A power outage on the JR Utsunomiya Line affected about 190,000 people due to multiple human errors linked to the mishandling of trolley wire replacements and oversight of wear in inspection images.
On the 17th, JR East announced the results of an investigation into a power outage incident on the JR Utsunomiya Line that affected approximately 190,000 passengers. The investigation revealed that multiple human errors were responsible, including the incorrect exchange location of the trolley wire and the failure to notice inspection images indicating wear. These mistakes occurred during a switch from visual inspections by workers to equipment-based monitoring.
The incident took place late at night on the 8th near Furukawa Station in Ibaraki Prefecture, when the trolley wire, which supplies electricity to trains, snapped. The diameter of a new trolley wire is 15.3 mm, and it is supposed to be replaced when its diameter falls below 8.7 mm, but the snapped wire had worn down to just 4.1 mm. Furthermore, during a visual inspection in April 2023, it was confirmed that the wire had worn to a diameter of 7.9 mm. Although it was supposed to be replaced three weeks later, workers mistakenly replaced a parallel trolley wire instead.
JR East plans to improve its monitoring systems starting April 2024, introducing image analysis by measurement vehicles to determine wear levels of the trolley wires automatically. They expressed intentions to ensure that images showing clear signs of wear are verified multiple times to prevent future oversights. Since January, similar electrical issues have been reported across several JR lines in the Tokyo metropolitan area, with human errors being identified as the cause in previous problems as well, prompting an apology from the president of JR East, Yoichi Kise, who stated that this situation directly impacts the core of the company's operations.
