More than 500 yards of train tracks have been laid by railway workers between Balcombe and Maidenbower.
As well as new track, Network Rail and its contractor Colas Rail laid new ballast – the crushed stones the track sits on – and new sleepers on Saturday March 19 and Sunday March 20.
A spokesperson for Network Rail said: “This will not only provide a quieter and more comfortable ride for passengers, but new track also requires less maintenance – and hence less disruption to services.
“A length of straight rail will typically last between 30 to 40 years, so it is long lasting too. Curved rail lasts less time because it wears out.
“We realise that passengers will have been disrupted as a result of this work, with buses replacing trains between Brighton, Lewes and Three Bridges, and we appreciate their patience.”
The spokesperson added that the work had to be undertaken over multiple days, with the railway significantly quieter at weekends.
The old track and stones were removed before the new one was put in place.
Don’t miss out on all the latest breaking news where you live.
Here are four ways you can be sure you’ll be amongst the first to know what’s going on.
1) Make our website your homepage
2) Like our Facebook page
3) Follow us on Twitter
4) Register with us by clicking on ‘sign in’ (top right corner). You can then receive our daily newsletter AND add your point of view to stories that you read here.
And do share with your family and friends - so they don’t miss out!
Always the first with your local news.
Be part of it.