Commuters faced rush-hour disruption this morning with delays on four Tube lines.
A faulty train between Edgware Road and Hammersmith prompted major delays on the Circle line and the Hammersmith & City line.
An update from the lines on twitter said: "Severe delays between Edgware Road and Hammersmith, please continue to use alternative routes to your destinations.
"London Buses accepting valid London Underground tickets via any reasonable route."
An earlier statement said teams were dealing with a faulty train.
TfL said there were also severe delays on the Central Line between Leytonstone and Epping due to a track fault.
Meanwhile there are also delays on the Piccadilly Line, between Acton Town and Uxbridge, due to a signal failure.
Tickets are similarly being accepted on buses via reasonable routes for those affected.
Some passengers took to social media to voice their frustration and ask for updates.
One used the hashtag "poor service" while another said: "I know it’s Monday and no one wants to go to work but unfortunately I kind of do."
