Drivers on the M9 face two months of disruption during repairs to new lanes which have cracked just three years after they were built.
A four-lane section north of Newbridge in Edinburgh will be narrowed to two lanes in each direction along with a 40mph speed limit from Monday.
The stretch between the River Almond bridge and junction 1a will also go down to one lane at certain times overnight and at weekends.
Drivers are urged to take alternative routes or allow extra time for journeys, especially to nearby Edinburgh Airport.
A fourth lane which was added to the motorway as part of the junction upgrade in 2013 is thought to have sunk as part of settlement of a new embankment it was built on.
The cost of the work will be paid by the contractor, SRB Civil Engineering, a consortium of John Sisk and Son, and Roadbridge.
The Scottish Government’s Transport Scotland agency said there had been an unforeseen problem with the “interface” between the existing and new lanes.
A spokesman said: “The issue was first notified in early 2014. The road has been closely monitored over the intervening period.
“It was decided to ensure the full extent of the problem was known to allow for a single repair to make sure any disruption was minimised.
“There will be no cost to the public purse.
“As is standard on most infrastructure contracts, there is a mechanism to deal with this type of issue. The details of costs are commercially confidential.”
Transport Scotland roads and infrastructure manager Steven Brown added: We have an inspection regime in place to monitor performance of the road, this has identified the need for essential repair work to the road surface.
“Our advice to road users is to avoid the area if possible and consider using public transport or alternative road routes.
“While every effort has been made to minimise disruption, we recommend road users allow additional time for their journey.
“I would strongly urge those heading to Edinburgh Airport to check ahead and allow sufficient time.”
Neil Greig, of motoring group IAM RoadSmart, said: “You couldn’t make it up.
“This is really bad news for drivers on the M9 and the surrounding area.
“In such a key location, delays are inevitable even if two lanes can be maintained throughout the works.
“The only crumb of comfort is the problem is being fixed ‘under warranty’ at no extra cost to the [Scottish] government, but at lots of extra cost to drivers and businesses.
“IAM RoadSmart has welcomed the current levels of capital investment in road schemes across central Scotland, but road users will need reassurance no corners are being cut on quality, and the lifespan of the new roads will match that of their predecessors, usually measured in decades not years.”