Blackfriars mainline station is to close for two months as part of the £5.5bn Thameslink project.
A new station, which will be the first to span the Thames, is being built as part of the Bedford to Brighton line upgrade.
Construction of the upper concourse has finished and the closure in November will allow work to switch from the west side to the east side of the bridge.
Blackfriars Tube station closed for two years in March 2009 under the project.
The completion of the upper station concourse paves the way for the track "switch" at Christmas.
This will involve work on the the tracks moving from the western side of the bridge to the eastern side - creating the final track alignment for the redeveloped station.
Trains will continue to run through the station for the majority of the closure - from 20 November until 17 January - and passengers will be able to use the nearby City Thameslink station.
Work to extend platforms to accommodate 50% longer trains on the line has been completed at St Albans, Luton Airport Parkway and Mill Hill Broadway.
In total 12 stations will undergo work to extend platforms and the first 12-carriage trains are due to begin running in December 2011.
The redeveloped Blackfriars station, which will have an entrance on the South Bank, is due to open in spring 2012.