Understand What CIM Is in 3 Minutes: A Simple Explanation from the Basics

Have you heard the term "CIM," which has been mentioned frequently in the construction industry recently? You may have heard of the term BIM, but CIM might be new to you. CIM refers to the use of three-dimensional models and information management in the construction field. In this article, we will gently explain the basics of CIM in a way that's easy for beginners to understand. It takes about three minutes to read, so please stay with us until the end.

What is CIM? (Basic Explanation)

CIM (pronounced "shim") is an abbreviation of "Construction Information Modeling/Management," and in Japanese it is called "コンストラクション・インフォメーション・モデリング／マネジメント". Originally, in the building sector, a method of utilizing three-dimensional models called BIM (Building Information Modeling) had become widespread, and CIM is the application of this concept to the civil infrastructure field. Simply put, it refers to an initiative to centrally manage and share the drawings and construction information used in construction projects as three-dimensional data.

In CIM, three-dimensional models are created on a computer to reproduce civil engineering structures such as roads, bridges, and dams, and various additional information (attribute information) such as the names, dimensions, quantities, and construction periods of the components and materials used in the works are linked to those models. These three-dimensional models are used at every stage of a project, from planning and design through construction to post-completion maintenance management. By having stakeholders refer to a common model, everyone can obtain the necessary information, enabling efficient management of the entire project—this is the aim of CIM.

![CIM overview diagram]() Figure: Conceptual diagram of CIM. Various attribute information is linked to the 3D model and centrally utilized across the entire project.

Note that overseas it is common to refer to both architecture and civil engineering collectively as "BIM", but in Japan the terms BIM and CIM are sometimes used differently depending on the field. However, in recent years the notation "BIM/CIM" to cover both architecture and civil engineering has also become established. Both share the common point of "adding information to a 3D model and making use of it," and the general concept is the same.

Background Behind the Growing Interest in CIM

So why is CIM receiving so much attention now? Behind this is the construction industry's long-standing challenge of low productivity and the broader societal trend toward digitalization (DX). At construction sites in Japan, paper drawings and manpower-intensive management have long been the norm, and productivity has been pointed out as low compared with other industries. The aging of skilled technicians and the shortage of young talent are also serious. To overcome these circumstances, the Ministry of Land, Infrastructure, Transport and Tourism launched in 2016 a project called i-Construction (ai-Construction) to promote a productivity revolution at construction sites through the use of ICT technologies. For example, the Ministry has set a goal of improving construction site productivity by 20% (two-tenths) by fiscal 2025, and the widespread adoption of BIM/CIM is regarded as an important key to achieving that. One of the pillars put forward is the introduction of three-dimensional models into the construction process, that is, the expanded use of BIM/CIM.

The Ministry of Land, Infrastructure, Transport and Tourism gradually expanded the scope of CIM after trials and finally, from the 2023 fiscal year (Reiwa 5), began principle-based application of BIM/CIM (effectively making it mandatory) for all directly managed construction works and services except for small-scale projects. This "principle-based application" is a policy that makes the introduction of CIM the default for national directly managed projects unless there are exceptional circumstances. In other words, the use of CIM will become the assumed norm for future public works. For construction companies and local governments, responding to CIM is an unavoidable challenge and represents a major turning point for the entire industry. The Ministry has also launched the ["BIM/CIM Portal Site"](https://www.nilim.go.jp/lab/qbg/bimcim/bimcimindex.html), which compiles standards and case studies related to BIM/CIM and publishes the latest information useful for putting CIM into practice.

Benefits of CIM

What benefits can be gained by implementing CIM? Here are some of the main advantages.

• Intuitive and easy to understand: Compared with flat 2D drawings, a 3D model lets you visualize the finished form in three dimensions. It is easier for non-specialists to understand and helps when explaining plans to clients and local residents. Because designers and contractors can review the same model together, misunderstandings are reduced and communication becomes smoother.

• Reduce rework and improve efficiency: Because detailed structural review and clash detection (such as piping or rebar collisions) can be performed from the design stage, there are fewer drawing changes and do-overs once construction begins. Even on projects involving multiple trades and subcontractors, the model enables constant sharing of up-to-date information, reducing transmission errors and allowing the overall schedule to proceed more efficiently.

