The Key to On-site Efficiency! Start 3D As-built Management DX with Your Smartphone

Introduction

“Construction management DX,” aimed at improving on-site efficiency and quality, is accelerating. Amid chronic labor shortages and demands for work-style reform, there is a growing movement to review inefficient on-site work using ICT. Among these, the digitalization of as-built management is attracting particular attention. As-built management is the important process of confirming and recording whether the shapes and dimensions of completed structures and land have been constructed according to the design drawings. In public works, it is required to prove that the actual as-built condition conforms to the standards specified by the client (such as municipal governments), and this proof is a prerequisite for passing inspections and handing over the project. In other words, as-built management is the very foundation of construction management and a key to ensuring quality.

At the same time, under the banner of “DX,” the introduction of ICT technologies is progressing, and 3D as-built management you can start with a smartphone is poised to transform sites significantly. By combining a smartphone with 3D point cloud data and RTK positioning, as-built management—which traditionally required much manpower and time—can be dramatically streamlined. This article explains the outline and benefits of 3D as-built management using smartphones. From the challenges of traditional methods to the changes brought by the latest technologies, and the use of a new service that supports sites, LRTK, we provide an easy-to-understand introduction.

This article is useful not only for site supervisors and construction management engineers who work on quality control daily, but also for those promoting ICT in the construction industry and municipal employees who commission works. If you have any interest in on-site DX, please read through to the end.

The Importance of As-built Management and Traditional Challenges

The purpose of as-built management is to confirm that construction was carried out according to the design documents and to correct any deficiencies. Especially in public infrastructure works, the results of as-built management determine the outcome of quality inspections, making it an unavoidable task for site supervisors and construction management engineers. However, there were several challenges with traditional as-built management methods.

\- Inefficiency due to manual measurement: The mainstream method to date involved staff using tape measures, rods, and levels to measure the dimensions of structures point by point and check differences from design values. For example, in road works, after completion the width, thickness, and height of the roadbed would be measured at many locations and checked against standards. This method required a large amount of manpower and time and could only measure a limited number of points, placing a significant burden on the site.

\- Risk of limited measurement points: Manual measurement has a physical limit to how many points can be measured. Dangerous areas where people cannot enter, high places, and buried sections that become invisible cannot be measured adequately, so there is the weakness of being able to measure only “points.” Therefore, it was difficult to comprehensively grasp the entire as-built condition, and slight differences from the design could be overlooked. Even if major dimensions were fine, sections outside the standards could go unnoticed and later be pointed out in inspections as “not matching the drawings,” which is not uncommon.

\- Human errors and missing records: Traditionally, measurement results were noted on-site and then recompiled into drawings or tables back at the office. In this process there is a risk of human error, such as writing numbers incorrectly or forgetting to record them. In busy sites, missing records—for example forgetting to photograph buried items—also tend to occur. Reinforcement or underground buried items that become invisible after completion cannot be certified for quality unless photo records are taken during construction. Discovering missing photos after the fact and having to redo work is a major pressure for site personnel.

As described above, traditional as-built management required significant time and manpower, and suffered from variability in accuracy due to biased measurement points and human errors. In recent years, however, “as-built management using 3D point cloud data” has attracted attention as a trump card to solve these issues.

As-built Management DX Using 3D Point Cloud Data

Advances in surveying technology have made it possible to digitally record real space as a whole with 3D point clouds, and this is beginning to be used in practical work. Point cloud data are numerous measurement points (a collection of points) obtained by laser scanners or photogrammetry and represent space as a dense set of points. Using this, the shape of a construction area can be measured non-contact and over a wide area at once, and dimensions at arbitrary locations can be measured afterward. With the momentum of *i-Construction* promoted by the Ministry of Land, Infrastructure, Transport and Tourism, point cloud measurement for as-built management is becoming the “new normal” in the civil engineering and construction industry.

