Introduction to CIM: Basic Terms, Mechanisms, and How to Use It You Might Be Hesitant to Ask About｜LRTK

In recent years, you'll increasingly hear the term CIM in the construction industry. The Ministry of Land, Infrastructure, Transport and Tourism (MLIT) is also promoting its introduction as part of i-Construction, and it has become an important industry keyword. However, some people may think, "I've heard of it, but I honestly don't really understand it," or "It's awkward to ask about now..." This article explains the basic terms, mechanisms, and concrete ways to use CIM in a clear and easy-to-understand manner for beginners.

What is CIM? Differences from BIM and the Background

CIM (Construction Information Modeling/Management) is a method in the construction and civil engineering fields that utilizes three-dimensional models (3D models) to centrally manage various related information. Simply put, it is an initiative to consolidate drawings, construction information, and so on into digital 3D models and use them.

Originally, the architectural field had already adopted a 3D utilization method called BIM (Building Information Modeling/Management). CIM applies the BIM concept from the architectural field to the civil engineering field and is a concept proposed by the MLIT in 2012 to improve the efficiency of construction operations. After trials and phased implementation, from fiscal 2023 the MLIT began the principle application of BIM/CIM to MLIT-direct civil engineering projects, and CIM use is becoming standard even in public works.

So what is the difference between BIM and CIM? The basic idea is common, but they target different fields.

• BIM: Targets buildings such as offices and houses (3D information models for the architectural field)

• CIM: Targets civil engineering structures such as roads, bridges, dams, and tunnels (3D information models for the infrastructure field)

In short, both mean "utilizing three-dimensional models," but it is useful to think of BIM for architecture and CIM for civil engineering. Overseas, the term "BIM" is often used to cover construction in general, and in Japan the two are sometimes referred to together as "BIM/CIM."

CIM Mechanism and Features: Visualization and Efficiency with 3D Models + Attribute Information

The keywords of CIM are "three-dimensional models" and "attribute information." According to the MLIT's BIM/CIM portal site, the 3D model handled in CIM refers to "information that expresses the shape of the object in three dimensions," and attribute information refers to "various types of information attached to the 3D model, such as components and construction history"【※】. The combination of these three-dimensional models and attribute information is the CIM model.

Traditionally, the construction industry has advanced design and construction using planar 2D drawings. While 2D drawings are easy to create, they require experience to visualize the finished form in three dimensions, making reading errors and mismatches in understanding among stakeholders likely. Paper drawings also make information sharing cumbersome, which is one of the reasons productivity has been slow to improve.

By introducing CIM, information can be intuitively shared and reviewed on 3D models. By linking detailed information of components and structures to a digital 3D space, all stakeholders can more easily share the same three-dimensional image, helping prevent design errors and improve construction quality. For example, because equipment and structural interference (collisions) can be checked in advance on a 3D model, retrofits such as "components not fitting on site" can be reduced. Also, because visualizing construction contents that was difficult with paper drawings becomes easy, there is the advantage of being able to explain plans to non-experts more readily.

CIM is not merely 3D modeling but is characterized by being a "mechanism to utilize information." By using the attribute data linked to the 3D model, you can automate quantity calculations and cost estimates, digitally record and share progress and history, and achieve various operational efficiencies. Through CIM introduction, it is possible to review the entire construction project workflow and pursue efficiency improvements through approaches different from traditional ones.

Two noteworthy concepts are "front-loading" and "concurrent engineering." Front-loading is a method of concentrating effort early in the project (upstream processes) to eliminate problems, and using CIM to perform detailed simulations and verifications during the design phase minimizes rework in later stages. For example, if temporary works plans and construction procedures are reviewed in 3D and the optimal plan considering safety and efficiency is decided beforehand, construction-stage troubles decrease and overall efficiency improves.

Concurrent engineering, on the other hand, refers to a method where different processes such as design and construction proceed in parallel. Since CIM allows stakeholders to share design data in real time, it becomes easy to incorporate input from construction personnel during design or to immediately reflect design changes in construction plans, facilitating cross-departmental simultaneous progress. As a result, decision-making speeds up, shortening construction time and improving quality.

Thus, CIM is a system that achieves both visualization and efficiency through "3D models + information utilization." Next, let's look at concrete ways it is used on site.

※Reference: MLIT BIM/CIM portal site "First-Time BIM/CIM"

CIM Use Cases: How Is It Used in Design, Construction, and Maintenance?

CIM can be used at all stages of a construction project. Let's look at the main uses and scenarios by stage.

• Design stage: 3D models help accelerate consensus-building among stakeholders. It is easier to share the completed image that is hard to convey with plan drawings alone, making alignment among designers, clients, and owners smoother. Additionally, automatic earthwork volume calculation from 3D terrain-inclusive design data and quantity estimation of materials from models make accurate quantity and cost estimates possible. Using 3D models also allows for visual explanations to local residents, making it easier to gain understanding and cooperation.

