Preventing Damage to Buried Utilities with AR! Visualize in Advance to Achieve Zero Excavation Accidents

Table of Contents

• Introduction

• Current Situation and Issues of Buried Utility Damage Accidents

• Conventional Methods for Confirming Buried Utilities and Their Problems

• Visualizing Drawings, Boundaries, and Buried Utilities on Site with AR

• Benefits of AR Displaying Drawings, Boundaries, and Buried Utilities

• High-Precision AR Display Realized with RTK-GNSS

• AR Use at Excavation Sites: Visualizing Boundaries and Buried Utilities

• Easy High-Precision AR Introduction with Simple Surveying Using LRTK

• FAQ

Introduction

In excavation work on construction sites, there is always a risk of accidentally damaging buried pipes and cables underground. For example, if a hydraulic excavator (backhoe) severs a gas pipe or power cable while digging, it can lead to a gas leak accident or a large-scale power outage. In fact, in recent years incidents of damage to underground buried utilities have continued to occur, causing serious problems such as impacts on nearby residents, high restoration costs, and safety concerns.

To prevent such excavation accidents, careful prior checks and vigilance are essential. If the positions of buried utilities can be accurately understood and “made visible,” anyone can work with confidence. A highlighted recent approach is using AR (augmented reality) technology to visualize underground buried utilities and boundary lines in advance. This article explains the current situation of buried utility damage accidents and the issues with conventional countermeasures, and clarifies how AR-based on-site display of drawings, boundaries, and buried utilities contributes to accident prevention. We also introduce the latest technologies that make high-precision AR easy to realize and our simple surveying system LRTK, offering tips for achieving “zero excavation accidents.”

Current Situation and Issues of Buried Utility Damage Accidents

At roadworks and land development sites, invisible underground infrastructure constantly poses a potential hazard. In Japan, over 100 incidents of underground buried utility damage are reported each year, and some years see around 150 incidents. The main affected utilities include potable water pipes, sewer pipes, communication cables, power lines, and gas pipes. Water pipe damage accounts for many cases, sometimes about half of incidents in a year. Gas pipe breakages are fewer in number, but if they occur they carry a high risk of gas leakage and fire to the surrounding area and can always lead to serious accidents.

Behind these buried utility damage incidents are cited issues such as insufficient underground utility surveys and prior checks, and failures in information sharing. There are cases in which excavation workers or construction managers operate heavy equipment believing “there should be no buried utilities here,” and end up cutting a cable that was overlooked. Also, even where drawings suggest a location is safe, the actual buried position may differ from what is recorded. Small misperceptions or complacency can lead to major accidents, which is why construction sites are constantly urged to be vigilant. When an accident does occur, delays in construction schedules and impacts on surrounding areas are unavoidable, and the responsible contractor faces loss of social trust and potential compensation liabilities.

To achieve “zero accidents,” measures that eradicate buried utility damage incidents are indispensable. This requires thorough implementation of conventional safety measures (confirming buried utility positions in advance, test excavations by hand, third-party witnessing, etc.) and enhancing the accuracy and reliability of confirmation work by leveraging the latest technologies.

Conventional Methods for Confirming Buried Utilities and Their Problems

Various confirmation tasks have long been carried out on site to prevent accidents. Before starting excavation, the first step is to obtain various buried utility drawings (buried pipeline maps or utility-owner piping diagrams) to understand what is buried underground. When necessary, buried utility detection equipment such as ground-penetrating radar or cable locators is used to investigate the positions of subsurface pipes and cables. If important gas pipelines or communication cables are present, it is common to request attendance from the utility operator (gas company or communications company) to confirm positions together on site. The routes of confirmed buried utilities are often marked on the ground with spray paint or indicated by stakes or signs so heavy equipment operators can easily see them.

However, there are several problems with these conventional methods. First is the unreliability of drawing information. Paper drawings and design plans do not always accurately reflect current conditions. Older infrastructure is more likely to have discrepancies between recorded drawings and actual buried positions, and records may not have been updated after renovation work. There are cases where a location judged safe according to the drawings contains unexpected cables. Second is the difficulty of pinpointing positions on site. Even if coordinates or distances are written numerically on the drawing, translating that accurately to a point outdoors requires surveying knowledge and effort. Unless one is experienced, transferring drawing information to a physical point on the ground is not easy. As a result, decisions sometimes rely on experience-based intuition.

Moreover, detection equipment is not omnipotent. Targets such as pipes under concrete or deep-buried plastic pipes can be difficult for equipment to detect. Fully identifying all buried utilities in advance requires significant time and effort and is often impractical. In addition, coordinating attendance with stakeholders and performing marking work are time-consuming. If there are human errors or communication omissions, markings might not be shared with workers, leaving accident risks. Thus, conventional methods alone are limited, and a more intuitive and reliable support measure has been needed.

