Projecting Drawings onto the Site with AR! As-built Management DX Transforming Construction Management

Comparing design drawings with the finished site and asking, “Is this really built according to the design?”—this is a task that engineers involved in construction management face daily. But now, that conventional approach is being transformed by AR (Augmented Reality) technology. For example, by pointing a smartphone or tablet, you can overlay design drawings or 3D models at actual scale onto the real scene and intuitively verify on the spot whether the constructed elements match the plan. This dramatically improves the speed and reliability of quality checks and strongly supports DX (digital transformation) in construction management.

This article explains the changes that AR-driven as-built management DX brings to the field for engineers responsible for as-built and construction management. We explore the as-built management support features and implementation effects of the latest technology LRTK, which enables high-precision surveying with a smartphone, the practical site operations enabled by AR integration, and the compatibility with the Ministry of Land, Infrastructure, Transport and Tourism’s as-built management guidelines, outlining a new form of construction management.

What is as-built management? Conventional construction management methods and their challenges

First, let’s briefly review what as-built management is. As-built management is a quality assurance process in civil engineering and construction that measures and verifies whether completed structures and terrains are finished with the shapes and dimensions specified in the design drawings. During and after construction, height, thickness, slope, and other parameters are measured at specified checkpoints, and deviations from design values are examined to determine pass/fail. As-built management is a key pillar of construction management alongside schedule and quality control, and it is indispensable for proving that the finished work conforms to the specification values set by the client.

However, conventional as-built management methods required significant labor and time and had limited coverage. Typical workflows—using general surveying tools (levels, total stations, etc.) and tapes to manually measure and record each point, then returning to the office to compare with drawings—are analog processes that depend on skilled technicians and manpower. The construction industry is currently facing severe labor shortages and an aging workforce, making it a major challenge to ensure quality efficiently with limited personnel. Paper drawings and manual management also meant that measured data could not be immediately utilized on site, causing time lags in detecting errors and issuing correction instructions.

The main issues typically pointed out with traditional as-built management can be summarized as follows:

• Long working hours: Staff had to measure painstakingly point by point using levels or tapes, so when sites were large or the number of checkpoints was high, it took a great deal of time. It was not uncommon for several days to pass before measurement results were compiled and verified against drawings.

• Dependence on manpower and skilled technicians: Accurate measurement and evaluation required experienced surveyors and other technicians, and many tasks required two-person teams. With the advancing shortage of personnel, securing sufficient staff for each site imposed a large burden.

• High equipment costs: High-precision surveying instruments such as total stations (TS) and RTK-GNSS receivers require initial investments on the order of millions of yen. For small companies or sole proprietors, the barrier to entry is high, and maintenance and theft risks were also concerns.

• Measurement errors and recording mistakes: Manual surveying can introduce small cumulative errors with each measurement, and human error can occur when transcribing memo numbers onto drawings. There is also the risk of discovering misentries later and having to re-measure.

• Time-consuming report creation: Preparing as-built drawings and reports based on measurement results for submission to the client was also a burden for site personnel. Time spent organizing photos and plotting on drawings sometimes left insufficient time for core quality analysis.

• Delayed defect detection: Even if there were issues such as insufficient thickness or incorrect slopes after construction, conventional methods often could not detect them immediately on site; they were often discovered after data had been taken back and drawn up into drawings the next day or later. By the time a problem was discovered, concrete might have already hardened or heavy machinery might have been removed, resulting in extra rework labor and costs.

As shown above, traditional as-built management faced mounting challenges such as insufficient efficiency and immediacy, and burdens in terms of personnel and cost. For example, in buried piping work, a complex process was necessary—photographing and surveying the piping before backfilling, then creating CAD drawings afterward. Such procedures delayed on-site situation awareness and record-keeping, and even the data obtained was sometimes used only as attachments to reports rather than being fully utilized. It goes without saying that a new method that enables real-time, accurate, and intuitive understanding of as-built conditions was needed.