• Construction stage: CIM is powerful on construction sites as well. For example, construction procedures and progress can be visualized in 3D, enabling everyone on site to work with a common understanding. If design changes occur, updating the model data allows instant sharing of the latest information by all, preventing communication gaps. Importing CIM models into ICT construction machinery (machine guidance / machine control) enables high-precision construction through automated control, improving both work efficiency and accuracy. Also, comparing point cloud data (3D measurement data) obtained by drones or terrestrial laser scanners with the design model to check as-built conditions can streamline quality control and inspection. Furthermore, CIM is useful for safety management by identifying hazardous areas in advance on 3D and taking countermeasures.

• Maintenance stage: CIM is also helpful for post-completion maintenance. If inspection results and repair histories are accumulated as attribute information in the CIM model for each structure, past records can be centrally managed. For example, attaching inspection records to the model allows intuitive understanding of aging degradation and aids in planning future inspections and repairs. Because necessary information can be searched from the model without pulling out ledgers or drawings, a major benefit is that you can quickly retrieve accurate information in emergencies such as disasters. With centralized data, information sharing among multiple departments and related agencies becomes smoother, contributing to efficient maintenance of social infrastructure.

As described above, CIM delivers various effects that directly lead to improved productivity and quality in each phase of design, construction, and maintenance. So where should you start when actually introducing CIM? Finally, let's look at the key points.

Steps to Introduce CIM: Points for First-Time Implementation

CIM is highly beneficial, but for companies introducing it for the first time it is difficult to replace everything at once. The MLIT also recommends phased implementation in its guidelines. Below are the general steps for CIM introduction.

• Current situation analysis and goal setting: Identify your company's operational issues and clarify the problems you want to solve or the goals you want to achieve with CIM introduction. Setting concrete goals such as "reduce design errors" or "eliminate rework in construction" is important.

• Human resource development: Develop personnel who can handle 3D CAD and BIM/CIM software. Secure personnel with 3D modeling and data utilization skills through in-house training or external seminars.

• Environment preparation: Prepare the hardware and software necessary for CIM. Introduce tools appropriate to your purpose, such as high-performance PCs and tablets, 3D modeling software, and devices for acquiring point cloud data. Also set up an internal data-sharing infrastructure (cloud storage, etc.).

• Trial on small projects: Rather than starting with a large-scale project, first introduce CIM experimentally on a small project. By actually creating 3D models and using them in each process, you will see the effects and issues.

• Effect verification and improvement: Verify the results of the trial introduction, and organize what worked well and what became an issue. Collect feedback from stakeholders and improve the operational flow and tool selection.

• Full-scale introduction: Once preparations are complete, introduce CIM across the company and on a full scale. Incorporate it into standard business flows and internal regulations to ensure adoption. Prepare guidelines as necessary and continuously carry out human resource development and technical verification.

By taking a phased approach, even companies new to CIM can transition without strain. The key to success is to gain experience within the company while gradually expanding the scope of application.

Conclusion: Accelerate Construction DX with CIM

CIM (Construction Information Modeling/Management) is an important technology driving digital transformation in the construction industry. By combining three-dimensional models with related information, productivity and quality improvements can be expected in design, construction, and maintenance. Incorporating concepts like front-loading and concurrent engineering enables efficiency across the entire project and contributes to work-style reform, making the impact of CIM substantial.

The MLIT is promoting CIM adoption, and it will increasingly become an industry standard. To avoid falling behind industry trends, responding to CIM is an unavoidable issue for future construction companies. Companies that have not yet introduced it should definitely consider starting gradually with what they can do.

One major hurdle when starting CIM is the digitization of site data. To utilize CIM, you first need accurate three-dimensional data of the site (terrain and structure shapes, coordinates, etc.). Traditionally, this required expensive surveying equipment and specialized technicians, making it a high hurdle. This is where new surveying methods using smartphones are noteworthy.

For example, LRTK is a next-generation tool that enables anyone to easily achieve centimeter-level positioning (half-inch accuracy) by attaching a small high-precision GNSS receiver to a smartphone. Even people who have never handled professional surveying equipment can operate it intuitively and conduct site surveying and as-built measurements easily by themselves. Because you can acquire terrain elevation differences and structure coordinates in a short time and upload them to the cloud, it is easy to immediately share data within the company and reflect it in CIM models. Tasks that were previously troublesome, such as acquiring point cloud data and as-built management, can be completed with just a smartphone when using LRTK. It is also possible to overlay 3D model data created during design onto the actual site using AR (augmented reality) functions on the smartphone, enabling digital-to-field applications such as marking pile-driving positions.

By adopting simple surveying with LRTK, you can obtain the digital on-site information needed for CIM inexpensively and efficiently. It is an ideal approach for those who want to "first try 3D-ifying the site." It is a reliable tool that significantly lowers the hurdles to CIM introduction.

The future of construction sites is unquestionably digital. Using CIM to streamline operations will directly enhance future competitiveness. Please consider challenging CIM within your own company. And while actively incorporating the latest technologies such as LRTK, why not take the first step toward on-site DX?

[※ MLIT BIM/CIM Portal Site](https://www.nilim.go.jp/lab/qbg/bimcim/bimcimindex.html)｜[LRTK Official Site](https://www.lrtk.lefixea.com)