East Japan Railway has now resumed normal operations on its Tohoku Shinkansen line. Some services had been canceled after two connected trains came undone last week.



The line includes trains that are coupled for part of the route, before separating and heading to different cities in northeastern Japan. But travelers have had to get off and switch trains since the incident.



The company resumed some coupled services on Friday, and returned to its normal schedule on Saturday.



A coupled train was travelling north from Tokyo on March 6 when it separated. The railway company says it took emergency measures to confirm safety and is now investigating the cause of the incident.



There was a similar case last September. The likely cause was identified as a metal fragment triggering an emergency decoupling switch.