Rail passengers on routes into Sheffield and Chesterfield face longer journeys and some service cancellations from today following a landslide onto train tracks.
The railway line through Unstone, Derbyshire, is expected to be closed for four to six weeks after the hillside above became unstable in the recent wet weather.
This has caused one of the two tracks to be closed for safety reasons.
Trains have been running at a reduced speed through the area since the New Year but from today, train services will be diverted altogether while experts stabilise the hillside.
Phil Verster of Network Rail said: “We have done everything possible to maintain a normal service through Unstone but the continuing poor weather and movement of the bank means we will need to close one of the tracks.
“This decision has been taken to protect the safety of everyone who uses and works on the railway. We thank passengers and our freight customers for their patience as we deal with this situation.
“From the start of service from today we will need to alter train services in order to divert around this area while our expert teams stabilise the hillside. The line will fully reopen as quickly as it is safe to do so.”
An hourly direct service between Sheffield and London will be maintained at nine minutes past the hour - but an extra 20 minutes will be added onto the journey time.
Service alterations also include services between Sheffield and Derby starting and terminating at Derby, and East Midlands Trains services between Sheffield and Nottingham going via Beighton.
In addition, Northern Rail services between Leeds and Nottingham will start and terminate in Sheffield, with replacement buses running between Sheffield and Chesterfield via Dronfield.
Passengers are advised to check National Rail Enquiries for specific journey information on 08457 48 49 50 or at www.nationalrail.co.uk.