The scheme is known as the Bermondsey Dive-under.
Skanska will be responsible for the design and construction of the Dive-under, which will be formed of 11 new inter connected structures, along the line of existing operational rail viaducts.
The new grade separated junction on the eastern approach to London Bridge Station will allow Thameslink Sussex lines to cross Kent lines unimpeded on their approach to the station.
Skanska will also be responsible for associated strengthening works to a number of bridge structures and brick arches along the route.
Skanska will now work with Network Rail to finalise the scheme design and enabling works will begin shortly.
Main construction works are scheduled to start in 2014 with full completion of the project set for Spring 2017.
Greg Craig, Managing Director of Skanska’s Civil Engineering Operating Unit said:“The award of this project furthers our commitment to the rail sector where we have developed a strong reputation for delivering complex projects.
“We have enjoyed an excellent working relationship with Network Rail for a number of years, most recently at Borough Viaduct, and we look forward to developing this collaborative partnership further at the Bermondsey Dive-under project.”