AR Inspections in 3 Minutes: Benefits and Implementation Steps for As-Built Inspections

Table of Contents

• What is AR inspection? (A new form of as-built inspection)

• Benefits brought by AR inspection

• Steps to introduce AR inspection

• Simple surveying and AR inspection enabled by LRTK

• Frequently Asked Questions

What is AR inspection? (A new form of as-built inspection)

“As-built inspection” is the quality-control process in civil engineering and construction that verifies whether completed structures and terrain have been constructed according to the design drawings. Traditionally, as-built verification has been performed using surveying instruments such as total stations (TS) and levels: heights and thicknesses are measured point by point on site, then personnel return to the office to compare measurements with design drawings and determine pass/fail. This method tends to introduce time lags between on-site measurement and problem detection, and work can progress during that lag, causing rework. Accurate measurement and judgment also require skilled survey technicians, and many tasks are performed by two-person teams; in sites facing labor shortages and an aging workforce, this becomes an inefficient process.

A promising solution gaining attention in recent years to address these issues is AR (Augmented Reality) technology. AR overlays three-dimensional digital information (models, drawing data, etc.) onto real-world imagery. While it was once an advanced experiment, improvements in smartphone and tablet performance have made AR usable in everyday construction management.

Modern smartphones and tablets are equipped with high-performance cameras and LiDAR sensors. Using dedicated AR apps that leverage these capabilities, as-built conditions can be intuitively checked on site. With industry-wide DX efforts such as the Ministry of Land, Infrastructure, Transport and Tourism’s i-Construction (https://www.mlit.go.jp/tec/i-construction/), the introduction of AR into as-built inspections is increasingly expected as a powerful solution to simultaneously improve field efficiency and quality.

Benefits brought by AR inspection

Applying AR technology to as-built inspections brings various benefits not available with traditional methods.

• Real-time problem detection: With AR, construction defects and deviations from design can be detected on the spot and corrective actions taken immediately. For example, if areas with insufficient pavement thickness or inadequate slope are color-coded on the AR screen right after construction, additional work or milling can be performed the same day. Because you can run the PDCA cycle on site, rework is minimized and leaving quality defects unaddressed is prevented.

• Shorter work time and labor savings: Conventional inspections, which required measuring points one by one with paper drawings and surveying instruments, are replaced by the intuitive action of holding up a smartphone or tablet and overlaying the digital model with AR. Since a wide area of as-built conditions can be visualized at once, inspections that used to take days can be dramatically sped up. Also, measurement and verification can be completed by a single person, reducing manpower coordination and saving labor.

• Responding to workforce shortages: Site personnel can evaluate as-built conditions themselves without relying on specialized surveyors or veteran technicians. AR app operation is simple—follow on-screen instructions to complete measurement and verification—so no special expertise is required. This prevents work from becoming person-dependent, enabling less experienced staff to participate in measurement and checks, which makes it easier to cope with labor shortages on site.

• Cost reduction: AR using smartphones or tablets eliminates the need to purchase expensive total stations or high-precision GNSS survey systems. Dedicated surveying instruments can require initial investments of several million yen, but recently it has become possible to achieve centimeter-level positioning accuracy at low cost by combining common mobile devices with relatively inexpensive GNSS receivers. Maintenance and transportation costs for equipment can also be reduced.

• Improved measurement accuracy and reliability: Using AR reduces risks of manual measurement errors and recording mistakes. There is no need to later transcribe numbers noted on site; digital data can be compared directly, eliminating human error. Furthermore, when combined with high-precision positioning technologies such as RTK-GNSS, measurements can consistently match public coordinate systems with centimeter-level positioning accuracy (cm level accuracy, half-inch accuracy), allowing more reliable as-built verification than before.

• Streamlined recordkeeping and reporting: AR enables intuitive visual records of as-built inspections, making report creation easier. For example, AR screen screenshots or differential heatmap images can be attached directly to inspection reports, making them far easier to understand than traditional reports listing only numbers. In fact, Ministry of Land, Infrastructure, Transport and Tourism field demonstrations have confirmed that AR can simplify submission documents such as as-built drawings. Because records are retained as digital data, later review is easy, reducing reporting burdens.

• Better consensus-building and communication: AR visualization is effective for information sharing with stakeholders both inside and outside the site, including clients. For example, holding up a tablet to overlay the completed image onto the actual site makes explanations during client inspections far smoother. Visually presenting as-built status on AR reduces misunderstandings and can allow parties to agree on corrective areas on the spot. According to MLIT surveys, AR technology is beginning to be used not only for construction management but also for pre-construction resident briefings and meetings with subcontractors. Improved communication between site, office, and client contributes to overall operational efficiency.

