London Underground: Investigation into Metropolitan line wheel faults

TfL ran a special timetable on the Metropolitan line for weeks

A formal investigation has been launched by Transport for London (TfL) after an issue with wheels on Tube trains forced the entire Metropolitan line fleet to be checked over.

In April, urgent safety checks were carried out after engineers identified a fault with some of the wheels.

Due to the safety concerns a special timetable was put in place until the problems were fixed, with some services having to be run every 30 minutes.

TfL resumed a normal service on 9 May.

Last week at Mayor's Question Time, Conservative London Assembly member Susan Hall asked London Mayor Sadiq Khan whether the delays had been caused by "the wrong calibration of lathes" making the wheels too small to run.

Remedial works

Replying four days later Mr Khan said that was not the case but confirmed an investigation was under way.

He said: "Routine checks to the Metropolitan line fleet identified an issue with some wheelsets on the trains.

"The wheels identified were not too small to run on the tracks, but presented issues which meant the affected trains had to be removed from service whilst remedial works were carried out.

"The root cause of the issues identified will be subject to a formal investigation."

Trains had to be operated between Baker Street and Amersham or Chesham every 30 minutes, between Watford and Baker Street every 15 minutes, and between Uxbridge and Aldgate every 15 minutes.

Services are now running as normal:

• Uxbridge - Baker Street: Every five to 10 minutes

• Watford - Baker Street: Every six to 10 minutes

• Two trains every hour to and from Amersham

• Two trains every hour to and from Chesham

Follow BBC London on Facebook, Twitter and Instagram. Send your story ideas to [e-mail]