DX in construction sites and expectations for AR technology

Against this backdrop, the push for DX (digitalization and productivity improvement) across the construction industry is accelerating. Since around 2016, the Ministry of Land, Infrastructure, Transport and Tourism has promoted a policy called i-Construction to support industry-wide adoption of ICT technologies in surveying and construction management. Digital construction practices such as drone aerial 3D surveying and machine guidance/machine control for construction equipment are becoming more widespread. In as-built management as well, a shift toward using three-dimensional measurement technologies instead of traditional layout and level surveying has emerged, and the ministry has formulated a “Guideline for As-built Management Using 3D Measurement Technology (draft)” to promote on-site application. In March 2025 (Reiwa 7), supervisory and inspection guidelines for as-built management were revised simultaneously for each work type—earthworks, paving, slope work, structures, etc.—and as-built management using digital measurement was standardized in earnest.

The new guidelines recommend accurately capturing as-built conditions in surface form using RTK-GNSS, terrestrial/UAV laser scanners, photogrammetry, and other methods, and judging conformity by comparing with design data. For example, advanced inspections that automatically perform difference analysis by overlaying acquired 3D point cloud data onto the design model and visualize the current state with color-coded heat maps have become possible. Notably, the practical use of AR technology on sites has also become realistic. Thanks to dramatic improvements in the performance of devices such as smartphones and tablets, AR—once mostly at the experimental stage—has reached the point where it can be practically used in everyday construction management. The latest iPhones and iPads, in particular, include high-performance cameras and LiDAR sensors, and with dedicated apps, it has become possible to overlay design data onto construction results on-site and intuitively confirm as-built conditions.

The government is also supportive of new technology use; in FY2024 it issued a memorandum saying that “when a contractor proposes simplification and efficiency using 3D models or AR, etc., it should be actively trialed in place of conventional standards.” In some cases, the memorandum even states that “if as-built measurement results projected on-site using AR are used to judge conformity, submission of conventional as-built management forms may be unnecessary,” indicating that as-built management methods using AR are gradually being officially recognized. Against this background, AR technology—which can achieve both labor-saving on site and improved quality—is attracting strong expectations as a key enabler of as-built management DX.

What is LRTK: a new technology that turns a smartphone into a high-precision surveying instrument

So what is needed to easily use AR on sites? The key is an innovative solution called LRTK (LRTK). LRTK is a technology that converts a smartphone into a centimeter-level surveying instrument (half-inch accuracy) by attaching a compact high-precision GNSS receiver device to the phone. Normally, a smartphone’s built-in GPS has errors on the order of several meters, but attaching an LRTK device reduces the error to within a few centimeters—an order-of-magnitude improvement. This is made possible by using a positioning method called RTK (Real Time Kinematic), where real-time correction information from a base station is received to achieve high-precision positioning. The smartphone and LRTK device connect via Bluetooth or similar methods; the device’s high-sensitivity GNSS antenna provides positioning data that the smartphone app can use.

<small>*Note:* RTK-GNSS is a positioning method that enhances global navigation satellite system (GNSS) positioning (using multiple satellites such as U.S. GPS and Japan’s Michibiki) by adding real-time corrections to achieve high precision. LRTK is designed to make this RTK positioning easily accessible to anyone and supports the centimeter-level positioning augmentation service (CLAS) provided by Japan’s Quasi-Zenith Satellite System (Michibiki) (half-inch accuracy).</small>

Simply attaching such an LRTK device to a smartphone creates an environment where anyone can easily perform high-precision surveying and as-built management alone. There is no need to carry heavy tripods or specialized equipment; you can survey and inspect with just a smartphone in hand, greatly improving on-site mobility. In fact, with LRTK you can simultaneously acquire 3D point cloud data using the smartphone’s camera or LiDAR and seamlessly upload the acquired point cloud to the cloud to compare with design data. When you take photos, high-precision position coordinates, timestamps, and memo information are automatically recorded, dramatically improving the efficiency of collecting as-built management evidence.

