Environmentally Friendly AR Civil Engineering: Achieving Eco-friendly Construction by Reducing Unnecessary Excavation

Table of Contents

• What is AR civil engineering?

• Problems Caused by Unnecessary Excavation

• How AR Technology Reduces Unnecessary Excavation

• Why AR Civil Engineering Is Environmentally Friendly

• Other Benefits of AR Utilization

• Field Use Cases of AR Civil Engineering

• Key Points for Introducing AR Civil Engineering

• Towards AR Civil Engineering Accessible to Everyone: Future Prospects and the Use of Simple Surveying

• FAQ

What is AR civil engineering?

In recent years, the use of AR (augmented reality) technology in the construction and civil engineering industries has attracted attention. AR civil engineering refers to the practice of using AR technology at construction sites to overlay digital design information and 3D models onto real-world scenery. For example, when you point a smartphone or tablet, a life-size rendering of a structure not yet built or the location of buried underground pipes can be displayed over the actual view. This allows intuitive verification of planned drawings on site, greatly helping to prevent construction errors and improve work efficiency.

The advantage of AR civil engineering is that it allows spatial information that is difficult to grasp from paper drawings or 2D plans to be visually understood on site. Since the completed image and the placement of structures—previously left to imagination—can be confirmed in the field, it becomes easier for all stakeholders, such as clients, designers, and construction personnel, to deepen their understanding. This kind of visualization of the site through digital technology is spreading widely—from large companies to small and medium-sized contractors and even local governments—within the trends promoted by the Ministry of Land, Infrastructure, Transport and Tourism, such as *i-Construction* and construction DX (digital transformation).

Problems Caused by Unnecessary Excavation

In civil engineering, "unnecessary excavation" refers to unwanted digging that goes beyond the planned scope or digs in the wrong place. Why does this happen? In traditional construction, position setting on site relies on paper drawings, so human error and communication mistakes are likely to occur. Particularly when the locations of underground utilities are not accurately known, crews may excavate more broadly for safety or perform trial excavations to confirm conditions. As a result, soil is excavated beyond what is necessary, leading to inefficiencies such as having to backfill later.

Unnecessary excavation causes several problems. First, increased construction time and costs. Extra excavation and backfilling take time, delaying overall progress and increasing labor and heavy machinery fuel costs. Second, safety risks. If unnecessary areas are excavated, surrounding ground may become unstable, or existing buried pipes and structures may be damaged. This can affect not only construction workers but also the surrounding environment and nearby residents. Third, environmental impact. Unnecessary excavation generates excess spoil (excavated soil), creating environmental burdens from disposal and transport (increased fuel consumption of dump trucks and CO2 emissions). Also, additional materials may be needed for backfilling, leading to resource waste. In these ways, unnecessary excavation poses significant economic and environmental downsides.

How AR Technology Reduces Unnecessary Excavation

So how can AR technology be used to reduce unnecessary excavation? The key point is the ability to visualize accurate positions and extents on site. Below are some specific ways AR civil engineering reduces unnecessary excavation.

• Presentation of accurate excavation areas: Using AR, the areas to be excavated and approximate depths can be displayed as lines or surfaces in the real world. For example, virtual marking lines or excavation cross-section models can be projected onto the ground through a smartphone, allowing workers to instantly understand "where to dig from and to" and "how deep to dig." This prevents over-excavation caused by misreading drawings or measurement errors.

• Visualization of underground utilities: By displaying the positions of buried pipes and cables in AR, workers can visually confirm invisible obstacles before excavation. Traditionally, crews had to dig carefully based on drawings and experience, and if buried utilities were damaged, significant rework could occur. If AR reveals accurate locations of buried utilities in advance, workers can access the target without unnecessarily widening the excavation area, helping prevent hits on buried pipes.

• Pre-simulation of construction areas: AR civil engineering allows planned structures and earthworks extents to be simulated on site before construction begins. For instance, AR can visualize the areas for fill and cut on the ground, allowing confirmation of interplay with surrounding terrain and required soil volumes. This helps prevent situations in construction where more is excavated than expected or fill is insufficient. In other words, excavation volume can be optimized from the planning stage.

• Checking differences between as-built and design models: During construction, AR can overlay the current as-built shape (the actual shape after construction) and the design model for comparison. On a smartphone screen, comparing the virtual design model and the real structure or terrain makes it possible to instantly determine whether too much or too little has been excavated. For example, in roadwork, one can immediately see whether the subgrade excavation depth is appropriate by viewing a color-coded heatmap in AR. Early detection of discrepancies allows corrections before unnecessary excavation progresses, resulting in efficient construction without waste.

