Table of Contents

• Why on-site earthwork volume management is important

• Traditional methods of calculating earthwork volumes and their challenges

• Evolution of volume measurement with 3D technologies

• Emergence and benefits of smartphone-integrated surveying tools

• How one-tap instant volume calculation works

• Advantages of cloud-linked data sharing

• Realizing high-precision surveying anyone can do

• Simple surveying with LRTK

• FAQ

Wouldn’t it be extremely convenient if the volume of excavated soil or fill on a construction site could be grasped in real time as on-site earthwork volume management? In civil engineering, knowing exactly how much earth has been moved during construction, or how much more fill or cut is required, is critically important. However, traditionally it was not easy to measure and calculate volumes instantly on site. You had to call in specialist surveyors to take careful measurements, bring the data back to the office, and analyze it with drawings and software, which took time and effort before results could be obtained. Therefore, even if someone wanted to know the exact volume “right here, right now,” they often couldn’t get an immediate answer and had to rely on experience and intuition to make decisions.

In recent years, the construction industry has faced serious labor shortages and the need to adapt to work-style reforms, increasing demand for efficient construction management. In addition, the Ministry of Land, Infrastructure, Transport and Tourism–led *i-Construction* initiative is accelerating digitalization of sites (so-called site DX). Against this backdrop, expectations are rising for new tools that can measure earthwork volumes on-site in real time and enable data utilization. If on-site earthwork volume management became easy, site staff could verify as-built conditions and manage progress even without specialist surveyors, leading to improved construction productivity. Being able to know volumes immediately when needed would prevent unnecessary rework and support rapid decision-making.

Why on-site earthwork volume management is important

First, why is it important to accurately manage earthwork volumes on site? The reason is that earthwork volume data are key to decision-making and quality assurance at every stage of civil and construction projects. Below are the main situations where volume management is needed and why it matters.

• Planning construction and arranging materials: Knowing in advance how much earth will be excavated and how much fill will be required directly affects the number of dump trucks, operation plans for heavy equipment, and schedule estimates. Accurate volume information enables proper allocation of personnel and machinery and optimization of construction planning.

• As-built management and quality verification: Inspecting whether the post-construction fill and cut volumes match the design (as-built management) is indispensable from a quality assurance perspective. If there is less earth than planned, additional work is required; if there is excess, removal is necessary. Objective volume data allow early detection and correction of deficiencies.

• Cost calculation and settlement: In earthworks, cost settlements and billing are often based on the volume moved in or out. Calculating an accurate volume that both client and contractor can agree on is important to prevent monetary disputes. Settlements based on rigorous data form the foundation of trust.

• Safety management: Knowing the amounts of temporarily stored soil and the stability of slopes is also important for safety. For example, it helps judge whether temporarily piled soil is an appropriate amount or whether a fill has a shape that risks collapse. Neglecting volume management can lead to overlooking soil-related disaster risks.

As shown above, volume management is indispensable from construction planning through execution, inspection, and settlement. Whether you can obtain that information on site immediately makes a big difference in the efficiency of construction management and decision speed.

Traditional methods of calculating earthwork volumes and their challenges

However, traditional methods for grasping such volumes on site had various challenges. Historically, the following methods have mainly been used to determine earthwork volumes (fill and excavation) on site.

• Manual measurements and the average cross-section method: Site supervisors or engineers use measuring tapes and surveying staffs to measure heights and widths at several locations, create cross-sections, and calculate volumes using the average cross-section method. Alternatively, operators may estimate volumes visually based on experience, such as “about X dump trucks.” These methods, however, rely heavily on human intuition and experience and tend to produce variable accuracy. Accurate values are difficult to obtain without experienced personnel, and there is a risk of human error.

• Surveying with total stations or GPS survey instruments: Survey professionals use electronic distance meters or GNSS receivers to measure many point heights and coordinates, then analyze the data in CAD software later to calculate volumes. Although accurate, large-scale surveys often require multiple people and several days, making it difficult to get immediate results on site. The analysis also takes time, creating a time lag before volume information becomes available.

