Transport for London (TfL) is to cut service frequency in half on its London Overground Gospel Oak to Barking line due to continuing problems with new electric trains.
From 18 March, services on the line will operate at 30 minute intervals, rather than 15 minutes, albeit with larger four-car electric trains.
A Class 710 Overground Train at Bombardier's works in Derby
TfL said new Class 710 trains are not yet ready for passenger service but was not able to state when they would be introduced.
New electric trains should have been brought in last spring however manufacturer Bombardier is still experiencing software problems. Meanwhile the last diesel trains being used on the line need to be released for use elsewhere by operator Arriva, resulting in the service being cut.
TfL said it has twice extended the lease on the diesel trains since last summer but they now need to be released.
This means only three four-car electric trains - from elsewhere on the Overground - will be available.
TfL said that by using these trains, overall capacity on the line will remain the same as at the beginning of the year.
Jon Fox, TfL's director of rail and sponsored services, said: 'We are very sorry for the continuing delay to the introduction of the new fleet of electric trains on the Gospel Oak to Barking line and share our customers' frustration.
'The manufacturer continues to solve software issues and we hope that driver training will start in earnest soon, which will bring us an important step closer to introducing the new trains.'
The line has been electrified to accommodate the new trains – a project that itself was significantly delayed.