Okada: At the same time, there is a feeling of relief, but it is also true that there is still a long way to go. Opening is not a completion of construction, but only a passing point. It is our hope that no trouble will occur after opening.

Inagaki: I realize once again that cooperation can only be achieved with the help of neighbors. Right now, it is the final stage of construction, but I would like to finish the side roads and waterways well for the local community. Maizuru-Wakasa Expressway has been completed and it has become very convenient, so we will proceed with the construction with the utmost care until the opening so that the local people can feel that it was good.

Okada: The river flowing in the area I was in charge of is very beautiful. The water is clear enough to see the riverbed downstream. The local community is very proud of that. Therefore, the construction has been proceeded carefully so that the water in the river is not muddy as much as possible. In particular, areas containing a large amount of strongly weathered granite that are easily washed away by water are likely to collapse. I was going to patrol. Construction at this location has already been completed, and we have taken appropriate measures against flood damage in the future.

At the same time, the construction of Tsuruga Kinakehashi Bridge required attention as much as measures against river water and weathered granite. It is a bridge that straddles the JR Hokuriku Main Line, and is a place where there is a risk of causing a train accident even if one bolt is dropped. In addition, since the power lines are also close, there is a danger that the power lines will be cut if the crane is operated improperly. In such a harsh working environment, each of the construction workers worked on each of the small movements with nervousness.

In addition, I was also in charge of the construction of Tsuruga JCT, which connects to the Hokuriku Expressway that was in operation, but switched lanes four times while ensuring the safety of customers traveling on Hokuriku Expressway. . When switching, it is carried out while performing regulatory work, so a large number of staff are prepared carefully so that they can work together, and there is no effect on vehicles running on the Hokuriku Expressway that passes immediately beside the construction work So great care was taken.

Inagaki: As a result of conducting a soil survey prior to the construction, even if the soil is dug to a depth of 50 m, the water pressure in the soil is so high that water will erupt from it, and it contains a lot of water. I understand that. Therefore, it was judged that general soft ground measures were not sufficient. We decided to introduce new settlement prediction methods and ground improvement methods.

First, we conducted three types of tests as a drainage method for soft ground, and adopted the most effective cardboard drain method *. Next, a vacuum consolidation method is used to quickly and efficiently drain water from the ground. This is a method of forcibly draining water using a vacuum pump. In addition, the latest ground analysis software called "GEOASIA" developed by the Nagoya University Geotechnical Research Group is used. This has enabled us to precisely predict how much ground will subside, and to reduce the amount of embankment in places where there is significant subsidence over a long period of time.
* Cardboard drain method: A number of artificial vertical drains (drain pipes) are installed in soft ground. A method of shortening the drainage distance and promoting consolidation.

Okada: For example, we want to make data from what happened during construction work as much as possible, such as where and how much water flowed during Typhoon 18 in September 2013. In addition, I would like to clearly communicate that there are people who use a lot of water as drinking water in the downstream area of the construction site, and that there is a biotope where fireflies inhabit, etc. I think that such information is necessary for maintenance of the Expressway.

Inagaki: Now, I have detailed data on what I have done as a countermeasure for soft ground. In addition to notifying the employees in charge of maintenance and maintenance, by providing information to the Expressway Research and Development Institute, a common research institute of NEXCO3, it will help in the future construction of Expressway soft ground in Japan and the world. I hope it will be.

Inagaki: Our work is different from making things in factories, but constructing structures in confrontation with nature. Even at the construction of Maizuru-Wakasa Expressway, I myself was informed of natural threats such as abnormal flooding. That is why I want to value nature and the attitude of learning. We will use our experience at Maizuru-Wakasa Expressway to further refine our technology and improve safety.

Okada: We believe it is important to respond flexibly based on the conditions at the site, such as weather and geographical conditions. Even the smallest “awareness” is shared internally and reflected on the actual Expressway. I am working on construction with such awareness. In addition, always try to do what you think best for safety, and take the initiative. Every time I have a chance, I want my subordinates to be aware of this awareness.

Okada and Inagaki: Thank you for the great understanding and cooperation of the neighbors in the construction of Maizuru-Wakasa Expressway. Even after construction is completed, we will continue to make various efforts for safety, including periodic inspections. We look forward to Maizuru-Wakasa Expressway future.