road.

Graham Dakin, project manager said: "There is potential for a few more delays and we would ask drivers to bear with us.

"It is an essential piece of the jigsaw as we have to reconstruct the carriageway.

"We have looked at various alternatives... but this is really the only way we can do it."