The expected cost of the £24m project has soared to £32m, after problem mobilising its utility contractor, unforeseen ground condition and an embankment collapse during wet weather.

The new 1.9km route is intended to cut congestion at a notorious traffic jam hotspot – the Broughton crossroads on the A6, three miles north of Preston.

The bypass, which will also support 650-home housing development on the former Whittingham Hospital site, was due to open last March.

Lancashire County Council has confirmed the expected opening day has now gone back to early 2018.

Additional funding for the project will come from the City Deal budget, with other highway improvement schemes amended to meet the shortfall.

Highways and transport councillor Keith Iddon, said: “We share people’s frustrations at these delays and apologise for the disruption it has been causing to people’s homes, businesses and journeys.

“We’re clearly disappointed that there has been a further delay to this scheme, and look forward to seeing the final stages completed.

“We’re working with the contractors, Hochtief, to do everything that we can to minimise the inconvenience while this major build takes place.”