• Estimation from heavy equipment load volumes: On site, it is also common to estimate volumes from the bucket capacity of excavators or the loading capacity of dumps—e.g., “we moved X dump trucks, so about ○m³.” This is only a rough estimate and can have large errors, so it cannot be considered precise.

These traditional methods share common challenges: they are time-consuming and labor-intensive, and they lack real-time capability. You often have to wait on site for survey results, during which precise decisions or next tasks cannot proceed. The accuracy of results is also influenced by the skill of the person in charge, and with growing labor shortages, calling specialists to the site every time is costly. Additionally, surveying on steep, unstable ground can be dangerous for workers, posing safety concerns.

Evolution of volume measurement with 3D technologies

In response to these issues, new volume-measurement methods using digital technologies have appeared in recent years. A representative example is 3D surveying technology. Photogrammetry with drones and ground-based 3D laser scanners are being used to obtain detailed point cloud data (a collection of 3D coordinates) and calculate volumes.

• Drone photogrammetry: Small unmanned aerial vehicles (drones) equipped with cameras capture the site from above, and multiple images are processed to generate dense 3D models (point clouds). This method can survey entire terrains quickly even on large sites and can safely measure steep slopes where people cannot enter. Calculating volumes from the created 3D models can reduce the earthwork volume calculation time from several days to a few hours in some cases. However, drone operation requires flight permission and piloting skill and is constrained by weather conditions.

• 3D laser scanner surveying: Using large ground-based laser scanners to obtain high-precision point cloud data via laser reflection enables millimeter-level precision in terrain measurement. The reliability of volumes calculated from such data is high. However, laser scanner equipment is very expensive and requires skilled operators, making routine use by site staff difficult.

These advanced technologies have dramatically improved the speed and accuracy of earthwork volume calculations. At the same time, there is increasing demand for “an easier surveying tool that anyone on site can use.” While drones and high-performance scanners are effective, many sites struggle with their specialist knowledge requirements, permit needs, and costs. This led to the emergence of the next topic: smartphone-integrated surveying tools.

Emergence and benefits of smartphone-integrated surveying tools

Recently attracting attention are smartphone-integrated surveying tools where a small positioning device is attached to a smartphone. By combining a dedicated device and app with a smartphone that people already use, high-precision surveying has become accessible to anyone. With a smartphone-integrated tool, surveying can be completed with a pocket-sized device, truly serving as a compact surveying instrument of “one device per person.”

These smartphone-integrated tools offer various benefits.

• Ease and mobility: Because the device is compact and integrates with the smartphone, there is no need to set up tripods or transport large equipment. Workers can walk around the site holding a smartphone to survey, allowing free movement even in cramped sites or areas with elevation differences. The portability and the ability to measure on the spot whenever needed are major advantages.

• High-precision positioning: The devices attached to smartphones include high-performance GNSS (such as GPS) receivers and use correction techniques like RTK (real-time kinematic) to reduce satellite positioning errors to the centimeter level. Centimeter-level accuracy that previously required GNSS equipment costing several million yen can now be achieved with this small device and smartphone combination. GPS positioning errors of several meters from smartphone-only solutions are dramatically reduced.

• Advanced 3D measurement: The smartphone camera and LiDAR sensor (on supported models) can 3D-scan terrain and soil shapes to acquire point cloud data. Combined with the aforementioned GNSS, those point clouds are given high-precision positional coordinates, allowing the data to be handled as accurate 3D models with absolute coordinates. Calculating volume from these point clouds enables earthwork quantities to be determined with accuracy far superior to manual measurements. For example, for fills a few meters high (a few ft), you can scan thoroughly with a smartphone in a short time and compute the volume.

• Low cost and low barrier to entry: Because existing smartphones can be used, introduction costs are lower than acquiring large-scale new equipment. Intuitive smartphone operation allows site staff to start using the system after short training, even if they are not specialist surveyors. No special qualifications or complicated preparations are required, making it easy to integrate into daily construction management tasks.

The advent of these smartphone-integrated tools has introduced a surveying method that is more familiar and usable on a daily basis than drones or laser scanners. Next, let’s look at how volume management changes when using this tool.

