After a Tunnel Construction Triumph in Japan, All Eyes Are on CIM (not BIM)
What’s CIM? For the unfamiliar, Construction Information Modeling/Management is a localized term used in Japan’s construction industry in place of BIM (Building Information Modeling). The Mikusa Tunnel project on Japan’s Kinki Highway Kisei Line was the first of many projects to use it for the entire building process. The Obayashi Corporation comprehensively used 3D models to build the tunnel, another first in Japan, earning it the country’s first AEC Excellence Award in 2017.
“The Mikusa Tunnel’s construction itself is not really different from any other tunnel,” says Shinya Sugiura, section chief of advanced technology planning in Obayashi’s Civil Engineering Production Technology Group. “The key differences lie in the process.” That process upped the ante on using digital methods and new materials, including the excavation surface prediction used for tunneling navigation and building with enhanced, more durable concrete.
As his country has been slow to incorporate CIM, Sugiura consults with overseas companies with extensive BIM experience to share information and gain insight. “While the term is different, we’re working on the same principles,” Sugiura says. “We agree BIM/CIM is the way to go for the construction industry and don’t understand why all constructors aren’t using it.”
Japan’s Ministry of Land, Infrastructure, Transport, and Tourism began promoting CIM in 2012. As Obayashi completed construction of the Mikusa Tunnel using 3D models, measurements related to tunnel excavation, such as displacement, groundwater level, terrain, and geological information were continually input as work progressed, and that data was shared instantly with the company’s headquarters using the cloud.
“Civil and infrastructure engineering requires an understanding of the geology and terrain of a construction site,” Sugiura says. “For tunnels, we need to be able to anticipate what kind of rock or earth we will be excavating as construction proceeds. It is important to consider measurements taken on-site, the surrounding groundwater levels, and images of the site for planning future phases of construction. Tunnels are especially complex projects with a lot to consider beyond the structure itself.”
Sugiura’s previous work with Obayashi’s civil engineering projects relied largely upon traditional skill sets. Civil engineers were required to read drawings of floor plans, sections, and elevation plans, but many of them did not have experience working with 3D models.
But for large infrastructure projects like the tunnel, more than 500 people can be working on-site, including subcontractors. “It became apparent that 3D models and other digital tools, when used alongside conventional communication methods, could improve the flow of information on the ground,” Sugiura says. Until recently, the software tended to be difficult to use and expensive, and its output couldn’t keep up with the pace of the projects.
However, as both the software and the hardware needed to run it improved by leaps and bounds, the process became more accessible. “Soon we were able to easily prepare presentations of our plans that used 3D models,” Sugiura says. The company started using these tools on location at several sites, where they had previously used diagrams illustrating each step of the construction process.
Using 3D models that could be viewed from any angle made it much easier to visualize and understand the work at hand. “The initial feedback we received was overwhelmingly positive, with many asking to use these tools even in the initial planning stages.”
A 3D model is essentially a visualization of the shape of a structure, but Sugiura was equally drawn to the information embedded in BIM/CIM model objects; information beyond the visual shape of the model that could be shared and used. “For civil-engineering projects, measurements are being taken throughout the construction process,” Sugiura says. “We could take our measurement data for observed shifts, distortions, and displacements and input them on-site as attributes of the 3D models.”
At that time, Obayashi was already using Autodesk Revit and Civil 3D. To add a timeline to visualize the step-by-step construction process with color, the team used Navisworks project-review software. “For example, when pouring concrete, there was data we wanted to manage on-site, such as when, how, and where it was poured,” Sugiura says. Using Navis+ (add-on software for Navisworks developed by Itochu Techno Solutions) to manage 3D-object attributes, Obayashi could add much more attribute data to a model from an Excel spreadsheet, which made it possible to manage structural-shape information with other valuable data.
Working with CIM, Sugiura and his team were able to realize a 35 percent increase in construction-management efficiency—and pointed the company toward its future. “The youngest site foreman of the Mikusa Tunnel is now in a management role,” he says. “Employees have been able to apply their experiences with CIM toward other projects, and we are seeing measurable benefits from this approach.”
Analyzing the data shows clear points where the team was able to save time over the course of these projects. Sugiura believes that once others in the industry see how these tools can make their work easier, they will want to adopt them. “This kind of workflow streamlining is precisely what Japan’s construction industry is looking for,” he says.
While Sugiura has been an active proponent of CIM, he lets the work speak for itself. “I never tell anyone in a company they must start using CIM,” he says. “I explain the merits of using CIM and will help them adopt the systems to improve their on-site efficiency. CIM is spreading not because it is mandatory but because people are seeing successful examples of its use in the industry.”
Through industry-government-academic collaborations, CIM is spreading from Japan to China, South Korea, Singapore, and Thailand. It’s also being used on an Obayashi dam construction project in Laos.
Obayashi is applying the processes developed for the Mikusa Tunnel toward other construction projects—and moving forward with the technologies. “We will continue to share and make use of the tools at our disposal, but since new technologies are always emerging, we also have to consider how new technologies can be integrated into our existing processes,” Sugiura says. “The process may stay the same, but the tools get better and better.”
And as the country’s industry catches up to the technology, barriers such as deployment and training costs are starting to fall away. “For CIM, the tools themselves aren’t as important as how we use them,” Sugiura says. “Know-how is key. Change just for the sake of change creates problems and wastes time and money. You won’t find anyone complaining once it’s put to use.”
While adopting CIM practices was tough at the start, Japan—and other places that share an old-school approach to construction—will soon see the light at the end of the tunnel.