Commuters face travel misery tonight after two platforms at Waterloo were closed ahead of the evening rush hour.
Signalling problems at the station affected services on platforms one to four this afternoon, with platforms three and four later closed completely until the end of service today.
The closure means some South West Trains services have been cancelled, while others were delayed or revised at short notice.
Some services were also beginning at destinations further along the line to help reduce congestion at Waterloo.
Journeys which usually stop at Vauxhall, Clapham Junction, Earlsfield and Wimbledon were among those affected.
Engineers investigated the signal problems this afternoon but the nature of the fault can only be rectified once the last trains have departed from Waterloo, South West Trains said.
Customers travelling from Waterloo or stations on the South West Trains line were urged to check display boards and listen for announcements at stations to see how their journey may be affected.
Live travel information is also available on the South West Trains website.
