[Press Release] About municipal subway blue line derailment accident investigation report

　We have established an Accident Investigation Committee in Transportation Bureau to analyze the causes of the accident and examine measures to prevent recurrence of the accident.
　We have compiled a report and will announce it.
　On this occasion, we apologize for any inconvenience and inconvenience to the citizens and users again, and based on the discussions at the Accident Investigation Committee, we will work on effective measures to prevent recurrence and strive to regain the trust we have lost.

[Points of Accident Investigation Report (Summary)]

Cause of Accident (Report P.15)
1 Direct cause of derailment
　After the inspection of the embedding device by the authorities' maintenance staff after the commercial operation the day before the accident, one of the three embedding materials, which were part of the equipment, was still fixed on the main line rail, The train wheels got on the embedding material.
2 Background of the trolling material being fixed on the main line rail
　Of the three working teams, the staff who inspected the appropriate trolling material completed the inspection while fixing it on the main line rail, and inserted the chain lock device pin (warning, buzzer, etc. stopped).
　After that, it was judged that the work was completed by turning off the alarm, stopping the buzzer, etc., and it was not confirmed that the transceiver body was in its original storage position.

Analysis of Cause of Accidents (Report P.16)
1 A lack of understanding and awareness of the work implementer's work content and regulations.
2 The work procedure and the final confirmation method were not clear.
3. The division of roles in the work was not functioning.
The four organizations have not been able to understand this situation.

Measures to Prevent Recurrence (Report P. 20)
1 Efforts implemented urgently
　Implement measures to prevent recurrence in order to solve problems in the trolley device and urgent efforts to ensure safe operation.
(1)　Create a procedure manual for inspection of the transceiver, clarify work procedures and clarify the role of the person in charge of work.
(2)　Clarification of final confirmation methods, such as creating a check sheet for handling of transceiver devices
(3)　Re-thorough compliance with the rules, such as notification to all staff
2 Measures to be implemented in the future
(1)　Implementing regulations and strengthening management
(2)　Fundamental review of staff education
(3)　Creating a system for quickly collecting and sharing safety-related information
(4)　Efforts to further improve the safety of transceiver devices
3 Reform of the organizational culture for “unrelaxing safety”

The full text of the survey report is posted on the Transportation Bureau website along with information related to the accident.
https://translate-en.city.yokohama.lg.jp/kotsu/kigyo/anzen/blueaccident.html