Table of Contents

• Introduction

• What Is AR Visualization of Underground Utilities?

• Effects of AR on Preventing Construction Errors

• Improved Inspection Accuracy through AR

• AR-Promoted Smooth Consensus Building

• Challenges and Prospects for AR Adoption

• Summary

• Simple Surveying with LRTK

• FAQ

Introduction

On construction sites, it is always necessary to be aware of infrastructure embedded underground, such as water and sewer pipes and power cables, which are normally invisible. If the locations of these underground utilities are not accurately understood, excavation can accidentally damage pipes or structures can be placed in the wrong positions, leading to construction errors. Traditionally, these issues were addressed by checking drawings in advance or marking the ground, but human error cannot be completely eliminated that way. A new approach attracting attention to solve these problems is AR (augmented reality) visualization of underground utilities. If tablets or smartphones can display underground pipes as if seen through the ground, this could help prevent construction mistakes. This article answers that question by explaining in detail the effects of AR visualization of underground utilities from the perspectives of "preventing construction errors," "improving inspection accuracy," and "promoting consensus building."

What Is AR Visualization of Underground Utilities?

So what exactly is AR visualization of underground utilities? Simply put, it digitizes the location information of buried pipes, cables, and the like, and overlays that data onto the real-world scenery. On site, tablets or smartphones with dedicated AR apps installed are used. When the camera is pointed at the ground, the screen displays the actual scene together with CG or lines representing the pipes or structures expected to be underground, making it appear as if you can see through the ground.

With this mechanism, workers can intuitively "see" and confirm normally invisible buried utilities. Without relying on paper drawings or spray markings on the surface, the spatial relationships of underground infrastructure can be understood through the device’s screen, dramatically improving on-site safety and efficiency. For example, instead of memorizing from a drawing that "a gas pipe runs around here," if the gas pipe’s route is drawn in real time on the actual ground, it becomes obvious to everyone.

Accurate AR display requires highly precise measurement of the device’s position and orientation. Ordinary GPS can have errors on the order of several meters (several feet), making it insufficient for construction site use. Therefore, technologies that use high-precision positioning called RTK-GNSS (real-time kinematic) or correction information from electronic reference stations to reduce errors to within a few centimeters (within a few inches) are employed. Also, in environments where GNSS cannot be used, such as indoors or in dense high-rise areas, other alignment methods are used, such as SLAM (simultaneous localization and mapping) using camera images or placing QR markers for correction. By combining these advanced positioning technologies with 3D data, AR display of underground utilities on construction sites is becoming a reality.

Effects of AR on Preventing Construction Errors

How exactly does AR visualization of underground utilities help prevent construction errors? The primary effect is a reduction in the risk of incorrect excavation or pipe damage. Traditionally, to grasp the location of underground utilities on site, methods such as measuring distances on drawings and marking the ground were used. However, if markings shift or fade, re-measurement is necessary, and during actual heavy equipment operation operators may rely on feel for depth or position, which can result in contact with buried pipes.

By using AR visualization, workers can visually identify hazardous underground locations in advance, greatly reducing such human errors. For example, if a tablet displays the routes of underground gas or water pipes, workers can immediately see which areas to avoid before digging. The incidence of accidents like "accidentally cutting an existing pipe" should decrease. For heavy equipment operators, following AR-displayed guide lines provides reassurance that digging along those lines is safe, reducing unnecessary slowdowns from over-caution.

Additionally, the ability to detect positional deviations of installed elements on the spot is important. AR can overlay not only existing features but also design models of structures to be installed. For example, when placing a foundation underground, projecting the finished model onto the site during work allows real-time confirmation of whether the installation is shifting from the planned position. Even a slight deviation will be visualized on AR as a discrepancy between the real object and the model, allowing immediate detection without later cross-checking with drawings. In this way, discovering positional and dimensional errors that commonly occur during construction on the spot prevents rework. As a result, construction quality improves, rework is reduced, and this contributes to shorter schedules and cost savings.

Improved Inspection Accuracy through AR

AR visualization technology improves not only error prevention during construction but also the accuracy of post-construction inspections and maintenance. When confirming the as-built condition of structures or the health of infrastructure, traditional methods often rely on drawings and measuring instruments to check on-site conditions, using visual inspection and experience to identify problems. With AR, because data can be overlaid on the real scene for comparison, even minor defects are less likely to be missed.

For example, in routine inspections of bridges and tunnels, overlaying past health survey data and repair histories with AR on the current condition allows pinpointing of deterioration locations. If a crack was previously recorded, displaying an AR marker at that location enables inspectors to find it precisely in the field and compare it with prior data to see if it has worsened. In building and structural inspections, AR lets you visually confirm discrepancies between design drawings and post-construction conditions. If the position of a column or wall differs even slightly from the design model, it will be shown on the screen as a deviation, so millimeter-level discrepancies (millimeter-level discrepancies (~0.04 in)) that conventional measurements might miss can be noticed.

