Integration of 3D CAD and ICT Construction: The Future of the Field Pioneered by LRTK

Background: Challenges Facing the Construction Industry and the Trend toward Digitalization

In Japan's construction and civil engineering sectors, attention to ICT construction using 3D CAD has been growing in recent years. This trend stems from industry challenges such as an increasingly severe labor shortage and the aging of skilled workers. As many veteran site technicians and surveyors retire en masse and securing younger talent becomes difficult, the limits of traditional labor-intensive construction management have become apparent. At the same time, as construction projects become more sophisticated, the hurdles for quality control and safety measures rise, increasing the need to carry out work efficiently and accurately with fewer personnel.

In response, the Ministry of Land, Infrastructure, Transport and Tourism has promoted productivity improvements on construction sites under policies such as *i-Construction*. Especially important pillars have become the use of three-dimensional models (3D CAD data) represented by BIM/CIM, as-built measurement using drones and 3D scanners, and the introduction of ICT construction equipment (machine control and guidance). Initiatives that use 3D information consistently from design through construction, inspection, and maintenance are rapidly expanding across both building and civil engineering fields. This integration of 3D CAD and ICT construction makes it possible to intuitively visualize site conditions that were hard to grasp from drawings alone and share them among all stakeholders, promising unprecedented efficiency and accuracy for projects.

Benefits and Challenges of Going 3D from Design through Construction

Centralizing the process from design to construction in three-dimensional data brings many benefits. First is the sharing and visualization of design intent. By presenting the completed image of a building or infrastructure with a 3D model, all stakeholders—including clients and subcontractors—can more easily have a common understanding. Complex structures and construction procedures can be shown three-dimensionally, making it easier to discover issues that paper drawings might miss. For example, checking clashes and interfaces between trades on the BIM model can uncover problems before construction and reduce rework.

Second is the efficiency of construction planning and management. You can automate quantity takeoffs from 3D CAD or optimize schedules and sequencing with construction simulations (4D construction planning). On site, 3D models enable automated control of heavy equipment and labor-saving surveying, and progress management can be handled digitally, greatly reducing human burden. In as-built management, parts of the process that used to rely on craftsmen's intuition and experience can now be measured and evaluated quantitatively with 3D data, suppressing quality variation.

However, challenges in transitioning to 3D have also been pointed out. First are the issues of implementation costs and human resource development. Introducing advanced 3D software and equipment requires investment, and training personnel to operate them takes time. For small and medium-sized construction firms in particular, fully utilizing cutting-edge BIM and ICT construction is a significant hurdle. Also required is a transformation of operational workflows. Switching from drawing-centered conventional workflows to 3D data-centered workflows demands internal cultural change and the establishment of data collaboration rules with other companies. Additionally, when using 3D on site, considerations such as devices and network environments, and data management issues (handling large-volume data and security) must be addressed.

Although there are benefits and challenges, the flow of construction DX (digital transformation) is irreversible. To promote the use of 3D data while lowering practical barriers, easy-to-use measurement and construction support tools that link with smartphones and tablets have emerged in recent years. A leading example of these is LRTK, introduced next.

Surveying, Layout Marking, Point Cloud Acquisition, and AR Utilization Enabled by LRTK

One of the latest technologies, LRTK, is a solution that dramatically simplifies surveying and measurement on site. LRTK is an ultra-compact GNSS receiver that attaches to a smartphone or tablet, and when combined with the phone’s built-in LiDAR sensor it can digitalize a variety of field tasks. Centimeter-level positioning that previously required specialized surveying instruments and skilled operators can be performed easily by anyone using this device. Below are concrete functions and use-case images enabled by LRTK.

• High-precision single-person surveying: Attach LRTK to a smartphone and you can continuously determine your position on the spot with centimeter accuracy. Surveying that traditionally required a total station and two-person teams can be done by one person walking to desired locations and recording point coordinates. For example, in topographic surveys, a single person can measure many points across a wide area in a short time, and there is no need to later reconcile with control points.

• Digitalization of layout marking and positioning: Design reference lines and positions can be displayed in AR on the smartphone screen and intuitively marked out on site. With LRTK's high-precision GNSS, the virtual lines and points shown through the camera virtually coincide with actual positions. This allows anyone to accurately perform tasks such as setting out building grid lines or placing structural elements, which used to rely on surveying instruments or specialized layout workers.

