Visualizing Buried Utilities with High-Precision Positioning × AR to Reduce Construction Risks

Table of contents

• Introduction

• Challenges of Buried Utilities and Construction Risks

• Traditional Methods for Locating Buried Utilities and Their Issues

• What It Means to Visualize Buried Utilities with AR

• Use of High-Precision Positioning Technology (RTK-GNSS)

• Benefits of AR Visualization of Buried Utilities

• Field Case Studies and Future Outlook

• Easy High-Precision AR Introduction via LRTK for Simple Surveying

• FAQ

Introduction

Various infrastructure facilities such as water pipes, sewer pipes, gas pipes, power cables, and communication cables are buried beneath the ground at construction sites. If these buried utilities are accidentally damaged during work such as excavation or pile driving, there is a danger of serious accidents including gas leaks leading to explosions or fires, water outages or blackouts, and large-scale communication failures. In fact, more than 100 incidents of damage to buried utilities are reported domestically each year, and some years see around 150 incidents. Ensuring safety and preventing construction mistakes remain major challenges for contractors and clients.

To prevent accidents caused by buried utilities, it is essential to accurately know in advance “what is buried where” under the worksite. However, because the underground is invisible, in the past workers had no choice but to rely on drawings and recorded location information for buried utilities. Old drawings may not match actual positions, and there may be pipes that were not updated after modifications. Methods using metal detectors or ground-penetrating radar are available to search for buried objects, but they require specialized equipment and effort and do not guarantee 100% detection. As a result, on-site teams often have to proceed with excavation cautiously based on experience—such as “the gas pipe should be around here”—and less experienced workers face higher risk of mistakes.

In recent years, AR (Augmented Reality) technology that “visualizes” buried utilities has attracted attention. AR overlays CG information onto camera images on smartphones or tablets. Using AR, the positions of pipes and cables hidden underground can be displayed on a device screen as if by X-ray vision. For example, when a worker points a smartphone, a water pipe buried under the road could be shown as a blue line. Making the invisible “visible” enables safer construction planning that avoids buried utilities, and gives heavy equipment operators and workers greater confidence. In addition, AR displays can improve efficiency during post-construction infrastructure inspections by allowing quick verification of underground equipment locations. The use of AR technology is therefore expected to help prevent construction mistakes and improve inspection accuracy, becoming a valuable ally for all stakeholders. This article explains in detail the mechanism and benefits of buried-utility visualization using high-precision positioning × AR and points to consider when introducing it. At the end of the article, we also introduce a method using a new technology called “LRTK” that enables centimeter-level positioning easily for anyone.

Challenges of Buried Utilities and Construction Risks

In Japan, much of the buried infrastructure was installed after the high economic growth period, and in addition to the risk of deterioration-related failures, accidental damage during construction still occurs. In the 1980s, more than 300 incidents of buried utility damage occurred annually, but subsequent strengthened measures temporarily reduced that to below 100 cases. However, in recent years the number has remained around 150 per year, and unfortunately it has not reached zero. For example, if a gas pipe is accidentally damaged, the surrounding area is exposed to the risk of gas leakage and explosion, work is suspended, and recovery and compensation require enormous effort and cost. For contractors, this can be a devastating blow to credibility, and for clients and managers it is a serious headache. Thus, incidents of damage to buried utilities remain a major risk at construction sites.

Traditional Methods for Locating Buried Utilities and Their Issues

To prevent accidents, various checks have long been performed before construction begins. Before starting excavation, contractors first obtain drawings of buried pipes and cables (such as buried-utility maps or owner piping diagrams) from relevant parties to understand what is buried underground. When necessary, buried-object detection devices such as metal detectors or ground-penetrating radar are used to examine the actual positions of pipes and cables beneath the ground. For critical gas pipes or communication cables, it is common to request the presence of the utility operator to jointly confirm locations on-site. Confirmed utility routes are marked on the ground with spray paint or indicated with wooden stakes or signs to alert heavy-equipment operators.

However, it is not easy to completely understand underground conditions using only these conventional methods, and the reality is that on-site work is often carried out with constant concern. The main issues are summarized below.

• Unreliability of drawing information: Paper drawings and ledger information do not always accurately reflect current conditions. Older infrastructure is more likely to have discrepancies between recorded positions and actual burial locations, and some cases are not updated after modifications. There are many cases where unexpected cables are discovered at sites where digging was judged safe based on drawings, causing near-miss incidents.

