Visualizing Underground Buried Pipes with AR: Achieving Zero Wrong Excavations for Safe, Secure Construction

Beneath cities, various lifelines such as water and sewer pipes, gas pipes, power lines, and communication cables are woven like a network. However, these buried underground pipes are literally hidden beneath the ground and thus often pose challenges during maintenance and construction. If buried utilities are accidentally damaged by heavy machinery, it can lead to serious incidents such as water leakage, gas leaks, or power outages. In fact, according to a survey by the Ministry of Land, Infrastructure, Transport and Tourism, more than 100 incidents of buried pipe damage occur each year, many of which are caused by wrong excavations by backhoes and the like due to insufficient pre-checks. Such incidents not only have a large impact on social infrastructure but also lead to construction delays and increased restoration costs. How can we "visualize" pipes that are invisible underground? — To solve this fundamental problem and realize safe, secure construction with zero wrong excavations, a promising new technology gaining attention in recent years is the visualization of buried pipes using AR (Augmented Reality).

Why prior knowledge of buried pipes is indispensable

To prevent accidents involving buried pipes, thorough pre-checks have long been conducted at construction sites. Before and after burial work, the positions and depths of pipes are recorded by surveying and kept in as-built drawings and photo ledgers. During on-site work, those drawings are referenced and pipe routes are sometimes spray-marked on the road surface, with excavation proceeding cautiously while relying on the experienced workers’ intuition to estimate the locations of buried utilities. As needed, ground-penetrating radar (GPR) is used to investigate pipe locations, and trial excavations may be performed for direct confirmation. While these conventional methods have ensured a certain level of safety, limitations of relying on paper drawings and fragmented records have been pointed out. In urban areas, repeated renovations have resulted in many cases where the information on drawings does not match the actual field conditions. Many engineers have had close calls when an unexpected pipe appeared at a depth that they thought should have been clear due to insufficient historical records. In short, it is not easy to fully grasp in one’s head the intersecting underground lifelines, and the fundamental challenge of infrastructure management is how to make the invisible visible.

What “visualizing underground” with AR means

AR (Augmented Reality) visualization of buried pipes is therefore being期待されている. AR is a technology that overlays digital information such as CG onto real-world images seen through a camera, and by using a smartphone or tablet one can virtually display the piping buried underground on the spot in a visible form. For example, if you point a smartphone camera at a road on site, the screen can render underground gas pipes, water pipes, and the like as if you were seeing through the ground surface. Workers can intuitively grasp “what kind of pipes run directly beneath their feet and at what depth,” allowing them to verify the underground structure as if visually inspecting the actual object without relying on drawings or guesswork. Because it is easy to understand on site even for non-experts, young or newly assigned technicians can also work safely.

However, to render buried utilities through AR, precise alignment with the real-world space is indispensable. If one simply relies on a smartphone’s GPS or electronic compass, positional errors of several meters can occur, causing the displayed virtual pipe models to be significantly offset from the actual buried locations. This not only prevents seeing through the ground but can lead to misidentification and increased danger. Conventional AR systems often require placing alignment markers at each site or performing initial calibration to manually adjust model positions. For wide-area roadworks or buried pipe management, it is unrealistic to place markers or manually adjust settings at every location. Overcoming the challenges of “accuracy” and “effort” is therefore the key to making AR for buried pipes practical.

High-precision AR achieved with RTK-GNSS and smartphone LiDAR

A solution to these challenges is the markerless high-precision AR enabled by the combination of smartphone + LiDAR + RTK-GNSS. Recent smartphones come equipped with advanced AR platforms (ARKit and ARCore) that capture device motion from camera images and IMU (inertial measurement unit) data to understand the surrounding environment in real time. Higher-end smartphones also include compact LiDAR (light detection and ranging) sensors that can instantly acquire the surrounding terrain and structures as three-dimensional point cloud data. Because LiDAR can scan the ground and structures with high accuracy, virtual objects (such as 3D models of buried pipes) can be stably overlaid onto the real world, and occlusion—where virtual objects are hidden behind real ones—can be rendered naturally. In other words, smartphones are now capable of camera imagery + self-positioning + surrounding 3D map construction automatically.

The final piece is for the device to accurately know “where it is located.” This is where high-precision positioning technology RTK-GNSS (Real-Time Kinematic satellite positioning) shines. As mentioned, normal GPS can have several meters of error, but by using correction information from a base station in RTK mode, errors can be reduced to a few centimeters. RTK has long been used in surveying, and recent miniaturization and cost-reduction of receivers have produced RTK-compatible ultra-compact GNSS receivers that can be attached to smartphones. By combining such high-precision GNSS devices with a smartphone, the device’s position can be captured in a public coordinate system with centimeter-level precision, thus minimizing the offset between the virtual model and the real-world space. This markerless capability allows AR displays to remain stable even when walking freely on site, turning previously black-box underground infrastructure into visible on-site information.