The LRTK series includes several products for different uses, with a representative model being the smartphone-mounted “LRTK Phone.” This compact device fits in one hand and integrates the battery and antenna, making it practical for a day of surveying on site. The impact of enabling centimeter-class positioning that previously required specialized equipment and experts to be performed by “a single smartphone” is significant—it is truly a game changer for the field. In practice, LRTK has been adopted across a wide range of civil engineering, construction, surveying, and infrastructure management sites, including damage surveys after the Noto Peninsula earthquake, and it is attracting attention as a next-generation construction management tool that complies with the Ministry of Land, Infrastructure, Transport and Tourism’s 3D as-built management standards.

Overlay drawings on the site with AR! A new form of as-built management

Combining LRTK’s high-precision positioning with AR dramatically advances on-site verification for construction management. Because you can overlay design data (drawings and 3D models) onto actual construction results on the smartphone screen, tasks that were previously performed in the office by comparing drawings can now be intuitively done on-site. Here are some key use cases of as-built management using AR.

• AR projection of design models: 3D design models (BIM/CIM models) of buildings and civil structures can be displayed at full scale directly in the site scenery. For example, displaying a model of the completed structure in AR on the ground before construction allows stakeholders to share the image of the finished as-built in advance or use it as a guide for layout. Even during construction, you can compare the placement of structural members such as columns and walls with the design on site. Differences from the anticipated finished image that are hard to grasp from paper drawings or numerical data become immediately apparent as life-size visuals in AR.

• Visualization of as-built heat maps: A heat map shows differences between design and as-built by color-coding deviations. By automatically matching 3D point cloud data acquired with LRTK against the design data in the cloud, you can visualize discrepancies—high areas red, low areas blue, etc. If you import this heat map data into a smartphone and display it in AR over the site scene, you can instantly see which locations are excessively higher than the design. For example, in embankment work, this helps evaluate finished heights across the surface and immediately correct defective areas, speeding up the PDCA cycle. Previously, even when viewing heat maps on paper or a PC, you had to stake out measurement points and mark them to identify problem locations in the field, but with AR you can confirm positions directly through the camera and immediately begin remedial work on site.

• AR visualization of buried objects: As-built conditions of underground structures and piping—things you cannot see—can be visualized as if through a see-through view using AR. For example, in sewer pipe installation, if you scan pipe locations with an iPhone + LRTK before backfilling and store high-precision data in the cloud, you can later display that pipe’s 3D model or alignment line on a smartphone screen even after backfilling. This lets anyone confirm the precise location and depth of piping simply by pointing a smartphone at the surface after paving. It eliminates the need to mark the ground or constantly refer to drawings immediately after burial, enabling even inexperienced workers to intuitively understand buried locations on site, which helps prevent accidental excavation and enhances safety. Such digital as-built data will also be invaluable for future maintenance and renovations.

In this way, the “on-site verification where digital and physical are fused” made possible by LRTK and AR integration offers new experiences and benefits for construction management. Compared with traditional methods that relied solely on paper drawings and lists of numbers, visual understanding deepens markedly, reducing communication losses. Stakeholders—designers, constructors, and clients—can stand on site and view the same AR display to resolve differences in perception on the spot. With cloud data linkage between site and office, it also becomes possible to check construction status or issue instructions remotely. This is the realization of a real-time, two-way on-site operation that can rightly be called “as-built management DX.”

Effects of LRTK introduction and benefits for the site

Introducing LRTK to support AR-based as-built management is expected to deliver the following concrete effects on-site.

• Labor saving and single-person surveying: With a smartphone and LRTK, one person can complete on-site measurement, recording, and verification, greatly reducing the multiple personnel traditionally required. Even less-experienced technicians can operate by following device and app guidance, reducing the burden on veteran technicians and helping to alleviate labor shortages.

• Improved efficiency and immediate inspection: Measurement data is processed immediately via cloud upload or within the app, allowing pass/fail judgments to be made on the spot. Detecting defects immediately after construction and issuing correction instructions prevents rework and schedule delays, accelerating the on-site PDCA cycle. Losses from suspending work while waiting for inspection results are also reduced.

• High-precision, high-quality inspection: Measuring wide areas as point clouds and matching them closely with the design model makes it easier to detect subtle unevenness or dimensional discrepancies that might have been overlooked. Heat maps allow an overall view of quality, addressing variability in construction accuracy that spot measurements alone could not fully capture. As a result, consistent compliance with quality standards is achieved, increasing confidence in client inspections.

