Crews are working fast to re-open the Blue Mountains Line after the weekend landslip at Leura but it is likely to take weeks rather than days.
Sydney Trains has secured the track infrastructure and is now working to stabilise the land.
Buses are operating between Springwood and Mt Victoria.
It may take a number of weeks to repair the line, according to Transport for NSW. A large metal stanchion, which holds up the overhead power lines, was damaged when the landslip occurred and needs to be removed before further work can take place.
Engineers have been on site assessing the damage, however at this stage, it is unsafe for reconstruction work to resume because of the chance of further land movement
Infrastructure including the track bed, ballast and safety equipment has been washed away.
Once the corridor is safe, engineers will begin to rebuild the embankment and infrastructure. This will include earthworks, track reconstruction, signalling and overhead wire repair
To provide a consistent service, more frequent four-car trains are running, rather than running fewer services with eight cars.
A spokesman for the department said there are 52 Intercity train cars trapped on the western side of the landslip. They are in stabling tracks at Katoomba and Mt Victoria.
The minister for regional transport and roads, Paul Toole, said at this stage the Leura work wasn't expected to delay reconstruction works taking place further up the line.
"At the end of last year, 25 kilometres of track was significantly damaged by bushfires between Mount Victoria and Lithgow, with thousands of kilometres of communication, electrical and signal wiring lost," Mr Toole said.
"Sydney Trains' engineers worked tirelessly to develop temporary systems to allow limited rail connectivity and to safely operate a limited number of freight and passenger trains from January 21.
"Unfortunately with the recent landslip at Leura, these services have been temporarily suspended once more. We understand this ongoing closure may cause some frustration for customers, but we thank you for your patience as we continue to rebuild the rail corridor."
Transport for NSW is working closely with freight operators to provide alternative routes. Passenger services will be replaced by coaches or buses for all or part journeys.
Customers travelling along the affected lines can check the latest information and plan their journey through trip planning apps or online at http://transportnsw.info.
