By AYATERU HOSOZAWA/ Staff Writer
March 12, 2025 at 16:34 JST
The decoupled Hayabusa and Komachi trains in Tokyo’s Arakawa Ward on March 6 (Yasumasa Kikuchi)
East Japan Railway Co. announced on March 11 the resumption of coupled operations for the Tohoku Shinkansen, following a suspension of service after two trains unexpectedly decoupled mid-journey in Tokyo.
Multiple-unit operations will resume starting with Tokyo-bound trains on March 14, connecting with the Akita and Yamagata Shinkansen lines, with a full return to the normal schedule expected the following day.
The incident occurred on March 6 when the coupler connecting the two units of the Hayabusa-Komachi No. 21 train, bound for Shin-Aomori and Akita stations, disengaged while passing through Tokyo.
The incident caused significant disruption to bullet train services with a total of 111 trains being canceled that day, affecting more than 150,000 passengers.
JR East's investigation revealed that repeated electrical signals were being sent to unlock the coupler. To prevent a recurrence, the company will implement temporary safeguards while continuing to investigate the root cause of the malfunction.
Following the incident, an inspection of the Komachi train found that the lever designed to unlock the coupler was repeatedly malfunctioning.
It is believed that multiple electrical signals were accidentally sent to the cylinder that controls the lever's movement. JR East stated that there have been no similar incidents in the past, and the fundamental cause of the malfunction remains unknown.
As a temporary measure, the railway operator has created metal parts to physically lock the air compressor that powers the cylinder, preventing it from functioning even if electrical signals are sent.
These metal parts will soon be installed when trains are coupled at Fukushima and Morioka stations.
“We have confirmed the strength and effectiveness of the metal parts,” said Hirohiko Ikeda, JR East director-general of the Shinkansen general management department. “We will continue to investigate the cause of the incident and implement permanent solutions to prevent a recurrence.”
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