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Shiraishi providing the foundations for Japan’s infrastructure

Interview - June 1, 2022

Have a safe and reliable infrastructure is crucial for a successful society, however when natural disasters such as earthquakes or typhoons are commonplace, this necessity is only exemplified. Oriental Shiraishi has been providing prestressed concrete and pneumatic cassions for used in the construction of public infrastrcutre such as highways and bridges. In this interview, President Tatsuya Ohno discusses Oriental Shiraishi’s unique technologies, what must be done to protect Japan’s infrastructure from natural disasters and how this can be implemented in other disaster prone nations.


Japan’s construction boom occurred more than 50 years ago and as such, a lot of infrastructure is now aging and in need of maintenance, repair, and upkeep. We know that cities such as Tokyo and Osaka still continue to grow but this will level off by 2040 as Japan’s population continues to decline. What is your assessment of Japan's infrastructure and construction industry currently? What needs do you foresee in the future?

Climate change has significantly been affecting Japan. I am from Hiroshima prefecture and the temperature used to be very moderate and it was comfortable to live in. When I was a child, I didn't have much experience with disasters that involved winds or floods. But the situation now is totally different and we have been hearing a lot in the news about typhoons, landslides, and other disasters. Climate change is affecting Japan at an unprecedented level. We need to be prepared for this in advance. Of course we have lots of earthquakes that have happened in the Tohoku region. The Nankai Trough Earthquake will come within 30 years according to information and we also need to be prepared for this to protect human life, assets and also the Japanese economy. Therefore, we need to make investment in infrastructure.

It has been mentioned that the Japanese construction business has matured as a market, and a number of road networks have been developed over time in Japan, but it seems that there are still many two-way single lane roads. At times, the accumulated snow shuts down the road for the traffic. The lane closure at two-way single road due to construction work of repair and reinforcement for aged infrastructure have a big affect to traffic, distribution, economy and tourist industry.    

Compared to South Korea, North America, and other areas in the world, the road network in Japan isn’t fully developed yet.

It is also important to connect missing links. If the missing links are eliminated, it can improve the efficiency of road traffic. In addition to what I said before about traffic problems due to the small number of lanes of road networks that are sometimes closed due to the accumulated snow in winter, we are trying to increase the number of lanes to four or six to eliminate these issues. Having a dual road network is also important. Since Japan experiences numerous earthquakes in order for disaster recovery and disaster area support it is important to develop dual road network.

To start rescue work quickly at the disaster area it is needed to utilize another road to reach the affected areas due to the disaster.

We are also trying to develop and maintain expressways.

You also mentioned that Japanese infrastructure has started to age over time, of course we need to take countermeasures to fix these as well. We also need to repair and reinforce them when they get damaged, but we think that we need to do this in advance before the damages occur and exert efforts to keep usable for a longer time in the future. We provide our technology such as Prestressed Concrete as well as Pneumatic Caissons for development of road network and four-lane and six-lane road, elimination of missing links, repair and reinforcement of bridges, and hydraulic control measures for heavy rainstorm.


You mentioned that there is a need to pre-empt these disasters and you need to do something about these aging infrastructure now rather than reacting too late. We know that Japan is located at the intersection of three tectonic plates; there are many earthquakes, landslides, and natural disasters to consider. Your company has come up with some technologies to prevent help in this respect. Can you tell us more about this method and the other technologies you are using to prevent such disasters taking place?

The PCR Method is a non-open cut method to construct underpass and/or tunnels without disturbing the existing railway crossing operations or traffic circulation. We use a prestressed concrete girder to push in and create a certain shape and we dig the soil surrounded by the prestressed concrete girder from the ground. By doing this, we are able to create roads or pathways using this technology and while working, we do not interfere with any traffic on the road or railways. In addition to that, even though we have a shallow clearance of soil beneath the road or railway, we can still utilize this method.