Moreover, an era in which anyone can carry high-precision positioning tools in their pocket is near. Without lugging heavy surveying equipment, each technician can attach an RTK-GNSS receiver to their own smartphone, carry it around, and quickly use it for surveying or AR visualization when needed. In fact, modern systems display current coordinates and navigation information on the smartphone screen with an intuitive Japanese UI so that users without specialized knowledge can operate them. For example, layout work that used to require two people for staking can now be done by one person using a smartphone set on an RTK-equipped pole, following on-screen guidance to achieve accurate positioning. Allowing anyone to easily use high-precision GNSS positioning dramatically improves productivity and accuracy in surveying and construction management.

When the text refers to centimeter-level accuracy, it will be presented as cm level accuracy (half-inch accuracy).

DX of buried pipe management using 3D scan records and the cloud

The combination of centimeter-class positioning and smartphone AR enables end-to-end digitalization (DX) from construction records to maintenance of buried pipes. Here is the workflow of 3D scanning records and AR visualization for buried pipes.

• 3D recording of buried pipes (during construction): In works where new piping is buried under roads, the pipes and the surrounding excavation area are scanned with a smartphone (equipped with LiDAR) before backfilling. If an RTK-GNSS receiver attached to the smartphone is used, the acquired point cloud data is automatically tagged with high-precision world coordinates and uploaded to the cloud. The system automatically generates 3D mesh models of the piping from the point cloud, creating a digital record of the exact route, depth, and shape of the buried pipes. Traditionally, measurements and drawing creation or spray-marking of pipe routes on temporarily restored surfaces were required after burial, but with this method, a detailed 3D buried record is completed simply by scanning.

• Data sharing and ledger management: The acquired point cloud and model data of buried pipes can be immediately shared via the cloud and accessed from office PCs or other devices. Importing them into an online ledger or GIS and storing them as infrastructure asset information helps in planning future inspections and coordinating with other works. Cloud-based analysis of point cloud data enables one-click execution of advanced digital processing such as measuring pipe diameters and burial depths on arbitrarily selected sections or automatically calculating excavation and backfill volumes. Site supervisors and construction managers can thus obtain necessary numerical information instantly without having to create CAD drawings or perform manual calculations. Real-time sharing between site and office also allows office staff to issue instructions while viewing the point cloud model without visiting the field, and to expedite arrangements such as spoil disposal and equipment procurement.

• On-site utilization through AR visualization (during maintenance): The 3D data of buried pipes accumulated in the cloud can be displayed with AR on-site for future inspections or renovation works. For example, if the same road needs to be excavated years later for another project, the old paper drawings and trial excavations would have been required to estimate and confirm pipe locations. But with previously acquired 3D buried records, simply starting an AR app on a smartphone and pointing the camera on site will visually display the locations and paths of pipes buried beneath the road surface. Information such as “a single water pipe with a diameter of ○○ mm (○○ in) runs directly beneath here” or “a gas pipe runs in parallel further in” can be shown as colored virtual pipe models overlaid on the real scene. Depth information can also be displayed with labels, making vertical relationships clear at a glance—for example, “this water pipe is buried 1.2 m (3.9 ft) below the ground surface.” The task of locating buried utilities, which used to rely on the intuition of experienced veterans and past records, becomes a visible operation based on digital data that anyone can perform.

Through this workflow, the cycle of buried pipe management—from surveying and recording to data sharing and on-site AR verification—is digitally integrated. The detailed 3D information that could not be reproduced with paper drawings or photo ledgers can be preserved so that information does not degrade over time and is always managed with high-precision spatial coordinates. As a result, the accuracy of buried infrastructure maintenance and management is improved, contributing to future accident prevention and more efficient planning.

Effects and benefits brought by AR visualization of buried pipes

By leveraging the above RTK × AR technology, various benefits arise for infrastructure inspection and civil engineering sites. The main effects are summarized below.

• Prevention of accidents involving underground utilities: AR lets you accurately grasp buried locations and depths before excavation, greatly reducing the risk of pipe damage due to wrong excavations by heavy machinery. Visualizing unseen hazardous areas such as gas pipes and power cables in advance significantly strengthens safety measures.

• Improved efficiency and labor savings: The time-consuming task of comparing drawings and the field to estimate positions is eliminated, enabling precise excavation and investigation only where needed, which shortens work time. Multiple processes such as surveying, staking, and pipe recording can be completed with a single smartphone, enabling reductions in personnel, shortened construction schedules, and cost savings.

• Improved recording accuracy: Digital records using point cloud scans can store the position and shape of buried utilities accurately down to the millimeter. This provides far more reliable data than paper drawings or oral transmission, forming a trustworthy information base for future maintenance ledgers. Because data is stored in the cloud, there is no worry about loss or degradation.