• Cost reduction and lighter equipment to carry: You do not need to acquire expensive specialized equipment; a combination of a smartphone and a relatively inexpensive LRTK device suffices, reducing initial investment costs. All equipment can fit in a backpack, lowering the burden of transporting devices to distant sites and reducing theft risk. On-site mobility improves, and the physical burden of surveying and inspection tasks is reduced.

• Data linkage and simplified report creation: Digital measurement data is stored in the cloud and can be used to automatically generate as-built drawings and forms. LRTK cloud services are developing functions to output construction management reports with one click, reducing overtime spent organizing photos and creating tables. Data is saved in formats that can be used for electronic deliverables, contributing to paperless and simplified inspection documentation. Freed from cumbersome paperwork, site technicians can focus on core quality improvement measures.

• Contribution to safety and skills transfer: AR can visualize hazardous areas and work zones to alert heavy equipment operators or help workers confirm safety among themselves. Sharing AR views between young and experienced workers also makes tacit knowledge visible, enabling learning from the same perspective as veterans. AR can be used in site training to simulate construction procedures, making it a promising educational tool. Including these secondary effects, digital technology adoption contributes to work style reform on site and the cultivation of a safety and quality culture.

As described above, AR-based as-built management with LRTK is a solution that balances reductions in time, labor, and cost with improvements in quality and safety. From the site perspective, the sequence of measuring, recording, and checking becomes dramatically easier, bringing more margin and certainty to daily construction management tasks.

Alignment with the Ministry of Land, Infrastructure, Transport and Tourism’s as-built management guidelines for secure operation

When introducing new technologies on site, a common concern is whether the methods are officially accepted. As-built management using AR + LRTK is compatible with the Ministry of Land, Infrastructure, Transport and Tourism’s guidelines and standards. As mentioned earlier, the ministry has set forth guidelines for as-built management using 3D measurement technology and recommends using digital measurement, including RTK-GNSS-based measurements and processes that compare acquired data to design documents to evaluate conformity. LRTK is precisely a tool that makes RTK-GNSS easily usable on site, and using the point clouds and photo data acquired with it to judge as-built conformity aligns with the methods described in the guidelines.

Furthermore, recent trials have opened the door to AR use in inspections. For example, as noted above, notices have begun to allow skipping traditional paperwork submission when AR is used for as-built inspection. This indicates that the government recognizes on-site AR verification as sufficient evidence to replace conventional forms. Therefore, if site personnel use LRTK and AR to inspect and record results and share those results with the client, in some cases the time-consuming tasks of writing measurement points on paper drawings and attaching photos may be eliminated.

Of course, in actual operations, prior consultations with clients and site supervisors and agreements on digital data submission are still necessary, but at least the technical and institutional groundwork is being established. Not only in national government-managed projects but also at prefectural and municipal levels, adoption of 3D as-built management and electronic deliverables is gradually expanding. Concerns like “Will this new method be accepted in inspections?” are diminishing, and the environment for confidently embarking on site DX is taking shape.

Conclusion: The future opened by as-built management DX

Projecting design drawings onto the site with AR and checking as-built conditions on the spot—what once seemed like a dream is now within reach. The combination of LRTK and AR, pioneers of as-built management DX, supports and replaces tasks that once relied on veteran experience with technology, opening a path to a future where anyone can perform efficient, high-quality construction management. This method, which reduces site burdens while guaranteeing quality, offers significant benefits from the perspectives of work-style reform and training young talent.

DX in construction will not happen overnight, but the accumulation of changes on each site will lead to industry-wide transformation. Why not start as-built management DX with a single familiar smartphone? Bringing digital capability and assurance to sites that once struggled with paper drawings and surveying tools—this is becoming the new normal in construction management: projecting drawings onto the site with AR. Site personnel should take this wave and experience firsthand the coexistence of productivity improvement and quality assurance. The future of construction management where digital and real converge is right around the corner.