Part of Broughton Bypass is set to temporarily open to motorists from next week.
A section of the £32m project will open due to changes to the road layout as part of the latest construction.
A temporary diversion will be in place from Monday, July 17 on the A6 for southbound traffic, approaching junction one of the M55.
This short diversion will take people from the A6, towards the new roundabout on the bypass, before turning back towards the M55 roundabout.
It will be in place from approximately 9am on Monday morning until approximately 2pm on Wednesday, July 19. This will be single-lane, with two lanes on the approach to the roundabout.
Construction of the Broughton Bypass is being carried out by Hochtief, on behalf of Lancashire County Council.
Graeme Leathard, project manager for Lancashire County Council, said: "The diversion is required to carry out necessary work on the existing A6, ahead of the overnight closures from 24 July.
"We know that this work will cause some disruption to people's journeys, but hope that people will appreciate that this is a major project and we're doing what we can to minimise this disruption."
As part of work to connect the new bypass to the existing network, a section of the A6 will be closed overnight from Monday 24 July until Friday 28 July, between junction one of the M55 to Church Lane.The road will be closed in both directions between 9pm and 5am, on a daily basis, to carry out work at the M55 junction.
Graeme Leathard added: "The overnight closures are part of the latest stage of work on the new road, and include installing streetlights, re-surfacing parts of the existing A6 and associated work on the bypass. This is another stage in the work to complete this important road, which will significantly reduce congestion once it opens."
A signed diversionary route will be in operation during the closures, via the A6 Garstang Road, Eastway, Lightfoot Lane, Tom Benson Way, Tag Lane, Tabley Lane, Woodplumpton Road, Newsham Hall Lane and Woodplumpton Lane.
For more details about the project, visit the Lancashire LEP website
Last month, Lancashire motorists were warned that completion of the long awaited Broughton by-pass would be delayed until early 2018. Lancashire County Council admitted the road on the outskirts of Preston will now open several months later than planned, due to unforeseen delays and rising costs which will push the price of the project to £32m.
The new route, which was due to be completed this summer, aims to reduce traffic travelling through the centre of Broughton on the A6 Garstang Road by up to 90% and improve journey times in and out of the city.