Landslides, a train derailment and a gas explosion triggered by bad weather in the Blue Mountains, west of Sydney, caused havoc for motorists and commuters on Thursday.
The chaos began with a landslide near Wentworth Falls about 4.30pm (AEDT), which caused parts of the Great Western Highway to flood, police said.
The highway was closed to eastbound traffic and a number of diversions were put in place while structural engineers examined the scene.
The highway re-opened later on Thursday.
But another landslide near Woodford caused a minor train derailment, resulting in the closure of the railway line.
"The front wheels of a train with six carriages derailed, resulting in all trains to be stopped on the line between Springwood and Lithgow," police said.
"About 200 passengers who were onboard the train have been removed and walked off the tracks to nearby buses."
No one was injured in the incident, which also happened about 4.30pm.
About an hour later, a landslide caused problems in the upper Blue Mountains at Mount Victoria, where a railway embankment collapsed onto the Darling Causeway, affecting the southbound lanes of the road, police said.
In another incident, an underground gas line at Woodford was ruptured after it was hit by lightning.
The lightning strike caused a small fire and officers from the NSW fire brigades were called to the scene to deal with the gas leak, police said.
RailCorp said rail engineers would work throughout the night to restore train services following the Woodford derailment.
Buses were operating between Katoomba and Springwood, continuing until train services resumed.
Train services were not expected to be restored by Friday morning peak period.
RailCorp was advising morning commuters travelling to the city who usually board between Lithgow and Faulconbridge to make their way to either Springwood or Penrith Station.
Customers should allow up to an hour of extra travel time, RailCorp said.