This is seven months later than originally planned because the line was damaged during the devastating earthquake in northeastern Japan in March.

Atacs is a radio-based train control system with similar functions to those of communications-based train control (CBTC) and Level 3 of the European Train Control System (ETCS). Atacs does not require track circuits to locate trains but uses a system whereby trains recognise their own position. "If the Senseki Line had had a traditional system needing more ground facilities it would have been difficult to start operation this early," says JR East.

The Senseki Line is used by about 200 trains a day running at five-minute headways.

JR East plans to introduce Atacs on other high-density commuter lines such as those in Tokyo. More functions will be added to Atacs in the future to allow it to control level crossings and to reduce train speed during heavy rain or strong wind.