How one-tap instant volume calculation works

With smartphone-integrated tools, the previously complex process of calculating earthwork volumes can be completed with literally “one tap.” This is because the process—from acquiring survey data to calculating volume—is highly automated and integrated.

On site, you simply launch the surveying app on the smartphone and walk around the fill or leftover soil you want to measure while holding up the phone; the surrounding 3D point cloud data are acquired in real time. After scanning the required area, you tap the “volume calculation” button in the app. Within seconds to tens of seconds, the fill or excavation volume is displayed on the smartphone screen.

This one-tap measurement is made possible by automated data processing running in the background. Traditionally, survey data had to be imported to a PC for analysis, cross-sections created in CAD software, and so on to compute volume. In smartphone-integrated tools, all these processes are executed quickly within the app. Recognition of the target’s shape from the acquired point cloud, analysis of differences from a reference plane, and volume integration all complete instantly on the smartphone.

Advantages of cloud-linked data sharing

Another major feature of smartphone-integrated tools is the ability to manage and share acquired survey data in the cloud. Once measurement is finished, the 3D model and volume data on the smartphone are uploaded to a cloud server via the internet. Office PCs and remote stakeholders can immediately view the data via a browser. Not only the measured volume values but the 3D model itself can be displayed and checked in the cloud.

This enables stakeholders to understand site conditions “even when not on site.” For example, when an on-site person measures volumes and shares them to the cloud, the head office construction manager and the client can almost immediately check the results. If needed, they can issue additional instructions or approvals right away, dramatically improving decision-making speed.

Moreover, storing data in the cloud facilitates history management and integrated management across multiple projects. You can later compare past survey data or overlay design data with current conditions to analyze volume differences. For example, overlaying the current terrain model with the design 3D model instantly shows surplus or deficit in fill/cut volumes, enabling immediate judgment on how much more earth should be moved. Regularly saving survey data to the cloud also makes it easy to remotely monitor day-to-day construction progress.

A further advantage is that the entire team can share the same up-to-date data via the cloud. Compared to relying on paper drawings or verbal reports, data-driven, smooth communication becomes possible, reducing discrepancies between site and office. Rather than stopping at measurement, a cycle of “measuring and collectively utilizing the data” can operate, further improving the efficiency and accuracy of site management. Cloud-linked volume measurement tools thus contribute not only to convenience but to faster PDCA cycles and improved quality across construction projects.

Realizing high-precision surveying anyone can do

As shown, the new surveying style enabled by smartphone-integrated tools is making “high-precision surveying anyone can do” a reality. Previously, precise surveying and volume calculation were tasks limited to specialists such as surveyors. But with smartphones, dedicated devices, and automated apps, site workers and construction management staff who are not specialists can perform surveys themselves and obtain accurate numbers. There is no need to understand complex surveying theory or formulas; following the on-screen instructions on the smartphone yields results, so even inexperienced users can operate it with confidence.

For example, veteran workers who are not used to digital devices can, after simple hands-on training, carry a surveying device in their pocket while touring the site and begin measurements on the spot—the operation is that intuitive. By holding up the smartphone and measuring with one hand, anyone can acquire centimeter-level high-precision point cloud data and calculate earthwork volumes from it. This helps address serious labor and skills shortages: consistent-quality surveys become possible without relying on experts, so younger and new staff can be productive on site while veterans can focus on higher-level management tasks.

Being “easy for anyone to use” also contributes to improved safety by reducing the need for people to enter hazardous areas alone to take measurements. For example, to measure soil piled on a steep slope, you can simply scan from a safe distance by pointing the smartphone. Quick measurements also reduce workload in hot weather or on sites with poor footing.

Additionally, the app UI is designed to be user-friendly even for those uncomfortable with IT or digital tools. With simple button operations and clear Japanese labels, users who are not tech-savvy can proceed without confusion. Even with varying IT literacy within a company, everyone can use the tool easily, aiding company-wide knowledge transfer and know-how sharing. Actual sites that have introduced such smartphone surveying tools report that “we can survey by ourselves” and “results appear immediately, making planning easier,” contributing to an overall enhancement of site capability (the combined productivity and responsiveness of the site).