Prestressed Concrete Girder construction site

For the Lowering Method, we construct two concrete arch pillars at the each end of the bridge, lower them down and connect them at the centre of the bridge to make arch ring of the bridge. Even if the ground is a very deep valley, we can still utilize this method to create a bridge economically and safe.

Lowering Method Construction Site>

With the NAPP method we utilize or leverage the strong tension force by introducing tension to a hollow steel rod and connected it to screw placed inside. At the project site, the concrete member with NAPP method is placed inside the structure in advance and the tension is transmitted to the concrete member by loosening the screw after concrete is placed in situ and harden. 

The advantage of the NAPP method is being able to prestress without using heavy equipment such as the pump.

With regards to CFCC slab, we add prestress with carbon fiber cables to achieve high durability without using corroded materials such as steel or rebar.

Next, let me talk about Bi-Prestressing Construction Method. This method is to increase the strength and efficiency by adding more tension to the compressed side of prestressed concrete members which is added compressed force at tension side, which is a weak point of it. It is called Bi-Prestressing Construction Method because it adds prestress at the upper, middle and lower side of the concrete member. This can be applied to the structure of the bridges with longer spans and the structures with lower height of the concrete members.


We know that your company is employing digital technologies such as the SCBR (Smart Connected Bridge) Method and the SLJ Slab method. Can you tell us more about these digital technologies and how they are helping to increase the efficiency at the work sites?

In Japan, it is necessary to increase productivity at the project site due to decreasing birth rates and the aging population. It is required to develop the technologies to construct with less time and manpower.

SCBR method, SLJ slab method and precast concrete members (factory fabricated concrete product) can realize increases in productivity, safety at the project site, less manpower and shorten the construction period. Furthermore, those methods bring efficiency at the project site have simple assembly of the concrete members.

We believe that digital transformation at project sites is also important to increase productivity.

We promote digital transformation through three functions such as “Efficient management work”, “Efficient construction work”, and “Improvement of construction work management”.

We are developing and applying an automation system of management work, automated construction work of the Pneumatic Caisson method, measurement work of damaged parts of concrete members by Artificial Intelligence, an automated drawing system, and a concrete placement management system using Augmented Reality, jointly researched with  universities, public research institutions, and companies in the same field.

When our productivity is increased and working hours are reduced at project sites, I would like our employees to have extra time for their hobbies or self-improvement.

Due to the decreasing birth-rate and aging population in Japan, the construction industry needs to be attractive for young people to enter the construction business. Digitalization and remote control or automation work with IT can attract young people. We hope that the youth would think that the construction industry is interesting enough for them to work with us. We would like to continue our development of technologies to do so. For example, when it comes to Pneumatic Caissons, we adopted remote operations where our workers do not have to go inside the operating space. Furthermore, we are working on the development of the excavation work based on algorithms for actual use. When it comes to prestressed concrete, we utilize digital tools to automatically put tensile forces or grout and also we use that to simulate or somehow extrapolate hollow space about the damaged parts through AI.


In terms of carbon neutrality, the production of concrete has a huge environmental burden. Many companies are moving towards greener versions of concrete, for example, we met Aizawa, a company in Sapporo, which created self-healing concrete that uses carbon fiber composites to reduce the level of environmental burden. Can you tell us more about the concrete types you are adopting and how you are becoming a carbon neutral company?

I would like to briefly explain what we have been doing at the moment for prestressed concrete, which is our main product. Due to its high durability, I think we could contribute to a longer period for scrap and build. We strongly promote to our clients to apply CFCC slabs, which we developed. Carbon fiber composites are highly durable materials of concrete.

We are also utilizing blast furnace slag and fly ash which are alternatives to the conventional concrete as part of our efforts to reduce CO2 emissions. At the moment, we are engaged in research and development about geo-polymer concrete which does not include cement. Also, we are researching the technologies of CO2 absorption to concrete and incorporate CO2 into hardened concrete for the practical applications of concrete. We are trying to get some good results from these ongoing research activities that I mentioned above hoping that we could apply to our prestressed concrete or concrete materials for maintenance, repair, or reinforcement of infrastructure.

