Tokyu Den-en-toshi Line collision resulted from a decade-old error

A train collision occurred on the Tokyu Den-en-toshi Line when a returning train, stopped by a safety system, was hit by an inbound train. The returning train stopped short of its destination due to an Over Run Protector activating, causing its rear to protrude onto the main line where it was struck by an inbound train. The incident caused significant service disruptions, impacting over 650,000 passengers and leading to numerous train cancellations.