All change at London Bridge
Because of the complexity of the work and the need to keep as much of the station operational as possible, all of the work is being phased with overall completion set for 2018.
The work includes a new and bigger concourse, which will have 66% more space for retail and station facilities. A reconfiguration of the tracks will result in nine through platforms and six terminating platforms.
Network Rail says this will mean more trains to more destinations including a connection to Crossrail services.
Two major steelwork packages, one for bridge decks and another for platform canopies and associated areas, are currently being finalised by main contractor Costain.