Engineers are struggling to identify the cause of a signalling fault on the London Underground's Northern line that has caused severe delays since Sunday. Transport for London (TfL) has said the issue, located in the Stockwell area, is unprecedented and may persist into next week. The disruption has led to overcrowding, station closures, and passengers being unable to board trains.
TfL is considering cancelling the weekend night tube service to allow for more extensive investigations if the fault is not resolved on Thursday night. The signalling system is wired, ruling out a cyber-attack like the one experienced a year ago, and deliberate sabotage has been dismissed due to the fault's location.
The Northern line, previously dubbed the “misery line,” has been reliable since upgraded signalling was introduced over a decade ago. This week's problems have forced controllers to manually guide drivers through the affected section, slowing journeys across all branches. A separate signal failure at Tooting on Tuesday was repaired the same day.
Passengers are advised to avoid the Northern line where possible and to use alternative routes. London bus services are also affected due to increased road traffic and diverted tube passengers. TfL has apologised and is deploying advanced test equipment to fix the fault.
Meanwhile, London Underground has offered unions a three-year pay deal based on the retail prices index, which Aslef has formally recommended. The RMT union has not yet responded, suggesting industrial action may be avoided for now.