• Difficulty in pinpointing locations on site: Even when drawings show coordinates or dimensions, accurately translating that information to a specific point outdoors requires surveying knowledge and effort. Recreating drawing positions on site is not easy for non-experts, which often results in excavation based on intuition and experience.

• Limitations of buried-object detection: Pre-investigation using detection devices is not万能. There are targets that are hard to detect with equipment, such as resin pipes buried deep under concrete. Completely identifying all buried utilities would require enormous time and effort and is practically difficult.

• Human error and communication mistakes: Because people conduct these processes, human errors such as overlooking drawings, marking mistakes, or failures in information sharing cannot be eliminated. Even if markings are made, accidents cannot be prevented unless every worker is informed, and small misunderstandings can lead to major mistakes.

Because of these gaps and limitations in traditional verification methods, new approaches that allow more intuitive and reliable understanding of buried utilities were needed.

What It Means to Visualize Buried Utilities with AR

An approach that has emerged to address these issues uses AR (Augmented Reality) technology. By overlaying drawing data and other CG information onto the camera image of a smartphone or tablet, you can “visualize” underground conditions on the spot. Design lines, boundary lines, and the positions of buried pipes that were previously only checkable on paper drawings can be displayed over the real-world site in AR. For example, when pointing a tablet, virtual lines or markers appear on the ground so that the route of buried pipes seems to float up as if you were wearing X-ray glasses.

The greatest advantage of AR display is that it provides visual information that workers can intuitively understand. There is no need to mentally interpret drawings and map them to the site; by simply pointing a device, a red line can instantly show “areas beyond which you must not dig,” making safe boundaries obvious at a glance. Tasks that previously relied on the intuition of experienced workers become visually accessible to anyone using AR. Even inexperienced operators can operate heavy machinery accurately within designated areas by following virtual guidelines displayed on-screen, without physical stakes.

Furthermore, AR enables real-time information sharing. If multiple people view the AR image displayed on-site at the same time, site managers and operators can share the same image. Remote headquarters staff or design personnel can also understand the situation and give instructions without visiting the site by receiving photos or videos of the AR view. In this way, AR visualization not only improves readability but also serves as a powerful on-site communication tool.

Use of High-Precision Positioning Technology (RTK-GNSS)

To make AR technology practical on-site, ensuring display accuracy is critically important. However, GPS built into typical smartphones and tablets can often have horizontal errors of several meters. If buried utilities are displayed in AR with such inaccuracies, the overlays would be too far off from actual pipe locations to be useful for safety checks. Also, conventional outdoor AR systems required recognizing the ground plane in the camera image for alignment or placing artificial markers at arbitrary points for initial calibration. As users walk around, a phenomenon called drift—where the displayed position gradually shifts—often occurs, and repeatedly placing markers for calibration across wide outdoor sites is impractical. Applying traditional AR to surveying or layout tasks that require millimeter- to centimeter-level precision was therefore difficult.

The key to solving this problem is combining AR displays with the high-precision positioning technology RTK-GNSS (Real-Time Kinematic GNSS). RTK satellite positioning dramatically improves GPS accuracy by using correction information from a reference station in real time. By receiving correction signals from reference station data over the internet or Japan’s quasi-zenith satellite “Michibiki” through a centimeter-level positioning augmentation service (CLAS) with a dedicated high-precision GNSS receiver connected to a smartphone, the smartphone can determine its position with about 1–2 cm (0.4–0.8 in) error. This level of high-precision positioning, several orders of magnitude better than the conventional meter-level accuracy, can be achieved with palm-sized equipment.

Moreover, recent smartphones have evolved to include, in addition to camera images and IMUs (inertial measurement units) for position tracking, built-in compact LiDAR (optical distance sensors) in some models. These can scan the surrounding environment in real time to build a 3D spatial map, enabling stable overlay of virtual objects in real space and natural occlusion where virtual objects are properly hidden behind physical ones. By combining these advances in AR platforms with RTK-GNSS’s centimeter-level self-positioning, markerless high-precision AR has become practically feasible for the first time.

