Rail passengers have issued a “crisis bulletin” warning of the “impending collapse” of the Gospel Oak to Barking Overground line due to its trains all being removed.

Transport chiefs are scrambling to find spare trains to run on the problem-ravaged line before all of its existing ones are transferred at the end of their lease.

Two of the eight have already been sent to West Midlands Trains and another is set to go this month. As it stands, by April there will be no trains left on the line.

The Barking to Gospel Oak Rail User Group (BGORUG) says in mere “days” there won’t be enough trains to operate the six-train weekday timetable and are demanding Sadiq Khan steps in.

Secretary Glenn Wallis said: “This crisis has been developing for a year, but it was less than a month ago that TfL took the first effective action to try to head off the impending collapse of the service and as usual for TfL, it was far too little, far too late.”

TfL, Network Rail and Bombardier have perfectly demonstrated how not to upgrade a train line since announcing electrification works almost three years ago.

During the eight-month closure to install overhead wires from June 2016 to February 2017 a gaffe by Network Rail meant the wires were “incorrectly designed”, while other materials were delivered late.

The line closed for another two months at the end of 2017, before opening in January 2018 ready for the new trains.

Except, Network Rail didn’t finish safety checks on the new line until June last year, and a new launch time of “summer” 2018 was given because the new four-car Bombardier built trains needed “further software development”.

That software still doesn’t work, and no one knows when it will. Once it does, drivers will need to be trained.

As a result of the loss of two trains already, there is a reduced peak service with delays, cancellations and overcrowding common. Since November the weekend service has been cut.

Network Rail and TfL are effectively blaming each other for the delay, and the Barking to Gospel Oak Rail User Group (BGORUG) has accused TfL of doing nothing.

TfL’s Overground chief Rory O’Neill said: “We are sorry for the continuing delay to the introduction of the new fleet of trains on the Gospel Oak to Barking line. The manufacturer, Bombardier Transportation, have advised that they need more time for software development.

“We share our customers’ frustration and continue to push Bombardier to do everything they can to allow us to bring the new electric trains into service as soon as possible.

“Given the continuing delays we are now exploring the option of modifying other electric trains for temporary use on the line.

“We are testing a modified train on the line and expect to make a decision on whether it is possible to operate it later this month. It would operate alongside the existing diesel trains.”