Buses will replace some trains on the South Coast Line on the weekend of August 19 and 20 to allow for essential trackwork.
On Saturday, August 19, buses replace trains between Port Kembla and Wollongong, and between Dapto and Waterfall, from 3am until 11am.
Trains run between Bomaderry, Kiama and Dapto, some to a changed timetable.
On Sunday, August 20, buses replace trains between Bomaderry, Kiama and Wollongong from 3am to 9.50am.
Trains run between Port Kembla, Wollongong and Hurstville or Bondi Junction, some to a changed timetable.
Also, from 4am to 6.10am on Sunday, August 20, trains run between South Coast Line stations and Hurstville only. Change trains at Hurstville to continue your journey. Buses replace all trains between Sydenham and Central.
A Transport For NSW spokesperson said works will include track repairs and the removal of high-priority defects.
"Essential trackwork will take place in the early hours of the morning, for the most part," they said/
"Sydney Trains works hard to minimise the impact to our passengers by completing work outside peak periods. We thank passengers for their patience as we work to build a more resilient and reliable network."