When a device can accurately determine its position in a global coordinate system via RTK-GNSS, design drawings or GIS pipe routes can be directly linked to the real world. By linking coordinate information included in design data with the device position and orientation obtained from RTK positioning on-site, virtual models of buried pipes or design lines can be displayed precisely at their actual locations. Once the alignment is completed, the virtual model remains fixed in the real world even as the user moves, so there is no worry about the display drifting over time. Without cumbersome initial calibration or marker placement, models appear automatically in the correct position simply by pointing the device. This “no-coordinate-adjustment-needed” AR experience becomes a practical reality on the jobsite. It gives the reassuring sense that points and lines on design drawings have literally manifested on-site, so even at night or in bad weather you can trust the on-screen lines to excavate to the correct location. AR displays with centimeter-level accuracy thus become a reliable tool that fundamentally reduces the risk of damaging buried utilities.

Benefits of AR Visualization of Buried Utilities

Applying high-precision RTK positioning and AR technology on-site brings various benefits to infrastructure inspection and civil engineering work. The main effects are summarized below.

• Prevention of accidents involving buried utilities: By accurately identifying the positions and depths of pipes and cables with AR before excavation, the risk of damage from machine excavation can be greatly reduced. Visualizing invisible hazards like gas pipes and power lines in advance significantly strengthens safety measures and helps move toward “zero accidents” (no incidents).

• Improved efficiency and labor savings: The need to repeatedly compare paper drawings with the site is eliminated; required information can be confirmed on the spot simply by pointing a device. Tasks such as surveying, layout staking, and recording buried pipe positions can be replaced by a single smartphone, enabling reductions in personnel, shorter working times, and cost savings.

• Improved record accuracy: 3D measurement via LiDAR scanning allows digital recording of buried utility positions and shapes to millimeter accuracy. Much more accurate data is stored in the cloud compared to relying on paper drawings or oral tradition, and the information does not degrade over time. This becomes a highly reliable asset record for future maintenance management, improving buried infrastructure management accuracy.

• Advanced maintenance planning and inspection: AR use brings innovation to renewal planning and periodic inspections of aging pipes. By overlaying current 3D data with past repair histories, sections at high risk of deterioration or voiding can be accurately identified. For example, in investigations for road collapse risk areas, displaying void locations found by ground-penetrating radar and sewer deterioration data in AR while marking on-site ensures no dangerous spots are overlooked. Data-driven preventive maintenance planning dramatically improves the efficiency and accuracy of infrastructure management.

• Smoother information sharing and consensus building: Visualized AR information functions as a shared language on-site. In roadworks, where multiple utility operators such as water, gas, and communications are involved, integrating each pipe dataset and displaying them together in AR allows everyone to share the same underground picture during joint inspections. The time-consuming process of comparing paper drawings is reduced, preventing misunderstandings and communication errors. AR also helps explain situations to clients and nearby residents—pointing a smartphone can intuitively show “these are the pipes under this road” and facilitate understanding and cooperation.

• Promotion of on-site DX and technology transfer: Introducing RTK × AR strongly accelerates digital transformation (DX) at construction sites. It aligns with initiatives such as the Ministry of Land, Infrastructure, Transport and Tourism’s *i-Construction*, and the use of ICT and 3D data contributes to productivity improvement and advanced safety management. High-precision positioning work can be performed even without experienced surveyors, enabling labor and personnel savings in sites facing severe workforce shortages. If data-driven construction management that does not rely on veteran “intuition and experience” becomes established, quality issues and rework can be reduced. In the long term, it is expected to contribute to cost reductions across the lifecycle.

In this way, on-site visualization using RTK positioning × AR is a groundbreaking solution that positively affects safety, efficiency, and accuracy. It is particularly powerful in preventing accidents during excavation work.

Field Case Studies and Future Outlook

RTK × AR buried-utility visualization technologies are already being used in real-world sites. Domestically, a startup developed a system that combines an RTK positioning unit with a tablet to display buried pipes in AR on-site. This allows workers to grasp buried-object locations three-dimensionally without spreading drawings or trial excavations, contributing to improved safety and work efficiency. Field trials reported significant benefits, such as completing records of buried pipe work without taking photos or creating CAD drawings, and being able to immediately locate pipes later during re-excavation using the AR display. Workers commented positively, saying “searching for buried utilities that used to rely on intuition can now be done by anyone” and “the operation was intuitive and usable without training,” indicating good on-site acceptance.