Steps to introduce AR inspection

To establish AR-based as-built inspections on site and maximize their effectiveness, careful planning during introduction is important. Below are steps to successfully implement AR inspections.

• Ensure high-precision alignment: To overlay digital information correctly with AR, precise coordinate alignment with the real world is essential. On large sites and long structures, a few centimeters (a few inches) of misalignment can lead to significant errors, so ensure centimeter-level positioning accuracy (cm level accuracy, half-inch accuracy) using RTK GNSS or calibration with known control points. An RTK-compatible AR system allows you to project models without the hassle of placing physical reference markers on site, and provides stable AR display without model drift when moving.

• Prepare 3D design data: AR inspections require 3D design data (BIM/CIM models, etc.) for comparison. If 3D data are not available, create simple 3D models from 2D drawings or convert current conditions to point-cloud data via photogrammetry or LiDAR scanning to prepare digital data for comparison. With the trend toward CIM promoted by MLIT, the provision of 3D models in many public works is expected to become standard. It’s important to get your team accustomed to handling 3D data early.

• Integrate into operational workflows: To make AR checks part of routine work rather than a one-off demo, clearly define when, who, and at what timing AR will be used. For example, include in construction plans and inspection procedures that “AR is used for rebar inspection before concrete placement” or “AR checks finish after each embankment completion.” Also decide in advance how AR-checked results will be recorded and reflected in reports. Using a system that automatically attaches date/time and location information to AR screenshots and saves them to the cloud makes it convenient to use them as evidence in inspection records. By integrating AR into existing quality management flows, it becomes a tool that everyone on site uses routinely.

• Train site staff: To reduce resistance to new technology, it’s essential that site staff understand how to use AR and its benefits. Start with IT-savvy personnel running small-scale trials of AR inspections. Demonstrating actual use—letting staff see that “anyone could measure by following the on-screen instructions”—is important. Modern AR apps are intuitive and can be learned in short training sessions without specialized knowledge. Share operation procedures through internal training and on-the-job coaching, and present examples that show benefits to veterans to ensure smooth acceptance.

• Phased introduction and effect verification: Rather than deploying AR across all sites and processes at once, begin with trial implementations on selected sites or processes to verify effectiveness and uncover issues. For example, use AR measurement on a specific section to collect data on how much work time was reduced and how much measurement errors decreased compared to traditional methods; this helps gain internal and external buy-in. Start small to accumulate know-how; if problems in equipment handling or accuracy verification are found, improve them before full rollout. Prepare internal manuals and checklists based on trial results to make future deployments smoother.

• Use cloud services: By using cloud services integrated with AR apps, measurement data, point-cloud models, and site photos can be automatically saved and shared in the cloud. Real-time sharing between site and office enables remote checking of as-built conditions on AR screens. With everyone on the team able to view and comment on the latest data in the cloud, instructions for corrective actions or requests for additional investigation can be issued quickly. Data history stored in the cloud can be referenced in future projects or used as evidence if troubles occur. When introducing AR, leverage cloud connectivity as much as possible for unified data management and smooth information sharing.

Simple surveying and AR inspection enabled by LRTK

LRTK has been attracting attention as a solution that makes AR as-built inspections more accessible and higher in accuracy. LRTK is a latest tool that allows centimeter-level high-precision positioning using RTK simply by attaching a small GNSS receiver to a smartphone; it aims to enable surveying tasks that previously required specialized equipment and skilled operators to be completed by a single person.

LRTK also integrates seamlessly with AR functionality. Using position information from the high-precision GNSS, 2D/3D design data can be overlaid precisely on site without complex alignment work, and the model will not drift when moving. For example, walking around the site with a tablet in hand can accurately overlay virtual stake positions from the design model onto the actual ground, allowing target coordinates to be confirmed at a glance even from a distance. It is also possible to automatically overlay the acquired as-built point cloud and the design model on LRTK’s cloud for differential comparison to instantly check whether work has been carried out according to plan.

LRTK provides a cloud platform as well; data measured and scanned on site are synchronized to the cloud in real time. Team members can remotely view the latest 3D point clouds and survey data from office PCs, enabling site and office to jointly verify as-built conditions. On the cloud, distance, area, and volume measurements, and location-tagged photo management can be performed with one click. This enables collaboration across site and office and dramatically improves the efficiency of as-built inspections.