• Advanced maintenance and inspection planning: AR displays innovate replacement planning and routine inspections of aging pipes. By overlaying current 3D data with past repair histories on site, sections requiring replacement can be quickly and accurately identified and reinforcement measures considered. For instance, in investigations of road collapse risk, AR can display hollow locations identified by GPR and sewer pipe deterioration data while marking the site, ensuring risk spots are not overlooked. Such data-driven preventive maintenance dramatically improves efficiency in addressing infrastructure aging.

• Smoother information sharing and consensus building: AR visualizations function as a common language on site. In roadworks where multiple buried utility operators (water, gas, communications, etc.) are involved, integrating each operator’s pipe data and displaying it in AR enables a joint on-site meeting where everyone shares the same “visualized underground” information. This reduces the effort of reconciling paper maps and prevents misunderstandings or miscommunications that lead to trouble. When explaining to clients or nearby residents, pointing a smartphone to intuitively show “this is how many pipes run under this road” makes it easier to gain understanding and smoothly build consensus.

• Improved quality of pre-construction planning: Overlaying 3D design data such as BIM/CIM onto the site via AR greatly aids pre-construction planning and stakeholder consensus. Because the completed image and underground structures that are hard to convey on drawings can be confirmed three-dimensionally on site, sharing construction process images and checking for clashes with other buried utilities becomes easier. This visual clarity improves the quality of pre-construction consultations and explanations for clients and local residents, facilitating overall project smoothness.

• Promotion of on-site DX: Introducing RTK × AR strongly promotes digital transformation (DX) at construction sites. This aligns with the Ministry of Land, Infrastructure, Transport and Tourism’s *i-Construction* initiative (measures to improve productivity in construction through ICT) and contributes to advanced safety and construction management using three-dimensional data and ICT. Work that once relied on experience and intuition shifts to a data-driven approach, and visualization enables everyone to make accurate decisions and perform tasks on site. As a result, rework and construction errors are reduced, contributing to lower life-cycle costs.

Field use cases and future prospects

This AR visualization technology for buried pipes is already being applied in the field. In Japan, a startup has developed a system that combines an RTK positioning unit with a tablet to display underground buried pipes in AR on-site. Without spreading out drawings or performing trial excavations, users can grasp buried utilities in three dimensions on the spot, contributing to improved safety and work efficiency. Trials at actual construction sites reported significant effects: records of buried pipe work were completed without photo shoots or CAD drawings, and subsequent excavation work could immediately locate pipes using AR displays. Workers praised the system, saying “locating buried utilities that used to rely on intuition can now be done by anyone,” and “the operation was intuitive and required no special training,” indicating strong on-site adoption potential.

Looking overseas, outdoor high-precision AR systems are attracting attention as a new disruptive technology in the construction industry. Systems that combine high-performance GNSS receivers and AR allow 3D design models to be overlaid on the real scene through a smartphone, enabling intuitive on-site sharing and verification of complex BIM models and underground utility information. In both Japan and abroad, initiatives for construction DX and smart maintenance using RTK × AR are accelerating, with introductions in a wide range of projects from bridge construction to water and sewer maintenance. It is highly likely that such high-precision AR technologies will become more generalized and simplified, becoming the new norm across the industry. A future in which each worker routinely points a smartphone on site to check design drawings and the status of buried utilities in AR while working is fast approaching.

Conclusion: Simple surveying, AR display, and data sharing starting with LRTK

AR visualization of buried pipes is transforming infrastructure maintenance and civil engineering. By overlaying digital data onto the real world with centimeter-level precision, tasks that once relied on veteran experience are shifting toward data-driven smart construction. One notable solution that makes this cutting-edge technology easy to use on site is LRTK.

LRTK is an integrated system that enables anyone to easily achieve centimeter-level positioning and AR visualization by using a compact RTK-GNSS receiver attached to a smartphone and a dedicated app. While many general AR tools require pre-placed markers or complex initial calibration, LRTK can achieve RTK Fix (establish high-precision positioning) within tens of seconds after powering on, allowing immediate start of high-precision AR. No special calibration work is required—simply power on and start on site. LRTK also integrates with the cloud, enabling seamless operations such as downloading design drawings and point cloud survey data for AR display on the spot, or instantly uploading and sharing data acquired on site. Designed for intuitive use by non-experts, there are field reports that one smartphone per person completed surveying, staking, pipe recording, and AR simulation.

By leveraging LRTK, sites can dramatically improve productivity and safety without expensive equipment or large specialized teams. Beyond visualizing buried pipes, it can be applied to verifying as-built shapes of structures, construction navigation, and a wide range of uses—truly a “universal surveying instrument” and a trump card for on-site DX. Surveying firms, municipal civil engineering departments, and construction contractors should consider adopting this cutting-edge technology into their operations. For more details on product information and case studies, please visit the [LRTK official site](https://www.lrtk.lefixea.com/). With LRTK, evolve your site to the next stage and realize safe, secure infrastructure construction and maintenance.