Rail passengers in Lancashire were warned of disruption this afternoon.
Train operator Northern tweeted that there was a problem with signals at Carnforth.
There may be delays or even cancellations.
Northern said: "Due to a fault with the signalling system between Barrow in Furness and Preston, some lines are blocked.
"Train services running through these stations may be cancelled or delayed by up to 30 minutes,"
Services were running normally by about 6.30pm