The Fusion of 3D CAD and ICT Construction: The Future of Sites Pioneered by LRTK

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

In Japan’s construction and civil engineering industry, attention to ICT construction using 3D CAD has been growing in recent years. Behind this trend are industry challenges such as a worsening labor shortage and an aging workforce. While many veteran site technicians and surveyors are retiring in large numbers, it is becoming difficult to secure young talent, and the limits of traditional manpower-intensive construction management are becoming apparent. At the same time, as constructed works become more sophisticated, the hurdles for quality control and safety measures have risen, increasing the need to perform tasks efficiently and accurately with fewer personnel.

In response to these circumstances, the Ministry of Land, Infrastructure, Transport and Tourism has been promoting productivity improvements on construction sites under policies such as *i-Construction*. In particular, the utilization of three-dimensional models (3D CAD data) represented by BIM/CIM, as well as as-built measurements by drone and 3D scanner, and the introduction of ICT construction machinery (machine control/guidance) are important pillars of ICT construction that leverages digital technologies. Initiatives that make continuous use of 3D information from the design stage through construction, inspection, and maintenance are rapidly spreading in both the building and civil engineering fields. This fusion of 3D CAD and ICT construction is expected to make site conditions that were difficult to grasp on drawings intuitively visible and shareable among all stakeholders, enabling projects to proceed with unprecedented efficiency and accuracy.

Benefits and Challenges of Going 3D from Design through Construction

There are many benefits to unifying the process from design to construction with three-dimensional data. First is the sharing and visualization of design intent. By showing 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 are shown three-dimensionally, making it easier to discover issues in advance that would be hard to notice on paper drawings alone. For example, by checking coordination and clashes among specialty construction trades on a BIM model, problems can be identified before construction and rework reduced.

Second is efficiency in construction planning and management. Quantities can be automatically extracted from 3D CAD, and construction simulations (4D construction planning) can optimize schedules and sequences. On site, 3D models enable automated control of heavy equipment and labor-saving surveying, and digital progress management can greatly reduce human workload. In as-built management, aspects that previously relied on craftsmen’s intuition and experience can now be quantitatively measured and evaluated with 3D data, suppressing variability in quality.

On the other hand, challenges in going three-dimensional have also been pointed out. First is the issue of introduction cost and human resource development. Introducing advanced 3D software and equipment requires investment, and it takes time to train personnel capable of operating them. Especially for small and medium construction companies, the hurdle to fully utilize cutting-edge BIM and ICT construction is by no means low. Also, transforming operational workflows is necessary. Switching from drawing-centered traditional work to a 3D data-centered workflow requires internal awareness reform and establishment of data exchange rules with other companies. Furthermore, when using 3D on site, challenges related to devices, network environments, and data management (handling large-volume data and security, etc.) must be considered.

Although there are benefits and challenges, the flow of construction DX (digital transformation) is irreversible. To lower practical hurdles while promoting the use of 3D data, simple measurement and construction support tools that link with smartphones and tablets have appeared in recent years. A representative of these tools is LRTK, introduced next.

Surveying, Layouting, Point Cloud Acquisition, and AR Utilization Realized by LRTK

One of the latest technologies, LRTK (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 smartphone’s built-in LiDAR sensor it can digitize a wide range of site tasks. Centimeter-level accuracy (half-inch accuracy) positioning that previously required special surveying instruments and skilled technicians can be performed easily by anyone using this device. Below are specific functions enabled by LRTK and examples of how they can be used.

• High-precision single-person surveying: If you attach LRTK to a smartphone, you can continuously determine your position on the spot to centimeter-level (half-inch-level) accuracy. Surveying that traditionally required a total station and a two-person team can be done by one person who walks around and records 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 later need to reconcile against control points.

• Digitalization of layouting and staking-out: Design reference lines and positions can be displayed on the smartphone screen in AR and intuitively marked on site. Thanks to LRTK’s high-precision GNSS, the virtual lines and points shown through the camera virtually coincide with their actual positions. This enables anyone to accurately perform layout tasks such as setting building axes or placing structures, tasks that used to depend on survey instruments or specialized layout workers.

