The Docklands Light Railway (DLR) has been hit with speed restrictions after engineers warned trains were going too fast on some sections of track.
A routine review of the signalling system uncovered the problem with TfL slowing most sections by 5kmph.
Posters have also been placed outside stations, explaining to passengers that "some small reductions in train speeds on sections of the DLR network have been implemented as part of ongoing review of DLR's signalling system".
TfL’s general manager for the DLR, Tom Page said the trains had not exceeded existing speed limits but passenger safety must come first.
He added: "Following a review of our signalling system we identified a pre-existing technical issue, which meant there were a number of places where there is not enough margin between maximum recommended speed and the speed of the trains.
"For the continued safe operation of the network, we decided to reduce the speed at these locations.
"The DLR continues to be one of the safest light rail networks in the country."
TfL admitted the slower speeds would affect the usual service and frequencies.
The DLR is an automated system although it does have train captains on board the trains.
New trains were due to be introduced in April but have been delayed.
The direct Stratford to Lewisham service has also been suspended and no decision has been made on whether these changes will be made permanent.
TfL has apologised to passengers for any disruption has said it is looking at ways to minimise any impact.