• Reduce waste to cut costs: By conducting thorough simulations and reviews before construction, you can reduce material waste and rework caused by construction errors, which leads to lower unnecessary costs. For example, detecting clashes between systems in advance can prevent additional on-site work and wasted labor.

• Smooth information sharing: Because drawings, specifications, schedules, and other project information are integrated into the 3D model, stakeholders can easily share the information they need. Compared with paper drawings or managing separate files, the effort required to find and transmit data is greatly reduced. Meetings and reports are reduced as well, increasing transparency across the entire project.

• Prevent mistakes and improve quality: Because construction flow simulations and clash checks can be performed in advance on the 3D model, human error and construction mistakes on site can be greatly reduced. Even for complex structures, preventing inconsistencies beforehand reduces the risk of schedule delays and contributes to higher finished quality.

Use cases for CIM

CIM is useful in various aspects of a project. Let’s look at examples of how it is utilized at each stage.

• Design stage: *Planning and consensus building using 3D models*. During planning and design, stakeholders use 3D models created with CIM to share and review the envisioned final outcome. Shapes that are difficult to understand on plan drawings and how they harmonize with the surrounding environment can be intuitively grasped with 3D models. They are also used as explanatory materials for clients and local residents, facilitating smoother consensus building. In addition, by conducting detailed design reviews on the model and checking for clashes between structures in advance, rework in later stages can be prevented.

• Construction stage: *Optimization of construction planning and progress management*. CIM is also effective when reviewing construction sequencing. For example, construction procedures can be visualized with 4D simulation (3D + time axis) to develop safe and efficient construction plans. On site, stakeholders use 3D models to establish a common understanding of how construction should proceed and to verify the as-built condition (the shape of the completed structure). Furthermore, if construction progress is managed on the model, delays or construction errors can be detected early, enabling rapid response.

• Maintenance stage: *Utilization for digital maintenance and inspection*. CIM models are also valuable for maintaining completed structures. If inspection records and repair histories related to the completed structure are linked to and stored in the model, even when personnel change, past information can be intuitively understood in 3D. Tasks that previously involved flipping through paper drawings and ledgers can now search and reference necessary data on the digital model, leading to more efficient maintenance operations and prevention of overreliance on specific individuals.

Against this backdrop, the adoption of CIM is now spreading not only among major general contractors (large integrated construction firms) but also to medium-sized and small construction companies and local government projects. The government is also promoting its dissemination by providing training content and publishing case studies, and the use of digital technologies across the construction industry is accelerating; the 3D models built with CIM are expected to become the foundation of digital twins (technology that reproduces and monitors real-world structures in virtual space).

Challenges and Key Points of CIM Implementation

CIM has many benefits, but several challenges have been pointed out when implementing it. First, as a personnel-related challenge, there is a shortage of people proficient in new 3D technologies. Transitioning from traditional work centered on 2D drawings to the use of 3D models requires in-house training and the accumulation of know-how. However, in recent years the Ministry of Land, Infrastructure, Transport and Tourism has published [training content for CIM education](https://www.nilim.go.jp/lab/qbg/bimcim/about.html), and efforts to support human resource development are progressing, with an increasing number of engineers—particularly younger ones—acquiring 3D skills.

Next, there are also cost and equipment-related challenges. The initial investment to acquire high-performance 3D design software and surveying equipment can be a bottleneck. However, this hurdle is gradually lowering thanks to the emergence of inexpensive software and the partial use of external services. For example, in recent years, high-precision GNSS surveying equipment that traditionally cost several million yen has become replaceable by inexpensive compact devices, reducing the cost burden of on-site measurements. Also, by taking a phased approach to CIM starting from the necessary scope, organizations can avoid large-scale investments and proceed with implementation while verifying the benefits.