• Rapid acquisition of 3D point clouds: By combining the smartphone’s built-in LiDAR sensor with LRTK position information, site conditions can be recorded as high-density point cloud data. A responsible person can simply walk around holding a smartphone to laser-scan the surrounding terrain and structures and acquire 3D data on the order of hundreds of thousands of points in a short time. Because the acquired point cloud is tied to real-world coordinates (global positioning coordinates) from the outset, it can be used directly for comparisons 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 in the site scenery. Through a smartphone or tablet screen, you can superimpose full-scale models of planned structures or underground utilities onto the real space in front of you. High-precision positioning removes the need for initial alignment adjustments, allowing immediate recognition of differences between the design and as-built conditions on site. This function is powerful for sharing pre-construction images and for as-built checks during construction.

In this way, LRTK covers the basic on-site actions of measuring, recording, and showing with a single smartphone, enabling tasks that used to require separate equipment and specialist technicians to be completed by one person. For example, from setting foundation axes to as-built point cloud measurement and even AR checks of the finished model, site personnel can intuitively perform these tasks on the spot with LRTK. This reduces work stoppages while waiting for surveying, and makes it possible to proceed with construction while grasping the situation in real time.

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

In the building sector as well, the fusion of 3D CAD and ICT construction is bringing new value to sites. Digital technologies are advancing particularly in the important building task of layouting (staking out). Traditionally, staking out the positions of building columns and walls on site required setting up surveying instruments and at least two people, a time-consuming process. Manual work by experienced craftsmen carried the risk of small errors, and positional deviations could lead to rework or deterioration of quality in later stages.

Currently, AR layouting using smartphone AR technology is emerging. For example, in a reinforced concrete building, when marking column positions, workers can view the column base positions on a BIM model displayed on a tablet and mark the floor accordingly. High-precision AR positioning makes it possible to accurately stake out positions without manual tape measurements or string lines, drastically shortening the time required for layouting. On one construction site, the introduction of AR layouting enabled column position staking—which used to take two people a full day—to be completed by one person in a few hours, achieving zero rework.

There are other new initiatives in the building field that compare BIM models with site conditions. For example, during interior work, AR on a tablet can be used to confirm whether pipes and ducts above the ceiling are installed as designed. By displaying the finished model as if you could see through structures while working, it becomes possible to check for installation errors or clashes of hidden elements at the site level. Moreover, by scanning in-progress structures and equipment with a smartphone and converting them to 3D data to compare with the BIM design model, it is becoming possible to instantly detect as-built deviations and thus advance quality control.

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

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

First, the use in earthworks (land development and excavation). Traditionally, on large-scale development sites it could take several days to take numerous survey points and calculate earthwork volumes for as-built measurement. In contrast, if a responsible engineer performs a mobile scan while walking the site with an LRTK-equipped smartphone, even a 50 m (164.0 ft) square site can yield hundreds of thousands of point cloud points in about 5–10 minutes. If point cloud differences against the previous survey are computed on the cloud immediately after acquisition, embankment and excavation volumes can be understood instantly. On sites using this method, the time required for daily as-built management has been dramatically reduced, and it has been evaluated as if “one person’s work doubled the workforce.” This is a good example of visualizing progress in real time even with limited personnel.

Next is utilization of design data in roadworks. In one road widening project, the existing terrain was scanned in 3D with LRTK before construction, and the design 3D model was overlaid on the point cloud for plan review. When the planned embankments and structures were visualized on site using AR, inconsistencies between the design plan and the actual terrain that were not apparent on drawings were discovered, and construction methods were revised in advance. During construction, the current shape was measured with LRTK after each excavation and point cloud data was shared immediately to manage against “over-excavation” or “under-excavation.” As a result, high-quality construction with consistent as-built results was achieved. Processes that used to call a specialized surveying team for later verification could be completed by on-site staff, directly preventing rework and shortening the schedule. Additionally, sharing the finished image on a tablet AR screen with heavy equipment operators and clients aligned everyone’s image and reduced communication loss.

