Facing a formidable task

The Tateiwa Tunnel is one of the tunnels to be constructed between Shin-Hakodate-Hokuto Station and Sapporo Station on the Hokkaido Shinkansen line, scheduled for completion by the end of FY2030. Obayashi is in charge of the Yamazaki section, which covers 4.96 km of the 17 km tunnel. The tunnel is being excavated by NATM (New Austrian Tunneling Method) in which concrete is sprayed to the excavated area and rock bolts are placed to secure it to the bedrock.

This is a typical method for tunnels, but that does not automatically make the construction easy. At this site, the geological conditions are extremely variable, and the tunnel passes directly under a river in two places. Therefore, a detailed geological survey and support design based on the survey results are carried out, and when necessary, auxiliary construction methods are applied to ensure safety before excavation. This delicate site requires high level of expertise and technical ability.

Expertise and Experience to Utilize Technology

Surveying is one of the major factors in the construction of tunnels. Not only is it important for the quality of the tunnel and work safety, but it is also essential in connecting tunnels of different sites where not even the slightest deviation is allowed at every step of the process. Although surveying technology has improved dramatically, it is crucial to repeat the surveying process to verify results and minimize any errors.

Currently, AI and other technologies play an increasingly important role in construction sites by improving safety and work efficiency. They include detection systems with alarm and automatic stop devices to keep heavy machines at a safe distance from workers and traffic signal system that detect vehicles and control traffic in tunnels.

Obayashi proactively incorporates these advanced technologies into its construction sites. But it does not mean that we rely entirely on machines and technologies. No matter how advanced the technology, it is the people who make the most of it. Especially in the field of tunnels which bear many uncertainties, expertise, experience and judgment are indispensable in maximizing the true value of technology.

The Future

At our construction site, many young workers are learning the techniques from veteran skilled workers.
In the past, tunnel works usually meant building new tunnels. But after Japan’s high economic growth period, what is needed now is the maintenance and repair of the tunnels as evidenced by the increasing need for large-scale renewal projects. As tunnel works enter a new phase, Obayashi’s great asset will be the combination of skilled workers’ expertise accumulated over many years and younger workers’ ability to utilize new technologies.

Breaking Through the Tateiwa Tunnel

I have been engaged in tunnel construction for 23 years, but no two tunnels are alike in environment or conditions, and every moment is a constant struggle with nature, requiring an appropriate response to ever-changing situations. As an engineer, I feel that applying all my knowledge and skills to overcome difficulties in tunnel construction is challenging but rewarding. I must admit I am anxious during the construction process. That is all the more reason to work hard at it. So, it’s not easy to describe in one word how I feel when a tunnel is safely cleared.
I hope that the completion ceremony of the Tateiwa Tunnel will be held with smiles from the engineers and workers who are like my family and with whom I spend days and nights. Imagining the bullet train running to Sapporo, I will keep working on each and every process faithfully with attention to detail.