With improved inspection accuracy, necessary repair locations can be accurately identified, avoiding excessive work or unnecessary touch-ups and thereby reducing costs. For instance, for underground pipe maintenance that once required extensive excavation to check, AR that provides precise buried locations can limit inspection to a restricted area. Inspectors no longer need to carry paper drawings and repeatedly check their current location; they can efficiently inspect on site by simply pointing a device. With AR, inspection work becomes data-driven and smart, enabling safe and reliable inspections with minimal misses.

AR-Promoted Smooth Consensus Building

Introducing AR technology, including visualization of underground utilities, also greatly impacts consensus building among site stakeholders. Construction involves communication with many stakeholders, including contractors, clients and supervisory authorities, and even local residents. Traditionally, communication relied heavily on design drawings, renderings, and verbal explanations. However, drawings or text alone often fail to fully convey the site image, and misunderstandings such as "this is not what I expected" or "the explanation is hard to follow" can impede consensus building.

Using AR, completion images or utility conditions can be directly displayed over the real scene, allowing all stakeholders to share the same visual information. For example, when explaining to a client before construction, displaying a 3D model of the planned structure over the actual site on a tablet enables the client to see the future completed form with their own eyes. The sense of scale and relationships to surroundings, which can be hard to convey with words or drawings alone, become obvious and help prevent misunderstandings like "this is not what I thought." As a result, the time required to reach consensus can be significantly shortened.

Consider a case where a design change becomes necessary during construction. Normally, explaining changes on drawings and gaining client understanding can take time. However, if you project a 3D model of the proposed change on site using AR, the client can intuitively grasp the post-completion appearance, making it easier for them to accept the changes. This visual sharing before decisions reduces losses such as "explanations taking too long so construction cannot proceed until agreement is reached."

AR is also powerful during on-site inspection attendance. For example, in roadworks near existing underground utilities, if managers can see in advance via AR that protection measures for buried utilities are in place, utility owners can feel confident entrusting work. In an actual Ministry of Land, Infrastructure, Transport and Tourism project, using a GNSS-compatible AR system to confirm the separation between buried pipes and the construction area in real time not only eliminated the need for traditional ground markings but also made joint inspections with utility managers smoother because "we could explain things while looking at the screen." This example shows how AR visualization of the site contributed to building trust with clients and related organizations.

Thus, AR technology smooths the consensus-building process itself. By sharing AR screens and acquired data via the cloud, remote stakeholders can grasp site conditions in a timely manner without visiting. In the future, visualization through AR combined with high-precision positioning may become the standard for consensus building. From clients to site workers, everyone would view the same AR imagery during meetings and make instantaneous decisions—such a future for construction sites is becoming more plausible.

Challenges and Prospects for AR Adoption

Although AR visualization offers many benefits, several challenges are noted for full-scale on-site adoption. The foremost is the need to prepare high-accuracy data and a precise positioning environment. If the underground utility information displayed by AR is based on old drawings or inaccurate records, the visualization will be mislocated and potentially dangerous. Therefore, accurately surveying the locations of buried utilities and creating 3D models in advance is indispensable. As mentioned, if the device cannot determine its own position to centimeter-level accuracy (half-inch accuracy), the gap between reality and virtual space will be too large for practical use. High-precision GNSS positioning requires specialized knowledge and equipment, and this is a high hurdle for ordinary sites.

Next, the skill level and acceptance of site staff are challenges. In sites lacking personnel familiar with handling 3D data such as BIM/CIM or operating the latest equipment, newly introduced AR systems may not be used effectively. Especially during initial implementation, device preparation, calibration, and data preparation can be time-consuming, and some may avoid the system thinking "the traditional method is faster." Therefore, it is important that systems be user-friendly so anyone on site can use them intuitively and that sufficient training be provided before introduction.

Recently, technological advances have begun to offer solutions to these challenges. For high-precision positioning, accessible RTK-GNSS devices that are easy to use—described later—have appeared, making centimeter-class positioning (half-inch accuracy) possible even without specialist technicians. By creating systems that share the latest data on the cloud, omissions in updating drawings can be prevented. Combined with the Ministry of Land, Infrastructure, Transport and Tourism’s i-Construction movement, the groundwork for incorporating digital technologies on site is being built. With more pilot projects and adoption cases, AR-driven construction DX (digital transformation) is steadily progressing.

Looking ahead, standardization and generalization of AR are expected. What was once limited to large-scale projects or advanced firms is likely to become a common tool even on small to medium-sized sites. Reports from trial implementations already indicate improvements such as "increased safety and productivity" and "reduced rework," and evaluations on site are positive. If the industry-wide momentum to accept AR grows, it could substantially reduce construction errors and contribute to labor-style reforms.

Summary

As discussed, AR visualization of underground utilities offers a wide range of benefits—from preventing construction errors to improving inspection accuracy and smoothing stakeholder consensus building. Making the invisible visible reduces safety risks and operational waste in advance and facilitates on-site communication—this technology has the potential to change conventional wisdom on construction sites. Of course, AR requires preparatory work such as high-precision data and equipment, but technological innovation is lowering those barriers. Recently, solutions have emerged that allow anyone to perform centimeter-level accuracy (half-inch accuracy) positioning and AR display using a smartphone, making site adoption easier.