By leveraging 3D point clouds, even minute unevenness and variations in shape that were previously missed can be captured. Because the entire structure is scanned rather than only key points, quality can be understood in terms of surfaces, enabling comprehensive as-built verification with no omissions. In addition, the acquired data are digital, so information sharing among stakeholders is easy, and progress and quality can be checked remotely via the cloud. This can simplify the need for inspector attendance and reduce the effort involved in organizing as-built drawings and photos.

Moreover, recently these point cloud measurements can be performed easily with a single smartphone. Using the simple LiDAR or high-performance cameras installed in iPhones and iPads, site personnel can now perform 3D scans on the spot. However, a standalone smartphone typically cannot embed the acquired point clouds with precise position information (latitude, longitude, elevation) and its absolute accuracy may be insufficient. This is where solutions that add RTK positioning capability to smartphones come into play.

High-precision As-built Management Achieved with Smartphone + RTK Positioning

RTK stands for “Real Time Kinematic,” a technology that uses GNSS (satellite positioning) to obtain centimeter-level position accuracy in real time. Whereas conventional GPS accuracy is on the order of several meters, using RTK positioning makes it possible to achieve high precision of about 1–2 cm (0.4–0.8 in) horizontally and about 3 cm (1.2 in) vertically. By equipping smartphones with this technology, it has become possible to obtain accurate coordinates instantly on-site.

There are two major benefits of combining a smartphone with RTK. First, surveying work can be completed by a single person without the need for specialized surveying equipment or highly skilled personnel. By measuring control points with a small RTK receiver attached to a smartphone, the as-built condition of the construction area can be checked directly. There is no need to lug heavy tripods or levels; lightweight equipment that fits in a pocket suffices, improving mobility.

Second, the point cloud data and photos acquired are tagged with high-precision position coordinates. This allows the scanned point cloud to be overlaid and analyzed in the drawing coordinate system, making the scanner-measured point cloud itself admissible as evidence for as-built management. Previously, using point cloud data required post-processing for georeferencing, but with RTK-enabled smartphones the data measured on-site can be used immediately as coordinates on GIS or CAD drawings. By enabling the smartphone to function as a full-fledged surveying instrument, the barriers to as-built management are lowered and both speed and accuracy improve dramatically.

Start Smartphone As-built Management with LRTK

A representative service that integrates smartphones, RTK, and point cloud measurement is LRTK. LRTK is a high-precision surveying app for iPhone that, when combined with a dedicated small GNSS receiver, enables all measurements necessary for as-built management with just an iPhone. It includes the following core features.

• Centimeter-class RTK positioning: An amazingly precise positioning function for a smartphone that acquires coordinates of various structures in real time. Level surveying, checking batter boards, and height measurement for as-built verification can all be performed easily by one person.

• 3D point cloud scanning: Makes use of the iPhone’s LiDAR sensor and camera to record site conditions as three-dimensional point cloud data. High-density point clouds allow comprehensive visualization of as-built conditions, preventing oversights. Acquired point clouds are automatically saved with positioning coordinates, enabling later comparison with design data and quantity calculations.

• AR visualization: An augmented reality (AR) function that overlays design models and drawing information onto the real site view. By projecting a 3D model of the completed form on the smartphone screen and comparing it with the structure under construction, as-built deviations can be grasped at a glance. Positioning is automatically aligned using high-precision RTK coordinates, so there is no worry about model drift. This is powerful for explaining work content to clients and for inspections.

• Coordinate navigation (stakeout guidance): When placing stakes or structures at positions specified in design drawings, the smartphone can navigate to target coordinates with on-screen and voice guidance. One person can accurately perform batter board or foundation layout, greatly improving the efficiency of stakeout work.

• Automatic report generation: Recordkeeping is also important in as-built management, and LRTK can auto-generate reports with one button based on measurement results. Documents that used to be compiled manually—such as inspection records and as-built dimension management diagrams—are completed on the spot. Position information, notes, and photos taken on-site are immediately output as PDF reports, eliminating overtime spent creating reports.

