Repaired Tube train derails

Commuter confidence in the Tube suffered another blow today after it was revealed that a modified Central line train undergoing safety testing partially came off the tracks.

The incident, at Hainault, came only 12 hours after another Central line train - also undergoing safety tests - was in collision with a maintenance trolley left beside the lines between Mile End and Stratford stations.

London Underground is today carrying out top-level investigations into both highly embarrassing accidents that will increase passenger fears over safety standards and add fuel to Mayor Ken Livingstone's criticism of those in charge of the Tube.

The Central line, one of the busiest on the system and used by 670,000 people a day, was shut nearly seven weeks ago after a train derailed in the tunnel at Chancery Lane station when a halfton under-carriage motor fell off. Thirty-two people were taken to hospital.

Then it was revealed that there had been three earlier incidents of motors working loose or breaking free, including a derailment of an empty train at Loughton station last September.

Since the Chancery Lane incident on 25 January the line has been closed while engineers carry out safety modifications to the 85-strong train fleet. All bolts holding the motors - there are 32 on each eight-carriage train - have been redesigned and are being replaced. So too are the safety brackets designed to "catch" a motor if the bolts shear but which failed to work at Chancery Lane.

So far LU has modified only about 17 trains and it is these which have been undergoing test running.

An LU spokesman said neither incident had anything to do with the motors or modifications.

Investigators believe the Hainault derailment, which happened early yesterday morning when one set of wheels came off the track when the train was being shunted in a depot, was the result of a track fault. It took more than five hours to get the carriage back on the track.

In the other case, which caused damage-to the front of the train, it is believed maintenance gangs left the trolley too close to the track or failed to secure it properly.

Cynthia Hay, of the passenger watchdog Capital Transport, said: "Commuters will be both alarmed and shaken by this. Confidence in London Underground is already low and it will not be improved by either of these incidents. There will be a lot of people extremely concerned about what exactly is going on."

It was hoped that a very limited Central line passenger train service would begin today. Trains, however, will only run to the east of London and even if they do begin will offer only a token service between either Woodford or Leytonstone and Bethnal Green stations. Trains will not serve the Hainault loop.

Once this initial service is running successfully a further shuttle service will begin to the west of the capital as more trains are modified and complete safety testing.

Bob Bayman, service delivery manager for trains, said it would be another month before the Central line is fully operational with trains running through the middle of London.

Even then they will be subject to strict speed limits and be safety checked every day.

Mr Bayman defended the decision to keep the line closed for so long but he admitted the whole process had "quite clearly taken longer than we would have liked".

He said the problem of both identifying the cause of the motor breaking free and coming up with suitable modifications to the motor mountings had proved to be "far more complex than anyone first imagined it would be. I make no bones about that".

Each train - they are manufactured in two-carriage units which cannot be split - has had to be taken into the workshops and the entire bodywork lifted. This then allows access to the twin axles, holding four wheels, with a motor mounted between.

"We have had to do this to 2,800 motors and it has taken a long time," said Mr Bayman.