Transport for London (TfL) has expressed regret following ongoing significant delays on the Northern line, which are now into their fifth day.

A malfunction with the signalling equipment at Stockwell station in south London has forced service controllers to “manually guide trains through this section of the network” since Sunday.

According to information from the BBC, TfL has yet to determine the root cause of the malfunction, though they have reached out to local councils, businesses, and other partners they collaborate with.

Nick Dent, TfL’s director of customer operations, stated, “Our engineers are diligently working to diagnose and remedy the issue, utilizing advanced testing equipment, and we are committed to restoring reliable service as quickly as possible.”

He continued, “We sincerely apologize to those customers experiencing delays on the Northern line since Sunday.

“We have pinpointed a fault in the signalling equipment near Stockwell that requires our service controllers to manually direct trains through this segment of the network.

“We recommend that customers allow additional time for their journeys and verify travel plans using the TfL journey planner or the TfL Go app before setting out.”