Commuters travelling between Salford and Wigan will face rail disruption all day due to a signalling problem.
No trains will run between Salford Crescent and Wigan Wallgate.
Services will either be cancelled or diverted through Bolton, according to the National Rail website.
A rail replacement bus will run between the two stations.
Northern routes affected include services between Leeds, Blackburn, Manchester Victoria and Wigan North Western, Wigan Wallgate, Southport and Kirkby.
A post on the National Rail website says: "A fault with the signalling system between Salford Crescent and Hindley via Atherton means that buses are replacing trains between Salford Crescent and Wigan Wallgate.
"Services may also be cancelled or diverted via Bolton.
"We anticipate disruption will continue until the end of the day."
Bus services will run from Wigan Wallgate to Salford Crescent calling all stations in between at 5 minutes past the hour and 35 minutes past the hour.
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Buses will also run at 5 minutes past the hour and 35 minutes past the hour in the opposite direction.
