Buses are due to replace trains on the Brighton main line today (Sunday 1 February) for the fourth weekend running.
Trains between Brighton and Three Bridges are being replaced by buses all day, and there are no main line trains from Hove to Three Bridges either.
Train operator Southern said: “Rplacement vehicles may be busier than usual and you should allow extra time for your journey.”
Some trains between Brighton and London Victoria Three are due to run via Littlehampton, Horsham and Gatwick as engineering work takes place all day.
The main line railway closure also affects passengers between Lewes and Three Bridges.
Rail bosses said that the next scheduled weekend closure on the main line would be on Saturday 21 March and Sunday 22 March.
Buses continue to replace trains between Horsham and Dorking after a landslide led to the closure of the line.
The closure is expected to last until Monday 16 February.
