The main route between the west coast and central Scotland will be closed for seven days, after heavy rain dislodged stones that were holding up the track.
Network Rail has said the West Highland Line between Glasgow and Oban, and Glasgow and Fort William will remain closed for at least a week to repair damage at five sections of the track.
Due to severe flooding on the line, stones which support the track were washed away and until these parts of the track have been re-laid, Network Rail says it is unsafe to operate trains.
Scotrail said securing a bus replacement service is proving difficult at the height of the tourist season.
The route will be closed while engineers make an assessment of the damage to the iconic railway line during the busiest month of the year for its operator Scotrail.
Susan MacKay Brown from Dalmally said she was due to be at an important hospital appointment in Glasgow when she was told the train was cancelled.
She said: “I have waited for months for my appointment, so we raced down the road in the car. But I don’t know what other people will do.”
Jodie MacKay, from Mull, only learned the news of the closure when she had already been travelling for four hours, she said: “It was chaos at the station on Monday morning, no one knew what was happening.
“We get a discount on the train with our West Highland railcard and it is triple the price on the bus.”
Mary Miller, from Spean Bridge, was heading to Glasgow to look after her grandchildren, she said: “If this had happened in Falkirk I am sure all the stops would have been pulled out to sort out the transport immediately.”
A spokesman for Scotrail said: “The line will remain closed for the next seven days while engineers carry out vital repair works.
“We’re working hard to source alternative transport and we’re sorry for the inconvenience this will cause some of our customers.
“We will keep customers updated over the coming days.”
A Network Rail spokesman said: “Our engineers are working hard to fully assess the repairs required to reopen the line as quickly as possible for customers.
“The flooding over the weekend has caused significant damage at multiple locations along the line and we will need to rebuild the track-bed and supporting embankments in some locations before we can reopen the line.”
The Caledonian Sleeper has cancelled its service.