As shown above, using AR technology dramatically improves on-site visibility and information accuracy, preventing "over-excavation" and "excavation mistakes" beforehand. As a result, not only does overall construction efficiency improve, but it also leads to secondary reductions in environmental burden.

Why AR Civil Engineering Is Environmentally Friendly

Introducing AR civil engineering brings significant environmental benefits. As mentioned earlier, reducing unnecessary excavation enables eco-friendly construction both directly and indirectly. Here we summarize why AR civil engineering is environmentally friendly.

• CO2 reduction by reducing heavy machinery operation: Heavy machinery such as excavators and dump trucks used for excavation and backfilling consume a lot of fuel and emit CO2 during operation. By improving construction accuracy with AR and eliminating unnecessary work, heavy machinery operating time itself can be shortened. For example, if unnecessary excavation is avoided, there is no need to operate additional machinery later for backfilling. Shorter heavy machinery operation time = reduced greenhouse gas emissions, contributing to global warming countermeasures.

• Reduction of spoil and resource conservation: Excess excavation produces spoil that must be disposed of. Transporting and disposing of spoil requires fuel and processing energy, imposing environmental burdens. If AR civil engineering maintains appropriate excavation volumes, excess spoil will not be generated, leading to waste reduction. Also, over-excavation often necessitates additional soil or materials for backfilling, which can be avoided, contributing to resource conservation.

• Reduced environmental pollution risk by preventing accidents: If incorrect excavation damages water/sewer or gas pipes, it can lead to soil erosion from leaks or air pollution from gas leaks, causing environmental harm. Accurately identifying the locations of buried utilities with AR prevents such excavation mistakes, reducing the risk of environmental pollution. Lowering these risks contributes to protecting local ecosystems and maintaining safe living environments.

• Consideration for the surrounding environment (noise and vibration reduction): Reducing unnecessary excavation directly shortens construction periods and reduces the number of operating machines. As a result, noise and vibration around the site are also suppressed. Faster completion reduces nuisance to nearby residents, making AR civil engineering effective in terms of community environmental consideration.

For these reasons, the use of AR technology is not only a means to improve construction efficiency and accuracy, but can become a key solution for achieving sustainable construction. The ability to contribute at the site level to current demands such as the SDGs (Sustainable Development Goals) and carbon neutrality should not be overlooked. Waste-free construction realized by AR civil engineering is a step toward environmentally friendly, eco-conscious construction.

Other Benefits of AR Utilization

AR civil engineering brings various benefits to sites beyond environmental aspects. Here we touch on advantages that directly connect to site operations.

• Smoother communication: Since AR allows anyone to visually share the site situation and the completed image, it is easier for stakeholders with different positions—clients, contractors, residents—to develop a common understanding. For example, showing the post-completion landscape in AR in advance makes it easier to gain understanding at residents' briefings. In this way, AR helps speed up consensus building.

• Advanced and labor-saving construction management: Using AR features on smartphones or tablets, construction managers can inspect as-built conditions and check progress on the spot. Traditionally, measurements and photos had to be taken and compared with drawings in the office, but AR enables real-time on-site verification, greatly reducing labor. Also, AR tools are intuitive for younger staff, allowing a new management style that does not rely solely on experienced personnel.

• Improved safety: By using AR simulation functions, operators can preview excavator swing ranges and material delivery paths in a virtual space. Detecting hazardous spots and obstacles along work routes in advance helps prevent labor accidents. In addition, always working while viewing design information on site reduces "mistakes due to misinterpretation," contributing to improved safety and quality.

• Increased productivity and cost-effectiveness: Introducing AR civil engineering leads to shorter construction times and lower costs through the aforementioned efficiencies and error reductions. Reducing surveying and rework saves personnel and time, allowing resources to be allocated to other tasks. With fewer people accomplishing more work, AR can be a trump card for improving productivity in the construction industry suffering from severe labor shortages.

Thus, AR technology delivers positive effects across communication, quality, safety, and cost in addition to environmental benefits. It is truly a comprehensive solution for realizing a "smart and resilient site."

Field Use Cases of AR Civil Engineering

How is AR civil engineering actually used in the field? Here are some representative cases and scenes.

