Commuters who rely on one of the busiest Tube lines are facing a fourth day of delays and disruption, with Transport for London (TfL) still warning Londoners to “avoid the Northern line”.
According to TfL, the problem comes from “a fault with the signalling equipment” around the Stockwell area, in South-West London, but officials are still not clear what caused the technical failure in the first place.
For now, TfL’s service controllers are having to manually guide each tube train through this section of the line, causing severe delays across the entire network.
Nick Dent, TfL’s Director of Customer Operations, said: “We apologise to customers affected by delays on the Northern line since Sunday.
“We have identified a fault with the signalling equipment around the Stockwell area that means our service controllers need to manually talk trains through this part of the network.”
Problems on the line started on Sunday evening, with patchy service since then and the line often out of action for entire days. Though some trains appear to be running as of this afternoon, there are consistent station announcements of “severe delays”.
Cause of delays still unknown
The Northern line is the key north-south connection into the City of London, with upwards of 340m journeys taken each year, according to 2022/23 data from TfL.
There have been significant – and disruptive – upgrades to the line in recent years. Back in 2022, the Bank branch of the Northern line was shuttered for four months.
According to TfL, the technical failure had nothing to do with the Amazon Web Services (AWS) outage that knocked much of the internet offline on Monday morning.
Dent added: “Our engineers are working hard to identify and fix the fault, including deploying advanced test equipment, and we will do all we can to restore a good service as soon as possible.
“We are advising customers to allow extra time for their journeys, and to check before they travel using TfL Journey Planner or the TfL Go app.”