Additionally, LRTK offers diverse functions beyond as-built management, such as a “coordinate navigator” that guides a single worker to stake positions, functions to calculate embankment volumes from point clouds obtained by LiDAR scanners, and cloud-sharing of geotagged photos. In other words, processes that traditionally required multiple dedicated devices—from surveying to verification, recording, and as-built inspection—are designed to be completed with a single smartphone. Data collected on site can also be used or delivered in formats compliant with MLIT’s as-built management guidelines, and many construction companies are already adopting LRTK to achieve both labor savings and quality improvements.

By using the smartphone-surveying + AR system LRTK, anyone can easily perform high-precision as-built checks and overcome various constraints related to surveying and inspection. Even sites suffering from labor shortages can achieve reduced work time, fewer human errors, and improved stakeholder communication by equipping each worker with a smart surveying tool and leveraging AR. These technological innovations strongly support DX in construction sites and are fundamentally changing as-built management. The key to successful AR inspection is to incorporate such advanced tools effectively to boost overall site productivity. Make the latest technology your ally and let “AR inspection” demonstrate its full value at your sites.

Frequently Asked Questions

Q: What do I need to start as-built AR inspections? A: Basically, you need an AR-capable smartphone or tablet, a GNSS receiver to improve positioning accuracy, and a compatible AR surveying app. Modern iOS/Android devices have cameras and sensors well suited to AR use. If centimeter-level accuracy is required, combine a Bluetooth-connected compact GNSS rover for RTK positioning (e.g., an LRTK device that can be attached to a smartphone). Also prepare digital data for comparison such as 3D design models or point clouds. With these set up, you can immediately try AR-based as-built inspections on site.

Q: Can I trust the accuracy of AR as-built inspections? A: Yes, if operated properly, high reliability can be achieved. Systems using GNSS RTK corrections can realize positioning accuracy with errors of a few centimeters (a few inches) in both plan and elevation, which falls within the accuracy range typically required for as-built verification. When confirming deviations on AR, heatmap displays and the like can provide quantitative information such as “which point is how many centimeters higher/lower.” It is important to align site control points and coordinates in advance and, when necessary, verify key points using traditional methods. Doing so will allow AR inspection results to be trusted with sufficient basis.

Q: Can AR be used on sites without 3D design models? A: Even without 3D models, AR can still be used with some ingenuity. There are apps that overlay 2D drawing data (CAD data, etc.) in AR space to visualize major lines and positional relationships on site. If the finished shape is relatively simple, a simple method is to pre-mark key dimensions on site and overlay them onto AR-captured images. However, AR’s full potential is realized when 3D models are available. Since creation of CIM models (3D models) is increasing especially for public works, request 3D data from clients or consider creating simple models in-house. Another approach is to use measured as-built data (point clouds) and compare them with design information.

Q: Are AR inspection results accepted as official inspection records? A: At present, relying solely on AR as the exclusive basis for official inspections is still in early stages, but acceptance is gradually growing. MLIT conducted field demonstrations in fiscal 2023 and confirmed that AR can enable omission of certain as-built documents. Currently, it is often required to use traditional records (verification drawings, photo logs) in combination, but submitting AR verification results as supporting materials can help inspectors understand the situation more easily. For example, showing an AR heatmap indicating “this point is ◯ cm higher/lower than the design” conveys the information more intuitively than a table of numbers. In the future, there is a growing possibility that data acquired by AR itself will be recognized as official deliverables.

Q: I’m worried whether everyone on site can handle these technologies. A: AR construction support tools are becoming more user-friendly each year, and basic operations are not difficult. Many adopting companies report that staff from young to experienced can become able to use them after short training. If concerns remain, have an experienced operator demonstrate on site first while others observe. People tend to engage positively once they see the benefits with their own eyes; when they feel “it really is faster” and “it’s easy to understand,” resistance diminishes. Recent AR apps support Japanese and have solid support structures, so help is available when needed. ICT in construction will increasingly become essential, so take a steady, phased approach to gaining familiarity.

Q: Do I need dedicated AR glasses? A: At present, most practical use cases can be covered by smartphones and tablets. See-through AR smart glasses have appeared, but they are very expensive and pose challenges such as difficulty using them with safety helmets. Smartphones and tablets can be easily used on site in dustproof/waterproof cases, and operation is simple via touchscreen. Device resolution and processing power continue to improve, and handheld devices provide adequate visibility and performance for AR tasks. If glasses become lightweight and affordable in the future, their use may expand, but currently handheld devices are the most realistic and cost-effective option for AR inspections.