• Verification of buried utilities in underground infrastructure work: In buried works for water/sewer and gas lines, it is important to know the positions of pipes that will be invisible from the surface after completion. At one site, before backfilling a laid pipe, the surroundings were scanned with a smartphone LiDAR scanner to acquire 3D data of the pipe. If that data is uploaded to the cloud, the position and depth of the underground pipes can be visually confirmed via smartphone AR display from above the road even after backfilling. This allows later repair works to avoid pipes accurately without relying on experience or intuition, improving safety and efficiency.

• As-built inspection in bridge construction: For concrete structures like piers and abutments, as-built inspection to confirm that the post-cast shape matches the design is essential for quality control. Traditionally, points were measured and cross-sections compared, but with AR one can visually verify by overlaying the planned 3D model with the actual object. Since discrepancies can be checked on a smartphone immediately after construction, corrective work can begin at once if necessary. This minimizes rework and balances quality assurance with reduced backtracking.

• Cut and fill simulation in land development: On large development sites, it is important to accurately execute earthwork plans. In one project, a heavy equipment operator used a tablet mounted in the cab to display the designed final terrain model on the ground in AR. This allowed the operator to understand in real time how much to excavate or fill while driving. As a result, mistakes of excavating or filling too much were drastically reduced, preventing losses such as having to re-transport large amounts of soil later.

• Consensus building in road widening projects: When widening or improving roads, it is often necessary to explain the post-completion image to local residents. Traditionally, designers distributed perspective drawings on paper, but one municipality used AR at a local briefing. When officials pointed a tablet, a 3D model of the widened road was overlaid on the real road, allowing participants to experience the completed appearance at scale. This initiative was well received by residents, with comments such as "easy to grasp the image" and "reduced concerns," contributing to smooth consensus.

These cases show that AR civil engineering is innovating various site scenes. The key points are that it is intuitive even for non-experts and allows real-time comparison of reality and virtual models on site. By covering parts that formerly relied on experience or imagination with technology, AR enables a site environment where anyone can make accurate judgments.

Key Points for Introducing AR Civil Engineering

When introducing AR civil engineering into actual projects, there are points to keep in mind. From technical preparation to operational tips, they are summarized below.

• Prepare compatible devices and apps: First, provide smartphones or tablets capable of AR display. Many recent iPhone and Android devices support AR features (ARKit or ARCore). Some higher-end models are equipped with LiDAR sensors, which facilitate environment scanning. Also, adopt construction-oriented AR display applications. Various apps can load and display design data (3D models or drawings) in AR.

• Ensure high-precision positioning technology: To perform accurate alignment with AR over a wide site, the device's GPS accuracy alone is insufficient. Use GNSS receivers or RTK (real-time kinematic) services that enable centimeter-class positioning (half-inch-class accuracy). Specifically, options include small RTK-GNSS devices that can be attached to smartphones or using CLAS correction information provided by the domestic GNSS "Michibiki." Acquiring high-precision positioning minimizes the discrepancy between AR models and reality.

• Prepare 3D data and drawings: For AR content, basic inputs are the project's design 3D models and CAD data. However, advanced 3D data are not always necessary. Even if only 2D drawings are available, you can convert a plan into a simple 3D model by giving thickness information or project it flat onto the ground to confirm positional relationships. Also, overlaying design information onto point cloud data obtained by LiDAR scanning the current conditions can be highly effective. The key is to process the data into a form useful on site and load it into the app in an appropriate format.

• On-site calibration: When overlaying AR models onto reality, begin with "alignment of reality and virtual (calibration)." Methods include placing markers on the ground as references or aligning using known point coordinates. Here again, high-precision positioning tools allow quick and accurate alignment. Once initial settings are properly done, AR will track automatically and maintain stable displays.

• Inform and train site staff: While AR tools are often intuitive, it is important that everyone on site understands their benefits and cooperates in their use. Conduct short demos or practice sessions before introduction to share "how it appears" and "how it helps." Fortunately, recent AR systems are easier to operate without specialized knowledge, and there are cases where site workers mastered usage after only a few hours of instruction. By gradually implementing the system and incorporating site feedback, adoption will proceed smoothly.

With these points in mind, introducing AR civil engineering is by no means difficult. Especially regarding high-precision positioning, where specialized surveyors or expensive equipment were traditionally required, simple surveying solutions that anyone can use with a smartphone have emerged in recent years. The next section touches on one such new technology, simple surveying using LRTK, and considers future prospects.

