Coupled shinkansen bullet trains returned to full service in northeastern Japan on Saturday morning, the operator said, following an incident earlier this month in which cars separated while in motion.The move marked the return of normal operations on the Tohoku, Yamagata and Akita shinkansen lines. On Friday, JR East said safety checks were completed after the incident on March 6 that affected many travelers.JR East, the only operator that connects different types of shinkansen, had a similar case in September 2024. It said metal fittings will be used to secure coupling levers in drivers' …READ FULL ARTICLE