In December, the line was closed for nearly a week while teams carried out a full clean-up operation.
Some emergency repairs were made to the railway infrastructure, but Network Rail said “extensive work” was now required to make the route “fit for the future”.
Rails, sleepers and ballast – the stones below the track – will be replaced, and it is hoped the new track will last for more than 50 years.
The platform structure will also be repaired and fully resurfaced.
Engineers will also take the opportunity of the closure to finish upgrading platform one at St Margaret’s station.