East Japan Railway says it has determined a possible cause for the disconnection of two linked Shinkansen trains while they were moving at high speed, after finding metal fragments around an emergency switch.
A coupler on the Tokyo-bound two train service on the Tohoku Shinkansen line became unhinged while the train was running between Furukawa and Sendai stations in Miyagi prefecture on September 19th.
A braking system was automatically triggered, forcing the two connected trains, the Hayabusa and Komachi, to come to an emergency stop. None of the cars derailed and no one was injured.
It was the first incident in which moving Shinkansen trains became uncoupled.
The railway company, also known as JR East, says that it has inspected the trains and found a number of metal fragments around the emergency switch designed to disconnect the coupling component installed on the side of Komachi. The metal pieces were from several millimeters to about two centimeters in size.
The company suspects that the metal fragments may have come into contact with the terminal of the switch, activating the disconnecting function and causing the coupler to come off, while the trains were moving.
The metal pieces are believed to have been there since the train was manufactured.
JR East also says that it has checked around the switches on all 96 Shinkansen trains, and found similar metal fragments on 10 Komachi trains, which were then removed.
The operator says it will remove the wiring in the switches on all 96 Shinkansen trains by the end of October and discontinue their usage as there are other devices that have the same function.
A senior JR East official, Ikeda Hirohiko, says that he and his company once again deeply apologize for causing concerns about the safety of the Shinkansen system.