Network Rail said:Works to repair and reopen the viaduct, on the West Coast Main Line, are to finish ahead of schedule following an intensive seven-week engineering project to save the vital structure from collapse.
The Victorian-built viaduct had been severely weakened and left close to falling into the River Clyde by flood damage caused by Storm Frank on New Years Eve.
The viaducts second pier was left on the brink of failure when floodwater scoured out much of its foundations.
Engineers had to work round-the-clock to divert the River Clyde and stabilise the structure following Storm Frank.
The incident also damaged the second piers steel bearings, which support the bridge-deck and track above the pier, a non-load-bearing section of the viaducts third pier and the structures north abutment.
Over the weekend, engineers installed new steel bearings on the viaducts damaged second pier and constructed a new concrete plinth on the top of the pier to support them.
With the bridge-deck successfully raised back into position last week, the recovery works are now progressing two weeks ahead of the March reopening date previously announced.
Engineers have taken advantage of a break in the weather conditions and the earlier than expected arrival of the new, custom-made bearings to accelerate the recovery programme.