Between October 3 and 6, 2023, a safety audit was conducted on Tosa Kuroshio Railway Co., Ltd. The audit revealed multiple issues requiring improvement. Specifically, driver-related personnel did not perform temporary driver suitability inspections (attention distribution tests) as mandated by Article 10 of the operational standards management regulations. Additionally, electrical staff did not receive new employee training as specified in the training regulations, and the annual training plans and results were not reported to the General Affairs Manager as required. The company must promptly conduct the overdue inspections and training, and review its training and management systems to ensure proper implementation. Furthermore, the periodic inspection of automatic train stop devices, as stipulated in Article 79 of the safety equipment implementation standards, was not performed despite the Q-values falling below standard. Repairs must be promptly carried out, and maintenance management systems should be improved. Inspections of crossing alarms at Nakakado crossing, including measurement of control section length, were not conducted. These must be performed immediately, and inspection systems should be enhanced to ensure regular and thorough inspections. Lastly, the voltage measurement results of signal lamps at Kubokawa Station were not recorded during routine inspections as required. Records must be maintained accurately, and inspection management systems should be improved. The company is instructed to investigate the root causes of these deficiencies, implement corrective actions, and report the measures taken by January 29, 2024.

The incident involved a train derailment on June 2, 2023, between Tosa-Shirahama Station and Arai River Station on the Nakamura Line, caused by landslides from slopes due to rainfall. Despite prior guidance issued on June 1, 2023, to monitor rainfall and weather conditions and to enforce appropriate operational restrictions, the train was operated at normal speed near the landslide site, resulting in derailment. The site was within a designated regulation zone for slope collapse during rain, but the rain gauge alarm system was not properly monitored. Contributing factors included the train being the last service of the day, the staff being preoccupied with arrangements to cease operations, and the station master responsible for issuing operational restrictions being away from the rain gauge monitoring room. Fortunately, all passengers had disembarked before the incident, but it posed a risk of injury. The company has resumed operations with emergency measures such as slow speed near the site and has been warned to continue thorough safety measures, investigate underlying causes, review operational regulations and systems, and implement permanent slope countermeasures promptly. The company is also instructed to report the measures taken in writing. This guidance was issued by the Shikoku Transport Bureau.