Construction work on a £53m redevelopment of Gatwick Airport railway station will start next autumn after funding for the scheme was secured.
Network Rail and Gatwick Airport will jointly finance the project.
It involves creating a new platform and refurbishing the concourse, including the replacement of an existing stairway with an escalator and the installation of a new lift. The track and signalling will also be upgraded.
Work to finalise the design of the scheme will start immediately with the relocation of the substation due to commence in summer 2011. Major construction work is not scheduled to start on site until Autumn 2012, with the project scheduled to be completed by the end of 2013.
Network Rail said the station in West Sussex was the busiest airport station in the UK last year.
Mark Ruddy, Network Rail’s route director for Sussex, said: "Gatwick relies on rail and this upgrade will make a real difference for passengers. By providing a better travelling experience, together with the convenience, safety and environmental benefits associated with travelling by train we hope more people will use the railway to make their journeys to and from the airport."
Stewart Wingate, the airport's chief executive, said: "I am pleased that the station - a critical gateway to our airport - will now be developed to match the improvements we are making to the airport itself.
“Separately, we are investing close to £1 billion between now and early 2013 to modernise the airport facilities for our passengers. I am pleased that the station - a critical gateway to our airport - will now be developed to match the improvements we are making to the airport itself."