Visualizing Drawings, Boundaries, and Buried Utilities on Site with AR

A new approach using AR (augmented reality) technology has emerged. AR overlays CG or text information on the camera view of a smartphone or tablet. Using this, design lines, boundaries, and the positions of underground buried utilities that were previously only checkable on paper drawings can be displayed as AR overlays on the actual site. For example, when viewing the site through a tablet screen, virtual lines and markers appear on the ground. It is as if you are peering underground with X-ray glasses: the routes of pipes buried underground and property boundary lines appear to float in the physical space.

The key point 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; pointing a smartphone reveals at a glance “a gas pipe runs from here onward” or “the allowable excavation range ends at this line.” Tasks that used to rely on a veteran’s intuition can now be judged visually by anyone with AR. Even inexperienced operators can accurately perform excavation within safe limits by operating heavy equipment along the virtual guidance lines shown on the screen.

AR also offers the advantage of real-time information sharing. If multiple people view the AR display on site, the site manager and the operator can share the same image. Sending photos or videos of the AR view to off-site headquarters staff or design personnel enables understanding and instruction without on-site visits. Thus, AR visualization is not only easier to see but also a powerful communication tool on site.

Benefits of AR Displaying Drawings, Boundaries, and Buried Utilities

Using AR to visualize drawing information, boundary lines, and buried utility locations provides many benefits, including:

• Improved work efficiency: The repeated task of comparing paper drawings with actual conditions on site is reduced, and necessary information can be obtained simply by pointing a device. By replacing some tasks such as setting reference stakes and confirming survey points with AR, the time required for surveying and confirmation can be dramatically reduced. As a result, preparation work becomes more efficient, contributing to shorter construction schedules.

• Increased safety and reliability: AR can accurately indicate hazardous areas and important buried utilities, reducing the risk of accidental damage by heavy equipment. Since all workers can pay attention to the same locations, situations where someone “dug without knowing” can be prevented. Also, measurement tasks at heights or in tight spaces can be confirmed via AR from a safe distance, eliminating the need for workers to assume dangerous postures.

• Smooth communication: Shared visual information through AR makes it easier for site staff and designers/supervisors to have a common image. Truly, “seeing is believing”; complex design intentions that are hard to convey on paper drawings become immediately understandable. This smooths meetings and instruction, reducing mistakes due to misunderstandings.

• Promotion of DX and contribution to skill transfer: Using familiar technologies like smartphones and AR enables advanced surveying and confirmation work without the need for highly experienced surveyors. In construction sites facing serious labor shortages, this tool contributes to labor and personnel savings. It aligns with site digitization (ICT construction and i-Construction) and, as an intuitive technology that young workers accept, aids in skill transfer. A reproducible method that does not rely on veterans’ intuition and experience could become the future standard.

In this way, AR visualization on site is a groundbreaking solution that positively affects quality, efficiency, and safety. Especially in excavation work, it is unquestionably a powerful tool for accident prevention.

High-Precision AR Display Realized with RTK-GNSS

That said, ensuring accuracy is crucial to put AR technology to practical use on site. GPS built into ordinary smartphones and tablets can commonly have position errors of a few meters. Displaying underground utility positions with that level of error would not be useful for safety checks if the virtual display is off by meters. Also, conventional AR apps align by recognizing planes in the camera view or placing artificial markers, but as users walk around the display can gradually drift. In wide outdoor sites with few reference points, it has been difficult to maintain the correct position of virtual models for long with normal GPS accuracy. For these reasons, AR has remained an approximate visualization tool and has been difficult to apply to surveying or layout tasks that require millimeter- or centimeter-level precision.

The trump card to solve this issue is combining RTK-GNSS positioning with AR display. RTK (real-time kinematic) GNSS positioning dramatically improves positioning accuracy by using correction information from a reference station. Attaching a dedicated high-precision GNSS receiver to a smartphone or tablet and receiving correction information distributed over the network or centimeter-class augmentation services provided by Japan’s quasi-zenith satellite “Michibiki” (CLAS) enables a smartphone to determine its position with an error of about 1–2 cm (0.4-0.8 in). This is orders of magnitude better than the former meter-level accuracy and can be achieved with palm-sized devices.

If a smartphone can obtain accurate coordinates in the World Geodetic System, it becomes possible to directly link the pipeline routes shown on design drawings or GIS data with the real world. In other words, digital coordinates and physical site coordinates can be handled with a common reference. By linking coordinates included in the design data with the device position and orientation determined by RTK-GNSS on site, virtual objects (for example, buried pipe models or design lines) can be displayed precisely over the correct real-world positions.