Furthermore, in infrastructure maintenance and safety measures, 3D×ICT utilization is also being seen. For example, in water and sewer systems, local governments are using LRTK to collect accurate positional data of buried pipes and manholes across cities and are digitizing them into maps with centimeter-level accuracy (half-inch accuracy). This enables construction personnel to accurately identify the locations of underground utilities on site rather than relying solely on drawings, greatly reducing the risk of accidentally damaging existing pipes. Excavation performed while visualizing underground piping routes on a smartphone AR screen helps prevent near-miss incidents and improves safety. In disaster response, LRTK proved powerful even in areas where communications infrastructure was disrupted. By utilizing the supplemental signal (CLAS) from the Quasi-Zenith Satellite System that can be received outside mobile networks, municipal staff could measure disaster-affected sites alone, immediately recording and sharing 3D data of landslide extents and damage. As a result, recovery planning could begin much faster than before. A tool that enables high-precision single-person measurement allows rapid and safe situational assessment in emergencies.

Efficiency, Safety, and Quality Improvements Brought to Sites

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

• Dramatic improvement in work efficiency: By digitalizing processes such as surveying, layouting, and as-built inspection, significant time savings can be achieved compared to conventional methods. One person can perform the work of multiple people, maintaining and improving productivity even amid labor shortages. Real-time data sharing and analysis reduce waiting times and duplicated tasks, directly shortening construction schedules.

• Improved safety: Surveying work in dangerous high places or around heavy equipment is reduced, and remote measurement and AR-based checks lower the risk to workers. More accurate identification of the locations of underground utilities helps prevent accidental damage to structures, leading to safer construction. Additionally, because accurate work can be performed without relying on specialists, human errors due to skill shortages are reduced.

• Assurance of quality and accuracy: Because construction can proceed while constantly comparing design models to site conditions, positional deviations and variability in as-built results are minimized. Digital dimension management enables pursuit of precision to the millimeter level, reducing rework and construction defects. Inspection records can also be stored as 3D data, becoming high-quality information assets useful for future maintenance and verification.

• Smoother communication: Sharing visual and intuitive information in the form of 3D models reduces recognition gaps among clients, designers, and constructors. Reviewing the completed image together around a tablet on site makes meetings proceed smoothly. This reduces the effort required for explanations and consensus building, allowing all stakeholders to advance construction with the same goal image.

In this way, consistent use of 3D data is not limited to mere operational efficiency; it also innovates site safety culture and quality management methods, deepening collaboration among stakeholders. The fusion of 3D CAD and ICT construction has become an indispensable piece in accelerating DX on construction sites.

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

Construction and civil engineering sites are now digitizing at an unprecedented pace. The envisioned future includes the realization of a digital twin where sites and offices, as-built works and digital models are synchronized in real time. If sensors, IoT, and 3D models are linked to enable constant monitoring of construction progress and quality, productivity and safety will improve even further. New technological innovations based on 3D data, such as AI-driven automatic detection and integration with robotic construction, are also anticipated.

As the first step to open up this future, it is important to introduce easy-to-use digital tools on site. Smartphone surveying devices like LRTK greatly lower the barrier to digitalization because of their ease of use. Even without specialized technicians who handle dedicated equipment, site staff themselves can start surveying, inspections, and AR utilization, allowing small sites or teams with limited personnel to quickly experience benefits. The initial investment and training costs are relatively modest, and the ability to leverage existing smartphones is a clear advantage for introduction.

Moreover, LRTK’s all-in-one functionality makes it ideal as an entry point for site DX. It can first be introduced as a high-precision simple surveying tool and then gradually expand into point cloud scanning and AR construction management. Cloud integration enables seamless information sharing with the office, supporting new ways of working such as managing multiple remote sites. Above all, enabling everyone on site to handle 3D data contributes to building a robust organization that does not rely on individual expertise.

The future of sites that LRTK pioneers is a new construction style that blends the experience of skilled workers with digital technology. If the cycle of bringing 3D CAD-designed information fully to the site and feeding site-acquired data back into design and management is established, the productivity and quality of construction projects will dramatically improve. As labor shortages become increasingly severe, the trend of “solving problems with technology rather than relying on people” will accelerate. Adopting easy surveying and construction support tools like LRTK early will be a significant advantage for achieving that future. For all engineers looking to take the first step toward site DX, the fusion with such cutting-edge technologies holds the key to a brighter future.