• Cloud sharing: Measurement data can be uploaded to the cloud and shared within the team or with stakeholders. Coordinates, point clouds, and photos acquired on site can be checked in real time from office PCs, enabling instant information sharing with remote supervisors or clients. This enables remote supervision where progress and quality can be monitored without traveling to the site.

Effects on the Site and Use Cases

By utilizing the functions above, significant benefits can be gained in various aspects of construction management. Below we summarize concrete effects and use cases, comparing them with traditional methods.

1\. Major reduction in work time (time-saving effect): Because 3D point cloud scanning can capture as-built conditions over a wide area at once, measurement tasks that used to take hours can in some cases be completed in minutes. Automatic report generation dramatically reduces the time spent creating reporting documents. For example, the as-built drawing that used to take half a day to produce can now be completed on-site by scanning and pressing a button. This allows site supervisors to devote time to other important tasks.

2\. Responses to labor shortages and labor saving: With the need for small crews increasing, as-built management that can be completed with a single smartphone is an effective measure against labor shortages. Tasks that previously required two people for surveying (one holding the rod, one measuring) can be done by one person with LRTK. It also promotes multi-skilling—such as heavy equipment operators performing their own surveying—improving personnel allocation efficiency.

3\. Improved quality assurance and inspection pass rates: Because point cloud data allow comprehensive measurement of construction areas, the risk of overlooking out-of-spec sections is reduced. Ongoing checks during construction enable correction before final inspections, leading to higher pass rates and fewer rework instances. Having digital evidence readily available also makes explanations to clients smoother and increases credibility. Situations where inspectors suddenly request additional documents become less stressful, and you can confidently face inspections with “presentable site documents.”

4\. Improved safety: Non-contact point cloud measurement and cloud-based verification also contribute to safety. They reduce direct measurement work in hazardous areas, lowering risks to workers. For example, for tall structures you can obtain shapes by LiDAR scanning from below without climbing to great heights. Also, spending less time on-site reduces risks such as heatstroke and traffic accidents. In safety-first construction management, DX technologies are strong allies.

5\. Smooth communication with clients and stakeholders: Intuitive AR visualization and cloud-based information sharing facilitate communication with clients and other departments. Traditionally, completion was explained with drawings and photos, but showing a 3D model on the spot makes it instantly clear. For example, when explaining as-built conditions for a revetment project, overlaying the design BIM model on a tablet helps the client easily visualize the finished form. Holding meetings while all stakeholders share the same data reduces troubles caused by differences in understanding.

As shown above, introducing smartphone + 3D as-built management brings diverse benefits. You can achieve construction management that is “more accurate, faster, safer, and labor-saving,” reducing the burden on site personnel. In fact, major construction companies are actively adopting 3D as-built management, preparing internal manuals and training technicians. In one demonstration, ground-based laser scanners and design BIM data were used to verify the as-built of piles and concrete structures, achieving significant reductions in rework and more efficient inspection procedures. Some local governments also provide subsidy programs to support ICT adoption, making it easier to try these advanced technologies on site. Now is truly an excellent time to step into as-built management DX. As DX accelerates across the industry, it is important for those in charge of sites to get early exposure to digital technologies.

Conclusion: Start On-site DX with Your Smartphone

As-built management is a critical task that determines the quality of construction management, and new technologies now enable unprecedented efficiency and sophistication. Solutions that combine smartphones, RTK, and point cloud scanning allow everyone from site managers to young engineers to perform precise surveying easily and promote as-built management DX. To gain trust from clients and to reduce the burden on site supervisors themselves, why not take the first step toward digitalization?

For example, LRTK lets you perform high-precision simple surveying with just a smartphone, without complicated setup or expert knowledge. Embrace the latest technologies and start “3D As-built Management DX” at your site from tomorrow. You will surely be surprised by the results. Experience the future of construction management for yourself.