With AR using high-precision GNSS, once alignment is set, the virtual model remains fixed at the correct location even if the user moves. Without complex initial calibration or marker placement, users can simply point the device to view AR models that automatically appear in the correct positions. This “no coordinate-alignment required” AR experience provides the sensation that points and lines on the design drawing are directly manifesting on site. For example, even at night or during severe weather, trusting the line displayed on the device gives confidence to excavate to the correct position. It is this centimeter-level accuracy (half-inch accuracy) in AR display that makes it a reliable tool to fundamentally reduce the risk of damaging buried utilities.

AR Use at Excavation Sites: Visualizing Boundaries and Buried Utilities

Now let’s look at specific ways AR can be used at excavation sites. The key is clearly indicating “where to dig” and “where to be careful.”

First is using AR for boundary line marking of excavation areas. In open-cut works, the excavation area shape and depth are defined in design drawings. Typically, this range is surveyed and marked on the ground with paint or stakes, but AR can greatly reduce that effort. If you prepare the 2D line data of the design in advance, simply pointing a smartphone on site will virtually display the planned excavation boundary lines on the ground. Operators can then operate heavy equipment while checking the lines on the screen and accurately excavate within the prescribed range without physical stakes. For example, if a red line indicates “do not excavate beyond this boundary,” the limit is immediately clear and surrounding workers can share the same information. Even inexperienced workers can work without hesitation by following visual guideline lines.

Next is visualization of buried utilities. If route information of underground utilities obtained in advance (GIS data or CAD drawings) is loaded into an AR app, pointing the camera on site will project the paths of underground pipes and cables onto the surface. For example, if a buried gas pipe crosses diagonally beneath your feet, a yellow virtual line or warning marker can be displayed along the ground directly above it. Workers can intuitively understand “there’s a gas pipe under here” and switch to hand-digging with a shovel near that area or use shallow bucket teeth on the machine to carefully remove the soil. This dramatically reduces the risk of striking a pipe.

Until now, fieldwork often involved measuring straight-line distances from drawings, marking the ground, and excavating cautiously around an assumed buried location. But with AR the route of buried utilities appears as it runs, enabling workers to grasp distances such as “there is a pipe within 1 m (3.3 ft) from here” concretely. This provides great reassurance to workers. If an unexpected utility not shown on the drawings is exposed, the positional relationship with displayed known utilities helps quickly judge—e.g., “this pipe is not on the new drawings, so it might be old.” Thus, AR not only presents existing information but also encourages on-site discovery.

By simultaneously showing excavation boundaries and buried utility locations with AR, it becomes clear “how far to dig” and “what to avoid.” Construction managers can identify hazardous points in advance and optimize work plans by checking them in AR, and morning briefings or hazard prediction activities can use actual footage to raise awareness. As a result, the entire site can share awareness and concrete measures toward “zero accidents.”

Easy High-Precision AR Introduction with Simple Surveying Using LRTK

As described, high-precision alignment is key to realizing AR visualization of buried utilities on site. How can such high-precision location information be easily obtained on site? Conventional methods required setting up surveying instruments and establishing control points through specialized procedures, but now it is an era in which centimeter-accuracy positioning is possible with just a smartphone. A representative example is our handheld GNSS system “LRTK.”

LRTK consists of a compact high-precision GNSS receiver that can be attached to a smartphone or tablet and a dedicated app. Turning on the power and launching the app starts RTK positioning. The device is lightweight and pocket-sized, eliminating the need to carry heavy tripods or stationary surveying equipment. No complex initial setup is required: tapping a button at the desired survey point records the latitude, longitude, and height of that instant. It is designed to be intuitive so that even those without specialized knowledge can operate it, making it accessible to both veterans and younger staff.

Yet positioning accuracy is surprisingly high; by receiving RTK correction information, you can stably obtain accuracy within a few centimeters (within a few inches). There is no need to purchase expensive large dedicated equipment or install a local base station, keeping initial costs lower than traditional high-precision surveying gear. Additionally, the LRTK receiver supports multiple satellite positioning systems (GPS, GLONASS, Galileo, etc.) as well as Japan’s satellites, allowing stable positioning even in areas with poor reception such as mountainous regions. Models that support Michibiki’s CLAS signal can obtain correction information directly from satellites even where cellular signals are unavailable, enabling continued high-precision positioning in tunnels or remote mountains. This consistency of accuracy across various sites is a significant reassurance for site personnel.

