Would-be cable thieves threw the rail network into chaos in the North West on Monday, with scores of trains cancelled and others severely delayed.
Commuters across the region were either disrupted or left stranded after signalling was badly damaged overnight near Salford.
Services from Preston to Manchester were badly hit, as too were trains from Burscough and Ormskirk into the city.
A spokesperson for Northern Rail described the disruption as “quite significant.”
First Trans-Pennine Express said the attempted theft was having a “huge affect” on routes in and out of Manchester from the west of the region.
Work to repair the damaged cables and resume normal services was not expected to be complete until 4pm.
“It is having a pretty big impact on the rail network,” said an FTPE spokesperson. “We are unable to operate anything into Manchester Piccadilly or the airport. All our Anglo-Scottish services are currently terminating at Preston.
“It has caused an awful lot of upset for lots of travellers and we would advise everyone to check before setting out and also give extra time for their journey.”
British Transport Police said six lengths of cabling had been cut in an attempt to steal them for their metal content. The attack came late on Sunday near Salford Crescent and Ordsall Lane stations.
Foresnic teams have been examining the site, but no arrests have yet been made.