Gatwick Airport train station is to get a £120.5 million redesign.
Work is scheduled to start in 2017 and be completed by 2020.
Improvements will include a doubling in size of the concourse area to reduce congestion and more escalators and lifts to improve access to all platforms.
The Government will part fund the project with Gatwick and Network Rail contributing £30m each, and the Local Enterprise Partnership £10m.
The improvements will be made to meet the expected growth in air passengers.
Demand at the station is set to increase by 5 million to 20 million rail passengers a year by 2025.
Guy Stephenson, Gatwick’s Chief Commercial Officer said: “This agreement is a great example of the private sector and government working together in partnership to deliver a game changing and affordable project for the future. This new station builds on the ongoing transformation of Gatwick Airport and will deliver a first-class gateway for visitors, air passengers and the 1 million rail commuters who use Gatwick station every year.”