Looking overseas, high-precision AR systems for outdoor use are beginning to attract attention as world-first technologies in construction. Systems have appeared that combine high-performance GNSS receivers and AR to overlap 3D design models and real landscapes with centimeter accuracy on a smartphone, allowing complex BIM models and underground utility information to be shared and verified intuitively on-site. Both in Japan and internationally, initiatives for construction DX and smart maintenance using RTK × AR are accelerating, with deployments expanding from bridge works to water and sewer maintenance. Going forward, such high-precision AR technologies are likely to become more generalized and simplified and may become the industry norm. A future where each worker routinely points a smartphone to check design drawings and underground utilities in AR while working is approaching. Without relying on expensive survey equipment or special skills, anyone will be able to handle accurate spatial-coordinate-based information in real time, further driving a productivity revolution in construction and infrastructure sectors.

Easy High-Precision AR Introduction via LRTK for Simple Surveying

Visualization of buried utilities with RTK × AR has great potential to transform infrastructure maintenance and civil engineering sites. By overlaying digital data on the real world with centimeter-level positional accuracy, tasks that once depended on expert experience are shifting to data-driven smart construction. One solution that is attracting attention as an easy-to-use on-site implementation of this advanced technology is LRTK.

LRTK is an integrated system that enables anyone to achieve centimeter-precision positioning and AR visualization using a compact RTK-GNSS receiver attached to a smartphone and a dedicated app. Many common AR surveying tools require prior marker placement or complex initial calibration, but with LRTK you can power on the device, wait a few dozen seconds for RTK to fix, and immediately start high-precision AR. No special calibration work is required, making it extremely easy to use on-site. Cloud integration also allows seamless operations such as downloading design data or point-cloud survey data for AR display on the spot and instantly sharing measured data to the cloud. Designed to be intuitive for users without specialized knowledge, reports indicate that one smartphone per person enabled surveying, layout staking, inspections, photo records, and AR simulation all with a single device.

By leveraging LRTK, sites can dramatically improve productivity and safety without expensive equipment or large teams. In addition to X-ray-style pipe displays, LRTK can be applied to shape verification of structures, construction navigation, and a wide range of other uses, making it a true “all-purpose surveying tool” and a trump card for on-site DX. Surveying firms, municipal civil departments, and construction contractors can adopt this cutting-edge RTK × AR technology to step into a new era of smart infrastructure inspection. For product information and case studies, see the [LRTK official site](https://www.lrtk.lefixea.com/). Please consider evolving your site to the next stage with LRTK.

FAQ

Q: What is AR display of buried utilities? A: Using AR (Augmented Reality) technology, the positions of pipes and cables buried underground are made visible through a camera. When you point a smartphone at the ground, virtual pipe models are overlaid on the real image, allowing you to check the underground piping as if you were seeing through the ground.

Q: Why is high-precision positioning necessary to display buried utilities in AR? A: To accurately overlay virtual models on actual buried positions, the smartphone’s position and orientation must be known to the centimeter level. Standard GPS has errors of several meters, causing AR pipe displays to be misaligned and preventing accurate “X-ray” visualization. By using the high-precision RTK-GNSS positioning technology, a smartphone’s position can be determined within a few cm of error, allowing virtual pipes to align precisely with their real-world locations.

Q: How are buried utility location data obtained? A: To display buried utilities in AR, you must first acquire 3D data of the pipe positions. For new pipes, three-dimensional records are taken by LiDAR scanning with a smartphone and RTK positioning before backfilling. For existing utilities, you can create 3D models by linking past drawing information with current coordinates measured by RTK, or import point-cloud data derived from ground-penetrating radar results to prepare underground data for AR display.

Q: Can I see through the ground with only a smartphone? A: Yes. By combining a smartphone with a small RTK-GNSS receiver, this is possible. Using the smartphone’s built-in camera, IMU, and LiDAR for AR functions together with an external RTK positioning module to obtain centimeter-level position information, you can accurately display underground pipe locations on a smartphone screen without special goggles or large equipment.

Q: What is LRTK? A: LRTK is a solution that enables anyone to easily perform high-precision positioning and AR visualization of buried pipes using a smartphone. It consists of a lightweight RTK-GNSS module that attaches to the phone and a dedicated app, allowing you to display and survey buried-pipe 3D data on-site without complex settings or special markers. For more details, visit the [LRTK official site](https://www.lrtk.lefixea.com/).