Towards AR Civil Engineering Accessible to Everyone: Future Prospects and the Use of Simple Surveying

AR civil engineering is no longer limited to advanced sites; it is spreading across the industry. The keys to wider adoption are ease of use for anyone and lower-cost required equipment. One notable solution is simple surveying using LRTK.

LRTK (lightweight RTK positioning) consists of a small GNSS receiver that attaches to a smartphone, along with a dedicated app and cloud service, forming an integrated high-precision positioning and AR tool. Traditionally, high-precision surveying and positioning required total stations or survey GPS and skilled operators. But with LRTK, attaching a device to a smartphone and following on-screen guidance makes it possible for anyone to easily achieve centimeter accuracy (half-inch accuracy) positioning. Collected point coordinates are recorded and shared on the cloud instantly, enabling one-stop workflows such as accurately projecting AR models onto measured positions.

Thanks to such simple surveying technologies, AR civil engineering will become even more accessible. Since required-precision data can be obtained on site without specialized knowledge, small-to-medium projects and local government sites can adopt AR more easily. For example, tasks that used to require time and cost for arranging surveying can be handled by site personnel themselves using LRTK to measure points and immediately overlay drawings in AR. This improves efficiency and helps address labor shortages, allowing limited staff to perform high-quality construction management using digital technologies.

In the future, these AR civil engineering tools are expected to evolve further and integrate more construction processes with digital workflows. As the real and digital on-site worlds become seamlessly connected, practices that relied on "intuition and experience" will shift to data-driven smart construction, making waste-free and sustainable construction the norm. The use of AR technology and simple surveying will undoubtedly be indispensable elements for environmentally friendly and efficient future construction sites.

FAQ

Q: What preparations and equipment are needed to introduce AR civil engineering? A: Basically, you need a smartphone or tablet that supports AR display and a dedicated app that can display design data. For accurate alignment of virtual models on wide outdoor sites, centimeter accuracy (half-inch accuracy) GNSS positioning systems are desirable. Recently, solutions that bundle small RTK-GNSS receivers attachable to smartphones with apps (e.g., LRTK) have emerged, allowing high-precision positioning without specialized skills. Additionally, higher-end iPhone or iPad models include LiDAR sensors, and combining on-site terrain scanning with LiDAR can improve AR overlay accuracy.

Q: Can the use of AR technology really enable environmentally friendly construction? A: Yes. By using AR to significantly reduce unnecessary excavation and rework, operating hours for heavy machinery and the volume of waste can be reduced accordingly. For example, cases where additional excavation and backfilling were required due to design errors or oversights can be prevented with AR, eliminating such redundant work. As a result, fuel consumption and CO2 emissions are suppressed. Moreover, the risk of accidentally damaging nearby buried utilities is reduced, helping prevent environmental pollution and resource loss. Introducing AR civil engineering is a step toward eco-friendly and sustainable construction by improving on-site efficiency.

Q: What is LRTK? How does it differ from conventional surveying equipment? A: LRTK is a cutting-edge high-precision positioning solution used in combination with a smartphone. By attaching a small RTK-GNSS receiver to a smartphone and using a dedicated app and cloud service, you can obtain position information within an error range of a few centimeters (a few inches) without traditional specialized surveying equipment. Conventional total stations and GPS surveying required qualifications and skilled operators, but LRTK allows intuitive operation so anyone can perform surveying and positioning. Another major feature is that acquired data can be shared via the cloud and used immediately for AR display on site. In other words, LRTK enables a single person to handle the workflow from surveying to AR visualization, dramatically improving site productivity.

Q: Is AR civil engineering effective for small-scale projects or rural sites? A: Yes, it is highly effective. In fact, sites with limited personnel and budgets can benefit greatly from the efficiency gains of AR civil engineering. For example, even small road repair works can benefit from AR by sharing the completed image in advance, facilitating smoother communication with residents and preventing disputes. In sites with labor shortages where one person may take on multiple roles, using AR to constantly compare design with actual conditions helps reduce human errors. The advantage of being able to intuitively confirm information on site is common regardless of scale, so AR technology is effective in all kinds of projects.

Q: I’m worried whether site workers can master AR. Are special skills or training required? A: Recent AR tools are user-friendly and many can be used intuitively simply by pointing a smartphone camera at the site. Therefore, site staff can generally operate them after learning basic operations. In practice, there are increasing cases where workers routinely use AR apps without lengthy prior training. However, conducting a short briefing or demo at the introduction stage so everyone understands how AR appears and how to use it will make adoption smoother. Once they experience the benefits, workers tend to accept AR’s convenience and start using it voluntarily.