The main railway line connecting Brighton and London has reopened, following a nine day closure for major engineering works costing £15 million.
Engineers worked to rebuild Copyhold Junction near Haywards Heath which controls the movement of trains in out of Ardingly freight branch and Brighton, in a bid to tackle delays for Southern and Thameslink passengers.
Workers also upgraded a number of embankments to reduce the risk of landslips.
Network Rail says the nine day closure meant it could avoid more than 20 weekends of closures.
The line was closed between Three Bridges, Brighton and Lewes from Saturday 19 to Sunday 27 February 2022.
Katie Frost, Network Rail's Sussex route director, said: "The Brighton Main Line is one of the UK's busiest routes and the rail infrastructure is among the oldest and most intensively used.
"These works are absolutely vital to improving performance so we can give passengers a more reliable train service.
"Doing the work in a longer 9-day closure means we can get more work done, more quickly, avoiding 20 separate weekend, evening and bank holiday closures which would be even more disruptive to passengers, the people who live by the railway and the wider economy."
Further closures will take place on the following dates, for preparation and follow up work:
The work has been years in the planning, with engineers carrying out additional jobs including drainage and brick repairs in tunnels as well as maintaining embankments at Haywards Heath, Lewes, Balcombe and Hassocks.
The work is all part of the wider Sussex Upgrade programme, which is investing more than £750 million from 2019 to 2024 to improve the railway for passengers.