Enhance safety measures for linear line construction after fatal accident

A tunnel collapse accident occurred in which one worker was killed and another was seriously injured during the construction of the Linear Chuo Shinkansen line. Unprecedentedly difficult construction work lies ahead. Central Japan Railway Co. (JR Tokai) needs to investigate the cause of the accident and do its utmost to prevent a recurrence.

The accident occurred at a construction site for a work tunnel in Nakatsugawa, Gifu Prefecture, when part of the bedrock collapsed following blasting work. It was the first fatal accident to occur in the construction of the linear line.

JR Tokai temporarily suspended tunnel construction work in mountainous areas to ensure safety at each site. The prefectural police are investigating the situation at the time of the accident, with an eye toward possibly establishing a case on suspicion of professional negligence resulting in death and injury. Whether there were any flaws in the work procedures and safety management must be clarified.

Of the 286-kilometer Shinagawa-Nagoya section planned for advance opening, 86% is tunnel sections. Construction began in 2015 and is underway at a number of sites.

Trial digging has also begun at locations deeper than 40 meters below the surface, which is termed “deep underground.” A total of 33 kilometers from Shinagawa and 17 kilometers in Aichi Prefecture will be deep underground construction.

With approval from the land, infrastructure, transport and tourism minister or the governor, construction work deep underground in the metropolitan areas centering in Tokyo, Osaka and Nagoya can be carried out without the consent of landowners on the ground. Until now, it has been believed that the deeper one goes, the harder the ground gets, and the effect of construction work deep underground on the surface of the Earth is small.

Last year, however, sinkholes occurred in city roads in Chofu, Tokyo, due to deep construction work on the Tokyo-Gaikan Expressway. Many residents are concerned about land subsidence and other matters where the linear line is being constructed.

It is important for JR Tokai to thoroughly examine the effects on things like buildings on the surface of the ground and to verify the safety.

In addition to urban areas, extremely difficult construction works will continue in other places, including drilling 1,400 meters underground in the Southern Japanese Alps. Once an accident occurs, the construction period is delayed. Safety measures must be checked again.

The linear line is a huge national project, with the construction cost totaling ¥9 trillion. The three major metropolitan areas of Tokyo, Nagoya and Osaka will be connected in just over an hour, and the acceleration of the flow of people and goods is expected to have a significant economic effect.

However, the Shizuoka prefectural government has refused to allow the construction of tunnels in the prefecture, citing the impact on the water volume of the Oi River, among other factors. The initially planned opening in 2027 will inevitably be postponed.

An expert panel is examining the impact on the Oi River. Based on the examination, it is important for JR Tokai to explain the matter carefully to residents. It must not be forgotten that safety and public understanding are essential to the success of the project.

— The original Japanese article appeared in The Yomiuri Shimbun on Nov. 8, 2021.