• High-speed 3D point cloud acquisition: By combining the smartphone’s built-in LiDAR sensor with LRTK’s positioning data, site conditions can be recorded as high-density point cloud data. A person simply walking with a smartphone can laser-scan surrounding terrain and structures, acquiring 3D data on the order of hundreds of thousands of points in a short time. Because the acquired point cloud is already tied to real-world coordinates (global positioning coordinates), it can be used directly for comparison with design data or volume calculations without the need for later alignment.

• Overlaying design models with AR: Using LRTK, it is also easy to display 3D design models (BIM/CIM models) of buildings, bridges, and other structures as AR overlays on the site view. Through a smartphone or tablet screen, planned structures or underground utilities can be overlaid at full scale in the actual space. Thanks to high-precision positioning, initial alignment adjustments are unnecessary, allowing immediate identification of differences between design and current conditions on site. This feature is powerful for pre-construction image sharing and as-built verification during construction.

In this way, LRTK covers the fundamental on-site actions of measuring, recording, and showing with a single smartphone, enabling tasks that previously required separate instruments and specialist skills to be completed by one person. For example, from setting foundation grid lines to acquiring as-built point clouds and performing AR checks against the finished model, LRTK allows site personnel to intuitively carry out these tasks on the spot. This reduces work stoppages while waiting for survey teams and enables construction to proceed with real-time situational awareness.

Examples of ICT Construction and 3D CAD Use in the Building Sector

In the building sector as well, the fusion of 3D CAD and ICT construction is bringing new value to sites. In particular, digital technology is advancing in the important building task of layout marking (setting out). Traditionally, marking out the positions of columns and walls on site required setting up surveying instruments and at least two people, making it a time-consuming task. Manual work by experienced craftsmen also carries the risk of small errors, which can lead to rework or quality degradation in subsequent stages.

AR layout marking using the aforementioned smartphone AR technology is now beginning to appear. For example, in reinforced concrete structures, one method is to mark column positions on the floor while viewing the column base positions on the BIM model displayed on a tablet. High-precision AR positioning makes it possible to accurately set out positions without manual tape measures or snap lines, dramatically reducing the time required for layout marking. On one construction site, introducing AR layout marking reduced a task that previously took two people a full day to complete to one person finishing within a few hours, achieving zero rework in that case.

Other new attempts to align BIM models with the field are increasing in building projects. For example, in interior work, AR on a tablet can be used to check whether piping and ducts above ceilings are installed as designed. By displaying the completed model in a way that allows on-the-spot ‘see-through’ inspection during construction, invisible errors can be prevented and clash checks can be done at the site level. Moreover, scanning in-progress structures and equipment with a smartphone to create 3D data and comparing it to the BIM design model enables immediate detection of as-built deviations, demonstrating an emerging advancement in quality control.

Examples of ICT Construction and 3D CAD Use in the Civil Engineering Sector

In civil engineering, where large sites and terrain are the norm, the benefits of 3D data and ICT construction are even more pronounced. Below are examples practiced in roadworks, land development, bridge construction, and other projects.

First is earthworks (land development and excavation). On large development sites, as-built measurement traditionally required taking many survey points and could take days to calculate earthwork volumes. In contrast, a technician performing a mobile scan with an LRTK-equipped smartphone can, for example, acquire hundreds of thousands of point cloud points over a 50 m square site in 5–10 minutes. If point-cloud differences with the previous measurement are computed in the cloud immediately after acquisition, fill and excavation volumes can be determined instantly. In sites using this approach, daily as-built management time has been dramatically reduced, and it has been evaluated as if “one person’s work became equivalent to two people.” This is a good example of visualizing progress in real time with limited personnel.

Next is utilizing design data in roadworks. In a road widening project, existing terrain was 3D scanned with LRTK before construction, and the design 3D model was overlaid on that point cloud for planning review. Visualizing the planned fills and structures on-site with AR revealed inconsistencies between the design plan and actual terrain that had been overlooked at the drawing stage, prompting a revision of construction methods in advance. During construction, the current surface was measured with LRTK at each excavation stage, and point cloud data were shared immediately to prevent “over-excavation” or “under-excavation.” As a result, high-quality work with little variation in as-built outcomes was achieved. Processes that used to require calling in a specialized surveying team for later verification could be completed by site staff on the spot, directly preventing rework and shortening construction schedules. In addition, sharing the completed image via tablet AR with heavy equipment operators and clients helped align everyone's vision and reduced communication loss.

