Work has started around Churchbridge in Cannock but wide-ranging lane closures and diversions will come in from Monday.
Road workers are undertaking a £15 million project to build an underpass and widen roads ahead of the opening of the McArthur Glen retail park, off Lichfield Road.
Highways bosses need to ensure traffic keeps running at three busy roundabouts where the A5 meets the A460.
Drivers are being warned to expect disruption for the next 72 weeks as contractor Amey carries out the work with Staffordshire County Council.
According to the council, the work includes:
Access works and improvements on the A460 Eastern Way, Churchbridge Interchange and Orbital Way
Widening the A460 Eastern Way to a dual carriageway and creating slip roads to the designer outlet
Creating a new underpass and access to the site from the A460. New footpaths and cycle ways will also be installed. Before the underpass is built a temporary road will be built so no closures of the A460 are needed during peak times.
Widening both the eastern and western A460 legs of the Churchbridge Interchange to provide two lanes in both directions
Widening Orbital Way on the eastbound side, improving the Lodge Lane and Churchbridge roundabouts and installing new toucan crossings on Eastern Way.
The Churchbridge scheme will last until February but work around the retail development will continue for another year.
Traffic will be shifted onto a temporary road to ensure the A460 is not closed while the underpass is built.
Staffordshire County Council’s economic growth leader Mark Winnington said: “This is a major road project, which is supporting the development of what will become a big regional and national visitor attraction for Cannock and Staffordshire.
“It is a county council priority to ensure we have a thriving economy and McArthur Glen designer outlet will play an important part in this – bringing people into Staffordshire and making a positive impact on the county.
"The project is also bringing in improvements across the wider area which is good news for the community.
“The highways works are absolutely essential to the delivery of the overall development.
"We will see a significant increase in traffic around the area and this scheme will provide suitable access to the site and improve traffic flow on surrounding roads.
“Our highways team has put in a lot of careful planning to this project and as part of this will be the construction of a temporary road to ensure there is no closure of the A460 while the underpass is built.
“With any project of this size there will be some disruption, so we would ask people to bear with us during these essential works.”
Cannock councillor Maureen Freeman warned drivers to prepare for chaos when the full roadworks get under way on Monday.