London Overground commuters faced morning rush-hour chaos on Wednesday morning after a signal fault suspended the service between Willesden Junction and Camden Road.
National Rail said several lines were blocked following the broken signal at Hampstead Heath with disruption expected to last until 3pm.
According to TfL, there was no Overground service between Willesden Junction and Camden Road while repairs are carried out.
Severe delays are being reported between Willesden Junction and Richmond/Clapham Junction and Camden Road and Stratford.
Meanwhile a faulty train at Gospel Oak means there is no Overground service between the north London station and Upper Holloway.