Furthermore, infrastructure maintenance and safety measures also see applications of 3D×ICT. For example, in water and sewer works, municipalities are using LRTK to collect accurate position data for buried pipes and manholes and are digital-mapping them at centimeter-level accuracy. This allows workers to identify the locations of underground utilities on site—locations that were previously known only from drawings—and greatly reduces the risk of damaging existing pipes. Visualizing underground pipeline routes on a smartphone AR screen during excavation helps prevent near-miss incidents and improves safety. In disaster response, LRTK has proven powerful even in areas where communication infrastructure is down. By utilizing the augmentation signal (CLAS) available from the Michibiki satellites, municipal staff were able to perform high-precision measurements at disaster sites alone, recording landslide extents and damage conditions in 3D and sharing them immediately—allowing much faster initiation of restoration planning than before. Tools that enable high-precision single-person measurements make it possible to quickly and safely grasp conditions even in emergencies.

Efficiency, Safety, and Quality Improvements Brought to Sites

From the examples above, the effects that the fusion of 3D CAD and ICT construction brings to sites can be summarized as follows:

• Dramatic improvement in work efficiency: Digitalizing processes such as surveying, layout marking, and as-built verification makes it possible to significantly shorten times compared to conventional methods. One person can perform work that used to take multiple people, maintaining and improving productivity despite labor shortages. Real-time data sharing and analysis reduce waiting times and duplicate work, directly contributing to shorter project schedules.

• Improved safety: The reduction of surveys in hazardous locations or near heavy equipment and the ability to confirm things remotely or via AR lower worker risk. More accurate knowledge of buried utilities reduces the chance of accidentally damaging structures, contributing to safer construction. Because accurate work becomes possible without relying on experts, human errors due to lack of skill also decrease.

• Assurance of quality and precision: Progressing construction while continually comparing the site with the design model minimizes positional offsets and as-built variation. Digital dimensional control enables millimeter-level precision pursuit, suppressing rework and construction defects. Inspection records can also be accumulated as 3D data, becoming valuable, high-quality information assets for future maintenance and verification.

• Smoother communication: Sharing visual, intuitive information in the form of 3D models reduces recognition gaps among clients, designers, and contractors. Confirming the finished image together around a tablet on site makes meetings smoother. This reduces the effort required for explanations and consensus-building, allowing all stakeholders to work toward the same goal image during construction.

Thus, consistent use of 3D data not only improves operational efficiency but also innovates site safety culture and quality management methods, deepening collaboration among stakeholders. In accelerating construction site DX, the fusion of 3D CAD and ICT construction has become an indispensable piece.

Future Outlook: The Digital Future and the Benefits of Introducing LRTK

Construction and civil engineering sites are now digitalizing at an unprecedented pace. One envisioned future is the realization of a digital twin in which the site and the office, and the physical asset and the digital model, are synchronized in real time. If sensors and IoT are linked with 3D models to enable continuous monitoring of construction progress and quality, productivity and safety will further improve. New technological innovations based on 3D data, such as AI-powered automatic detection and coordination with robotic construction, are also expected.

As a first step toward such a future, it is important to introduce easy-to-use digital tools on site. Smartphone surveying devices like LRTK lower the barriers to digitalization thanks to their simplicity. Even without specialists to operate dedicated equipment, site staff can begin surveying, verification, and AR utilization, allowing small sites and teams with limited personnel to feel the effects quickly. The initial investment and training costs are relatively modest, and the ability to leverage existing smartphones is a clear implementation advantage.

Moreover, LRTK’s all-in-one capabilities make it an optimal entry point for site DX. It can first be introduced as a high-precision simple surveying tool and then gradually expanded to point-cloud scanning and AR-based construction management. Cloud integration enables seamless information sharing with the office, supporting new working styles such as managing multiple remote sites. Above all, enabling everyone on site to handle 3D data contributes to building resilient organizations that do not rely on individual specialists.

The future of the field that LRTK is pioneering is a new construction style where seasoned expertise and digital technology are harmonized. Bringing design information created in 3D fully to the site and feeding site-acquired data back into design and management will establish a cycle that dramatically improves productivity and quality in construction projects. As labor shortages become increasingly severe, the momentum to “solve problems with technology rather than relying on people” will accelerate. As a means to achieve this, adopting easy-to-use surveying and construction support tools like LRTK as early as possible is a significant advantage. For all technicians ready to take a step toward site DX, such integration with the latest technologies holds the key to a brighter future.