By using LRTK, anyone can easily obtain centimeter-accuracy positioning (half-inch accuracy), enabling smooth introduction of high-precision AR-based visualization of buried utilities. For example, measuring known site control points or building corners with LRTK and aligning them with the coordinate system of design drawings allows you to accurately overlay design data on the smartphone screen. Positioning tasks that once took a skilled worker half a day can now be reproduced by anyone in a short time with LRTK and AR. Consequently, AR displays for preventing buried utility accidents can be more readily incorporated into everyday site practice. LRTK requires no costly dedicated equipment and lets you measure whenever needed—truly a revolution in simple surveying. Actively leveraging these tools to raise site safety standards is a shortcut to zero excavation accidents.

Finally, the fusion of AR visualization and high-precision positioning technology is becoming the standard for future construction sites. To protect lives and social infrastructure, we should actively use these technologies and move forward toward the goal of “zero buried utility damage.”

FAQ

Q. Can AR really make underground buried utilities “visible”? A. AR is not magic that sees through the ground, but by overlaying prepared buried utility location data on real-world imagery, it enables an experience that feels as if the underground is visible. For example, if route information for a gas pipe recorded on drawings is imported into an AR app, viewing the ground through a smartphone on site will display a line showing that gas pipe’s path. You do not literally see the pipe itself in the soil, but you can visually confirm “what is buried here,” enabling judgments comparable to looking with the naked eye.

Q. What preparations or equipment are needed to display buried utilities in AR? A. Basically, an AR-capable smartphone or tablet and digital data of the buried utilities or design drawings are enough to get started. First, prepare position information for the pipes, cables, and boundary lines you want to display in GIS data or CAD drawing formats and load them into a compatible AR app. Next, since the smartphone must accurately know its current position and orientation, it is recommended to use a high-precision GNSS receiver (for example, a device like LRTK) in addition to the built-in GPS. AR itself will operate without high-precision GNSS, but display positions tend to have larger errors, making it less reliable for safety-critical use. With a smartphone using high-precision GNSS, prepared data can be accurately overlaid at the intended locations on site, allowing you to confidently use AR displays.

Q. Is it okay to rely only on a phone’s GPS and electronic compass for alignment? A. For precise alignment, the accuracy of a typical smartphone’s built-in GPS and compass is honestly insufficient. GPS errors of several meters are common, and compasses are easily affected by the local magnetic environment, making them unsuitable for indicating precise locations of underground pipes. Therefore, for full-scale AR utilization on site, it is realistic to use a high-precision GNSS unit that attaches to the phone. RTK positioning from high-precision GNSS enables determining current position within a few centimeters and also corrects orientation accurately based on GNSS. Using such auxiliary devices keeps virtual models on the screen consistently aligned with actual positions, making AR reliable for on-site decision making.

Q. If the drawing data is inaccurate, will AR display be affected? A. Yes. AR only displays the data provided, so if the original drawings are incorrect, AR will reproduce the same errors. For example, if a pipe is missing from the drawing, it will not appear in AR. This necessitates caution. However, introducing AR increases opportunities to notice deficiencies in existing data. If an AR check on site raises suspicion—for instance, “a pipe that should be straight on the drawing appears to deviate in reality”—you can re-examine the area with detection equipment. In short, AR is not omnipotent but is an effective complementary tool that prompts human awareness. AR is most effective with accurate data, and if data is imperfect it helps detect issues early on site. In any case, preparing data that reflects up-to-date drawings and prior survey results is a prerequisite for AR utilization.

Q. I’m worried that site workers won’t be able to use it well. Is special training required? A. AR app operation is very simple and intuitive. Basically, information is displayed automatically just by pointing a smartphone or tablet camera. People who are accustomed to smartphone cameras or map apps will have little difficulty. With a few hours of explanation or a simple demo at introduction, most workers can use it on site from the next day. In fact, younger workers find AR easier to understand than reading paper drawings. LRTK-type positioning devices are also simple: turn on the power and connect to the phone, so they are designed to be usable without expert knowledge. In practice, supervisors often lead by example, and workers naturally become interested and try it themselves, resulting in gradual and smooth adoption.

Q. Is the cost of introducing AR and high-precision equipment really justified? A. Preventing even a single buried utility damage incident has immeasurable value. Considering the costs of accident response and repairs, losses from construction delays, and reputational damage, investing in achieving zero accidents through AR introduction is very meaningful. Fortunately, recent high-precision GNSS devices and AR apps have become more accessible, and initial investment is relatively modest compared to buying dedicated machinery. Including labor savings from improved efficiency and reduced mistakes, the overall cost performance is high. Once data is prepared, it becomes an asset that can be reused at other sites and in future projects. AR utilization yields benefits in both safety and productivity and is becoming a next-generation standard practice. Early adoption will likely enhance future competitiveness. AR technology that transforms safety culture while improving efficiency is sure to deliver value beyond its cost.