Network Rail is to spend £30 million increasing space on the concourse and adding ticket gates at London Victoria station.
The plans includes opening up the concourse serving platforms 15-19 with an access route created from platform 14 and the existing escalators to Victoria Place shopping centre.
To create space for an extra 25 ticket gates (including eight new accessible ones), the Gatwick Express ticket windows will be moved and some retail units moved elsewhere in the station.
Work will start from September with relocation of the Gatwick Express ticket office, followed by the Kent gatelines on platforms 1-7 in November and the Sussex equivalents later in the year. The project, which will take place alongside London Victoria resignalling work, is due for completion in late 2023.