Simple surveying with LRTK

So far we have looked at the latest tools that dramatically improve on-site earthwork volume management. One notable solution is LRTK. LRTK is a high-precision surveying system composed of a smartphone-integrated device and a cloud platform, developed with the concept of “easy surveying for anyone.”

Attaching an LRTK device to a commercially available smartphone instantly transforms the phone into a surveying instrument with centimeter-level accuracy (cm level accuracy (half-inch accuracy)). By combining high-precision GNSS positioning with the smartphone’s camera and LiDAR 3D scanning, the system seamlessly executes the workflow from acquiring point cloud data on site to automatic volume calculation. You can compute the volume of fills or excavation areas immediately on site, and the results are displayed instantly on the smartphone screen. Measurement data are saved on the LRTK cloud platform, making it easy to share with stakeholders or analyze in detail on a PC later.

With LRTK, you can grasp large-scale earthwork volumes with a single measurement. For example, even a soil mound several meters high (several ft) can be scanned quickly by walking around it, and an accurate volume can be calculated with one button. Because discrepancies with the amount to be removed or design values become immediately clear, site teams can promptly decide the next action (additional removal or additional filling, etc.). Where decisions previously depended on waiting for results or on intuition, LRTK promotes data-driven, efficient construction.

LRTK is not only for volume measurement but also functions as an all-in-one surveying and construction support tool, offering distance and area measurement, precise coordinate setting of control points, and AR (augmented reality) projection of design data onto the site. Because you can get the “information you need right now” on site, it becomes a reliable ally that enhances overall construction productivity and accuracy.

If you are looking for a tool to easily manage earthwork volumes on site, LRTK’s latest solutions are a strong option. Try incorporating cutting-edge digital technology into your site to realize more efficient and labor-saving civil construction.

FAQ

Q. What types of smartphone-integrated earthwork volume measurement tools are available? A. They can be broadly divided into three types. The first is the traditional manual-plus-calculation method, which has limitations in accuracy and immediacy. The second uses drones or laser scanners to calculate volumes from dense 3D data; this offers high accuracy and efficiency but requires specialist skills and equipment costs. The third, which has emerged in recent years, is the smartphone-integrated surveying device that attaches a small device to a smartphone so anyone can easily measure earthwork volumes. This type has gained attention for balancing ease of use and high accuracy.

Q. Can a smartphone really achieve centimeter-level surveying accuracy? A. Yes. Conventional smartphone-built-in GPS had errors of several meters and was not suitable for precision surveying, but attaching a high-precision GNSS receiver that supports RTK dramatically improves positional accuracy. Combining the 3D point cloud data obtained by the smartphone camera or LiDAR enables terrain measurement at the centimeter order (cm level accuracy (half-inch accuracy)). In practice, comparisons between point clouds obtained with smartphone-integrated devices and those from conventional surveying have reported errors of only a few centimeters (a few in). With appropriate device setup, a smartphone can achieve accuracy comparable to professional surveying equipment.

Q. Compared to drone surveys, what are the advantages and disadvantages of smartphone-integrated surveying tools? A. The advantage of drone surveys is that they can cover wide areas at once, making them efficient for large-scale earthworks. However, drones require flight permits, piloting skills, and are affected by weather. Smartphone-integrated tools are advantageous in that they can be used easily and routinely regardless of weather or location. They can survey small sites or urban areas immediately, and results are available on the spot. Nevertheless, for extremely large areas measured at once, drones may be more efficient, so it’s best to choose based on site scale and purpose.

Q. How can the data obtained from surveying be used? A. Point cloud data and volume calculation results obtained with smartphone-integrated tools are saved on the smartphone. With one button they can be uploaded to the cloud and viewed from an office PC via a browser, and sharing with stakeholders is easy. The data can be exported as 3D models or CSV files, so they can be used in internal reports or analyzed with other software. Comparing time-series data stored in the cloud is useful for progress tracking and streamlining as-built inspections.