Towards the year of 2030 or 2050, we think it is important for us to increase the proportion or percentage of renewable energy that we use in the field, in our plant, and office spaces. Also we believe that it is important to collaborate the research and development with manufacturers of cement and steel.


Can you tell us more about your co-creation with foreign partners? Looking towards the future, what kind of new partners will you be seeking?

In the past, we have done a lot of our business overseas but we decided to withdraw from international business considering the various risks. We are considering to enter it again with potential partners in the future.

At the moment, we have been working on large scale of rehabilitation of expressways in Japan. We were asked to repaint the old metal girder. Sometimes old coating include lead, a hazardous material. We remove the old coating by adding heat on the surface with induction heating machine efficiently and safely.

We are the one of the sales distributors in Japan of the Norwegian company which sell the IH coating removal machine. We are promoting the IH coating removal machine and coating removal work through advertisement, work demonstration and training.

In the past, we have consulted the company to research, design and study to implement the Pneumatic Caisson method to adopt the method to a waste water facility project in Southeast Asian country. We still have some communications with this company for market surveys or research. We will try to continue this kind of relationship with them in the future.

When Japanese contractors try to apply the Pneumatic Caisson method to their projects, we may take part in their project, provide technical instructions, technical cooperation, or lease the Pneumatic Caisson equipment. We consider that this kind of participation may develop our international business. We have a technology that reinforces the superstructure and foundation of bridges as well as one that provides anti-earthquake reinforcements. We are thinking of having domestic partners to work together in order to adopt our anti-earthquake technologies to the countries which suffer from seismic activity.


Your Pneumatic Caisson Method is one of your signature technologies and it functions similarly to a cup and water - the cup disperses water and it creates an air gap. Japan has a very complex soil and is subject to earthquakes frequently, and this requires specialists solutions. There are countries around the Pacific Rim of Fire such as Malaysia, Indonesia, Chile, Mexico, and even California which are also subject to tectonic activities. Which countries do you foresee that your technologies will be utilized?

The Pneumatic Caisson method is to excavate the soil inside the working space at the bottom of the structure, supplying air into the space to push down the underground water and sink the structure itself. The Pneumatic Caisson has a strong anti-seismic structure and can adapt to soft ground with high underground water. I think Japan has been utilizing this kind of structure due to lots of underground water.  This implies that countries having a similar structure will possibly be utilizing our technologies. Countries that have a lot of rivers, ports, and coastal areas are other options as well as in terms of building bridges. To be more specific, Southeast Asian countries would be the first option that we could think about.

As I mentioned above, we had past experiences of doing business internationally but we decided to withdraw. From our experience, we need to seriously take into consideration the risks we need to take. We need to find a partner with an existing international network or business experience in foreign countries. If we are able to find this kind of partner, I believe we will be able to mitigate the potential risks.

We would like to develop our future overseas business through collaboration with potential partners like our old overseas projects such as installation of monorail girders in Dubai, installation of rail slabs for the Taiwan express train or construction of bridge foundations in Vietnam. Also we hope that we can adapt our repair and reinforcement technologies for our future overseas projects.

Pneumatic Caissons construction site

This year your company is celebrating its 70th anniversary. Imagine we come back in five years and have this interview again: what would you like to tell us? What are your dreams for this company and what goals would you like to have achieved by then?

At the moment we are trying to strive to increase our revenue or sales. But we also would like to put importance on quality, not only on quantity. Japan faces a number of disasters due to its geology and aging infrastructure. Because of this, we would like to provide solutions through the kind of infrastructure that we provide. We developed the technologies that I mentioned above in order for us to provide solutions to the challenges that Japan is facing. Five years from now, we would like to be in a position where we are able to provide solutions continuously through our R&D efforts. For international business, we hope that we can start again somehow with our technologies. I would like to believe that our employees have been proud of our company’s business and for what they have been doing. I hope that they are highly motivated now and will be more motivated with a strong mission five years from now. Lastly, I also look forward to meeting you again for another interview five years later.