The wheels of the last car of a subway train and the track it was running on may have been improperly shaved and polished, possibly contributing to Wednesday's deadly accident, informed sources said Thursday.
The ministry's investigative team has discovered that the Hibiya Line track around the site of the accident in Tokyo was shaved about three months ago, while the wheels of the car were polished some five months ago, the sources said.
Insufficient polishing work or too much shaving could have contributed to the accident, in which the car derailed and plowed into several cars of an oncoming train, killing four people and injuring 35 others, they said.