Jubilee Line: Fresh disruption after signal failures
Commuters faced severe disruptions on the Jubilee Line after services were hit for a second day running.
A signal failure caused services to be suspended between Willesden Green and London Bridge on Wednesday morning.
The line currently has minor delays. Mayor Boris Johnson said disruptions were "totally unacceptable".
The problems come after hundreds of passengers in five trains were stuck in tunnels for almost an hour on Tuesday evening following a power failure.
London's mayor said: "The problems with the Jubilee Line last night and this morning were totally unacceptable and passengers affected are being refunded.
"A superhuman effort is being made to get the new signalling in, which will mean much more ability to run trains and a huge 33% increase in capacity on the Jubilee Line."
A Transport for London (TfL) spokesman apologised for Wednesday's disruption and said: "This is due to a signal failure at Baker Street and is unrelated to last night's suspension, which was a power supply issue.
"We will be refunding customers affected by this morning's Jubilee Line issues, as we are last night's."
Adding that a new maintenance contractor would take over the line in May, Colin Howard, London Underground's Chief Operations Officer, said: "Obviously we are bitterly disappointed that routine maintenance has ended up causing this major problem last night."
More than 2,000 people had to walk along the tracks on Tuesday after being stranded on one of the hottest days of the year.
Tuesday's disruption began after problems at Canning Town and the entire line was shut shortly after 1900 BST, leaving trains stranded between Kilburn and Canary Wharf.
The power failure issue was resolved overnight, but the Tube line was beset with problems again from 0630 BST.
Rail Maritime and Transport union leader Bob Crow said: "Two weeks ago, the mayor promised Londoners an end to the chaos on the Jubilee Line - last night and this morning we have seen the crisis has actually got worse.
"Last night also showed why we need platform staff to assist passengers in a breakdown situation and it is time for the cuts to those staff to be stopped."
Jenny Jones, from the Green Party on the London Assembly, said: "A lot of the problems on the Jubilee Line are caused because the signalling at the east end of it was botched when it was put in because they wanted it in a hurry for the O2 opening.
"However, last night wasn't about that. It must have been terrifying for those people on the tracks, it sounds horrendous."
Labour's mayoral candidate Ken Livingstone said: "This morning's signalling problems on the Jubilee line, following the chaos last night, just add to the huge frustration felt by Londoners."
Following Tuesday's disruption, he said on Twitter that he was "appalled to hear of tube passengers being forced to walk along tunnels".
The latest disruption has come on the day TfL said it carried a record 1.1 billion passengers over the past year.