In conclusion, AR visualization of underground utilities can be a powerful means of preventing construction errors. Beyond error prevention, it also brings quality improvements at the inspection and maintenance level and enhances smooth communication with stakeholders such as clients. This technology, which fuses digital data and on-site work, can be considered one of the pillars of DX promotion in the construction industry. In the near future, it may become commonplace to see workers holding up tablets to check underground utilities and projected completion models while working.

Simple Surveying with LRTK

Finally, as a new tool to easily realize AR visualization on site, we introduce LRTK. LRTK is a solution that combines a compact high-precision GNSS receiver with a smartphone to enable simple high-precision positioning on site. By using a dedicated ultra-compact RTK-GNSS device (for example, an "LRTK Phone" that can be attached to the back of a smartphone), an ordinary smartphone instantly becomes a surveying instrument and AR terminal with centimeter-level accuracy (half-inch accuracy). Without complicated base station setup or marker placement, simply turning on the device automatically acquires high-precision self-positioning and projects 3D design data accurately into the real space.

With this simple surveying system, intuitive use of AR technology is possible even for those who are not surveying specialists. For example, a single technician can walk the site with a smartphone and perform tasks on the spot from confirming the location of buried utilities to guiding pile-driving positions, checking as-built conditions, and taking photo records. Survey results and site photos can be shared to the cloud instantly, reducing the need to return to the office to produce drawings. High-precision AR realized by LRTK directly reduces construction errors and streamlines surveying work, contributing to overall productivity improvements on site. Furthermore, accurate as-built data acquired can be shared with clients in real time, greatly smoothing the consensus building mentioned earlier.

Thus, LRTK plays a role in significantly lowering the barriers to AR visualization adoption by enabling "high-precision AR anyone can use immediately." Even sites that hesitated because "the equipment seems expensive" or "operation seems difficult" can try AR easily using LRTK. Leverage the latest technology to achieve safe and efficient smart construction.

FAQ

Q: What is required to perform AR visualization of underground utilities on site? A: Fundamentally required are digital data containing accurate location information of buried utilities (for example, drawings or 3D models of buried pipes) and AR-capable devices to display them on site. First, survey the locations of the buried utilities and convert them into 3D data, then load them into an AR app on a tablet or smartphone. To accurately determine device position, use high-precision GPS (GNSS), RTK base stations, or, when necessary, correction information services via the internet. In short, AR visualization is possible only when you have both the data of "what is where underground" and the positioning technology to overlay that data on site without misalignment.

Q: Can AR really make underground utilities "visible"? A: Yes—the device screen displays them as if they were actually visible. AR overlays virtual images onto the real world; it does not literally see through the ground. However, if you have accurate positional and shape data of the utilities, rendering them aligned with the real scenery produces the visual effect of seeing through the ground. For example, if a water pipe is buried 1 m (3.3 ft) below the ground in front of you, an AR app will display the pipe’s CG model in the same location on the screen. As a result, the pipe appears to float under the ground when viewed through the device.

Q: Can AR be used indoors or where GNSS is not available? A: Methods exist to utilize AR where GNSS (GPS) does not reach, but it is not as straightforward as in outdoor environments and requires some ingenuity. For indoor or tunnel locations, SLAM techniques that estimate the device’s position using camera images or methods that align using markers placed on ceilings or walls are options. In fact, some major construction firms’ underground utility visualization systems combine proprietary SLAM functions to handle cases where GNSS signals are unavailable. However, accuracy tends to be lower than outdoors in such cases, so more careful operation is required. In GPS-unstable dense urban areas, measures such as using simple base stations set up nearby or matching known reference points are employed case by case.

Q: Do you need specialized skills to handle AR? A: Previously, advanced equipment operation and 3D software knowledge were required, but recent AR systems have become quite user-friendly. Basic operations are often intuitive—tapping a tablet screen or simply pointing the device—and field workers can learn them with short-term training. However, preparatory data work (such as converting drawings to 3D and aligning coordinates) requires some knowledge, so having an IT-savvy person support initial stages is desirable. Tools like LRTK simplify device setup, so even non-specialists can handle high-precision AR.

Q: What kinds of construction sites are suitable for AR visualization of buried utilities? A: AR is effective for any project involving underground utilities, but it is especially beneficial for urban roadworks, piping works, and infrastructure maintenance. On sites with many underground lifelines, AR’s ability to spatially visualize relationships is highly valuable for safety. It is also useful for trench excavation, foundation works for bridge piers, and other sites where positional relationships to underground structures are critical. Additionally, AR is powerful for cases where stakeholders want to confirm post-completion appearance or structure placement in advance, such as public projects requiring aesthetic consideration or resident briefings. In short, AR visualization of buried utilities demonstrates its true value where "sharing the invisible is necessary" or where "delicate work with no margin for error" is performed.