Engineers will need to build a new road before a 1,700-ton landslip on a busy cross-border railway line can be repaired.
Network Rail Scotland has revealed the extent of the works required following the landslip between Thornhill and Holywood in Dumfriesshire.
The route runs through Ayrshire between Glasgow Central and the Cumbrian city of Carlisle.
However, the stretch of line between Kilmarnock and Dumfries has been closed since the landslip on Monday afternoon.
Storm Ciara last weekend caused the River Nith to erode an embankment beneath a 50-metre stretch of track.
Stations affected include Auchinleck and New Cumnock in East Ayrshire and Sanquhar and Kirkconnel in Dumfriesshire.
Essential repairs mean that it will not reopen until Monday, March 16, causing huge disruption for passengers.
A new road and compound will have to be constructed to bring materials to the site before the embankment can be stabilised and rebuilt.
A spokesperson for Network Rail said: "Our engineers are working hard to reopen the line as quickly as possible for customers.
"Storm Ciara has caused significant damage beneath the track and we will need to rebuild the track-bed and supporting embankment before we can reopen the line.
"The landslip is located in a challenging location above the river and will also require our engineers to construct a haul road to bring equipment and materials to the site."
ScotRail last night provided an update for customers and options for how they can continue to get around.
The operator said: "The Kilmarnock to Dumfries line requires urgent repairs and is not expected to reopen until Monday, March 16.
"Engineers from Network Rail Scotland need to repair a landslip beneath a 50-metre stretch of track.
"Our trains will run as normal between Glasgow Central and Kilmarnock and also between Dumfries and Carlisle.
"In addition, our 5.42pm Glasgow Central to Carlisle and 9.12pm Carlisle to Glasgow Central services will run normally each day.
"All other services between Kilmarnock and Dumfries will be replaced by buses.
"If it's an option for you, valid ScotRail tickets and Smartcards will be accepted on Avanti West Coast and TransPennine Express services between Glasgow Central and Carlisle via Lockerbie.
"We've also arranged for valid rail tickets and Smartcards to be accepted on these Stagecoach routes: X76 Cumnock to Kilmarnock/Glasgow; X74 Dumfries to Glasgow; 43/343 Ayr, Auchinleck and New Cumnock.
"You can't use use these between 7am and 9.30am nor between 3pm and 6.30pm."
