From 2.30am to 12pm, buses replace trains between Bomaderry, Port Kembla and Wollongong.
Trains run between Wollongong and Bondi Junction, some to a changed timetable.
The 02:39 Kiama to Bondi Junction service will run up to 20 minutes earlier than the normal timetable from Kiama to Coniston, then run to the normal timetable from Wollongong to Bondi Junction.