Furthermore, as challenges related to data and operations, it is also important to establish rules for information sharing both inside and outside the organization. Even if 3D models are introduced, they cannot be used efficiently if data formats vary between departments and companies. In this respect, the Ministry of Land, Infrastructure, Transport and Tourism is recommending and making mandatory international standards such as LandXML and IFC as standard formats in BIM/CIM contract documents, and an environment that allows smooth data exchange between different software is being put in place. Companies should also formulate operational guidelines and clarify model update procedures and file management rules to prevent reliance on specific individuals and enable unified CIM use across the entire project.

Although challenges remain, national and industry-wide measures are progressing, and the barriers to CIM adoption are gradually lowering. In particular, for on-site 3D measurement, simple surveying methods that leverage drones, laser scanners, and smartphones have emerged, making it significantly easier to undertake than before. In the next chapter, we will introduce a simple surveying method using a cutting-edge tool called LRTK as one example.

Simplified Surveying Using LRTK

To maximize the effectiveness of CIM, it is essential to accurately digitize the original on-site survey data. No matter how much you utilize 3D models, creating those models requires surveying and scanning the site’s topography and structures to capture and import that information. Traditionally, such surveying and point cloud measurement required expensive specialized equipment and multiple-person teams, but in recent years technological advances have made it possible for anyone to easily perform high-precision 3D surveying.

A representative example is the solution LRTK (Eru Aru Tii Kee) provided by Refixia Co., Ltd. LRTK consists of a compact, high-precision GNSS receiver that attaches to a smartphone or tablet and a dedicated app, enabling centimeter-class positioning with a palm-sized device (cm level accuracy, half-inch accuracy). Using this, surveying work that used to be performed by two people can be completed by a single person, leading to labor savings and faster on-site operations. Furthermore, because it leverages existing smartphones, it is attractive for its ability to significantly reduce initial deployment costs. Measured data can be saved and shared to the cloud in real time, and can be easily imported into and used in CIM 3D models.

![LRTK Phone Device]() Figure: A smartphone with an LRTK receiver attached. With this compact device, a single person can perform surveying with centimeter-level accuracy (cm level accuracy (half-inch accuracy)).

The three main features of the LRTK system are as follows.

• Centimeter-level high-precision positioning: RTK (real-time kinematic) enables positioning on smartphones with errors kept to less than a few cm (in). It can adequately handle situations that require millimeter-level (mm (in)) precision control, such as setting out bridge positions or longitudinal road surveys.

• Low cost and minimal equipment: Because you can start simply by attaching a small receiver to a smartphone, there is no need to assemble conventional expensive surveying equipment. You can significantly reduce the purchase cost of dedicated equipment, making it affordable for small and medium-sized enterprises and on a per-site basis. The device is also lightweight and compact enough to fit in the palm of your hand, and has a built-in battery so it can be easily carried to the field.

• Simple and usable by anyone: Surveys can be performed with intuitive operation using a dedicated app, designed to be easy to handle even by people who have not received special training. Because one person can complete surveying tasks, it reduces workload even at sites facing labor shortages. For example, in road and railway construction where trains or vehicles pass, shortening working time leads to improved safety. Also, acquired data can be shared immediately via the cloud, so there is no need to organize data after returning to the office.

For example, when you take a photo with a smartphone camera, the coordinates of the captured objects are automatically recorded. Also, if you scan the surroundings with the smartphone’s built-in sensors, you can obtain point cloud data (3D measurement data composed of countless points) in a short time. You can easily compare the as‑built/current-condition data obtained this way with a CIM model and check discrepancies between the design drawings and the actual work on site. Furthermore, LRTK also supports AR (augmented reality) functionality, allowing 3D design models to be overlaid on live images on a smartphone screen. For example, you can intuitively project a planned building model onto the actual site to confirm its placement, or overlay constructed structures with design data to verify construction accuracy.

In this way, by leveraging simplified surveying with LRTK, field measurements that previously relied on specialist technicians become significantly more accessible and efficient. By enabling bidirectional use of highly accurate on-site data and the CIM model, the benefits of CIM can be further realized. Even beginners who are considering introducing CIM should be able to take the first step toward 3D utilization easily by using modern tools like LRTK.