Drivers have been warned to expect massive delays as a stretch of the M8 for five months from mid-February.
Major work will take place on motorway at Junction 3 near Livingston.
A major refurbishment of the bridge that carries the eastbound slip road off over the A899 will be carried out.
The nature of the works means that the slip road will be closed from mid-February for around five months.
Diversion routes will be in place for access to Livingston from the M8 coming from the west.
Eastbound traffic heading to Livingston will be directed to leave the M8 at Junction 3A, the junction prior to where the works are taking place.
The diversion will follow Carnegie Road, Deans Road and the A89 east to join the A899 Livingston Road at Dechmont Roundabout.
This will add less than one mile and typically less than five minutes to journey time – though longer delays can be expected during peak times.
Westbound M8 motorway traffic will remain unaffected.
Two-way traffic on the local A899 will be maintained when possible, however overnight closures will be required for the safety of road users during the putting up and dismantling of scaffolding on the bridge.
The scaffolding stage is expected to take place during February. Timings will be confirmed in due course.
The reinforced concrete structure, which was originally built in 1970, will benefit from a £1.3m upgrade in line with modern standards, ensuring its long-term use and safety for motorists.
Chris Tracey, BEAR Scotland’s South East Unit Bridges Manager, said: “An estimated 50,000 vehicles use the road each week. Reliance on this slip road has grown as Livingston’s popularity as a commuter town between Edinburgh and Glasgow has increased along with its reputation as a shopping destination.
“This project is about ensuring it continues to serve the community reliably for years to come.
“These improvements will reduce the need for future refurbishment and associated disruption on this scale again. It is essential for the safety of motorists and workers that the slip road is closed for much of the works programme.
“The relatively straightforward diversion route will be clearly signposted to ease the flow of traffic and ensure ongoing access to this important community hub.
“We thank motorists in advance for their patience while our teams carry out these important improvements.”
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