Chuo and Sobu Lines (Local) in Tokyo have been frequently disrupted by sudden drivers' illnesses for nearly four years. Several investigations have been conducted, but the cause remains unknown. In spite of safety prayers by a Shinto clergy, there is no sign of improvement. The so-called "Nakano depot disease" has had negative impacts both on passengers and train crews.
The Chuo and Sobu Lines (Local) is a commuter railway in Tokyo that consists of two lines, Chuo Main Line and Sobu Main Line. They connect Chiba and Mitaka stations, calling at all stations including small ones. They are 60.2 km (37.4 miles) long, and trains formed of ten coaches run every two minutes at peak times.
Tokyo Shimbunreported in 2024 that there have been 40 train disruptions in the past three years as drivers suddenly feeling unwell. Drivers in their 20s to 40s suffered from dizziness, anaemia, drowsiness and stomach aches, resulting in overshooting platforms or partial service suspension lasting 20 to 30 minutes. All of them had no trouble during a daily health check before getting onto a train. There are less than three such cases a year on other lines, but the Chuo and Sobu Lines (Local) apparently have had far more troubles than others.
According to Nippon Cultural Broadcasting, trade unions insisted that the issue were triggered by overworking, but JR East dismissed the claim as no such troubles had been observed on other busy lines such as Yamanote Line. The train operator conducted various investigations including air and water testing at Nakano depot, where drivers and crews gather every day, but no abnormality has been observed. The company even relied on religion, asking a Shinto clergy (kannushi) to pray for safety as well as health, but the situation remains unchanged, as Asahi Shimbun reported.
The government acknowledged the "Nakano depot disease" in response to an enquiry submitted last month by an MP. However, the Ministry of Land, Infrastructure, Transport and Tourism has refused to intervene in the cases at the moment, insisting that JR East should take responsibilities for its employees.
The unreliability of the Chuo and Sobu Lines (Local) is certainly a matter of concern. Trade unions have urged JR East to significantly improve the tight work shifts and replace old facilities with new ones, and the company has accepted some of their demands, but the problem is yet to be solved. Unless the troubles subside, there might be calls for the government to take action. However, it is hard to imagine what measures could the authorities adopt in addition to what the train operator has already done.
