Table of Contents

• Introduction

• What Are Cut and Fill?

• Why Volume Calculation for Cut and Fill Is Important

• Traditional Volume Calculation Methods and Their Issues

• Volume Calculation Possible with Just a Smartphone

• Benefits of Using a Smartphone for Volume Calculation

• Why It Dramatically Improves Site Efficiency

• Introduction to Simple Surveying with LRTK

• Conclusion

• FAQ

Introduction

In construction sites and civil engineering works, cut and fill operations are routinely performed to shape the land. These tasks require accurate calculation of the volumes of soil to be removed or added. However, traditional earthwork volume calculations required specialized knowledge and were labor-intensive. Thanks to recent technological advances, it is now possible to perform cut-and-fill volume calculations with just a smartphone, dramatically improving on-site productivity. This article explains what cut and fill are, why volume calculation is important, the challenges of traditional methods, and the latest measurement techniques using smartphones and their benefits.

What Are Cut and Fill?

First, let’s clarify the terms cut and fill. Cut refers to excavating soil from hills or slopes. Cut is performed when removing elevated ground to level the site for road construction or land development. Fill refers to bringing soil to required locations and piling it up. Fill is done to raise low ground to level or to create terraces on slopes. Fill operations involve not only placing soil but also spreading it evenly (a process called shikinara-shi, or leveling) and compacting it (compaction) to form a stable subgrade.

Cut and fill are often performed together, and ideally soil excavated from cuts is reused as fill elsewhere. For example, using soil from slope cutting as fill in nearby valleys or lowlands reduces the need for disposing of excess soil or importing new soil. Therefore, balancing cut volumes and fill volumes is important from both cost and environmental perspectives.

Why Volume Calculation for Cut and Fill Is Important

From planning through completion, calculating earthwork volumes is critically important. Major reasons accurate volume calculation is required include:

• Cost and schedule management: By knowing the amount of soil to be hauled out or the amount needed for backfill, you can precisely plan truck allocation, disposal costs, and the quantity of backfill materials to procure. Inaccurate calculations can lead to soil shortages or surpluses, triggering additional work or excess soil disposal, which may cause budget overruns or schedule delays.

• Efficient construction planning: Balancing cut and fill volumes directly affects overall project efficiency. Reusing as much excavated soil as possible for fill reduces unnecessary soil transport and minimizes dump truck round trips. This also reduces environmental impact.

• Quality and safety: When placing fill, compaction reduces volume (see “soil volume change rate” discussed later). If you do not calculate fill thickness and compaction needs appropriately during planning, you risk settlement after completion or instability from overfilling. Calculations help estimate the required fill volume and post-compaction volume to ensure quality and safety.

As shown above, volume calculations for cut and fill play a crucial role in cost control and construction quality. Large discrepancies between cut and fill volumes can create problems such as handling excess soil or importing soil, so meticulous pre-planning is essential.

Traditional Volume Calculation Methods and Their Issues

Traditionally, calculating cut-and-fill volumes primarily relied on surveying data and drawings. Representative methods include:

• Average cross-section method: A basic method used in linear earthworks such as road construction. Cross-sections are taken at regular intervals, and the area of each cross-section is calculated. Multiply the average of adjacent cross-sectional areas by the distance between sections to obtain the volume for that segment. Summing segment volumes yields the total cut and fill quantities.

• Mesh (grid) method: Suitable for large sites or complex terrain. The site is divided into a grid, and the prism volume for each grid cell is calculated from the corner elevations, then summed. Compared to the average cross-section method, it handles detailed terrain variations better and improves accuracy.

These calculations assume careful field surveying. Traditionally, surveyors used transits, levels, and later total stations to obtain elevation data, then manually entered data into drawings or spreadsheets to compute volumes. In recent years, CAD software that compares 3D design models (existing terrain vs. design ground) on a PC and automatically computes cut and fill volumes has become common.

However, traditional methods have several issues:

• Burden and errors from manual work: Surveying and calculations carried out manually require significant labor and time. Large sites need many survey points and personnel. Manual calculations, drawing reading, and recording errors are common.

• Lack of real-time capability: Earthworks often require repeated volume calculations as the site progresses (for example, to check daily progress). Traditional methods require calling the surveying team and redoing data processing and calculations each time. This hinders quick decision-making and makes it difficult to respond promptly to changes on site.

• Expensive equipment and specialized knowledge: High-precision volume calculation requires high-end surveying equipment (advanced GNSS receivers, 3D laser scanners, etc.) and specialized software, resulting in high initial and maintenance costs. Securing skilled operators is also a challenge. On small sites, high costs have been a barrier to broader ICT adoption.

Volume Calculation Possible with Just a Smartphone

With advances in surveying technology, smartphones are becoming a new mainstay in civil surveying. Particularly noteworthy is the use of smartphones’ advanced sensors and positioning technologies for measuring cut-and-fill volumes. Some modern smartphones are equipped with LiDAR sensors that can scan the surrounding environment as point cloud data. Also, by supporting RTK (real-time kinematic), an augmentation to GNSS satellite positioning, smartphones can obtain positional information with centimeter-level accuracy.

Combining these features makes it possible to achieve high-precision surveying—previously requiring dedicated instruments—with just a smartphone. Specifically, by simply walking around the site with a smartphone in hand, you can:

• 3D scan the existing terrain: Use the phone’s LiDAR to scan the ground surface and record the current terrain as point clouds or 3D models. This enables rapid creation of a digital terrain model (DTM).

• Obtain high-precision coordinates: In addition to the phone’s built-in GPS, RTK enables centimeter-level positioning of the phone itself. Traditionally, smartphone GPS accuracy was about 5–10 m (16.4–32.8 ft) and unsuitable for elevation measurements, but RTK support now allows vertical measurements with approximately ±3 cm (±1.2 in) accuracy.

• Instant volume calculations: If you overlay the captured 3D data with design data within a smartphone app or cloud service, the software automatically computes cut-and-fill volumes. No tedious manual calculations or drawing interpretation is required.

The emergence of smartphone surveying has made 3D surveying and volume calculations, once reliant on specialized equipment, much more accessible. In Japan, initiatives like the Ministry of Land, Infrastructure, Transport and Tourism’s “i-Construction” program promoting ICT use have encouraged adoption of simple smartphone-based measurement even on small sites.

Benefits of Using a Smartphone for Volume Calculation

Using a smartphone for cut-and-fill volume calculation offers many benefits not found in traditional methods.

• Rapid data acquisition and calculation: Smartphone site scanning is near real-time. You can obtain volume results in the app immediately after measurement, enabling prompt on-site decisions. For example, measuring daily excavation progress with a smartphone allows timely adjustments to daily work plans.

• Labor-saving one-person surveying: Surveying that previously required multiple people can be completed by a single person with a smartphone. There is no need to transport or set up dedicated equipment or coordinate with auxiliary staff for alignment. Site supervisors or engineers can quickly perform measurements during breaks, helping address labor shortages and skills transfer.

• High precision and reliability: Don’t underestimate smartphones. With RTK support and LiDAR, measurements can reach centimeter-level accuracy (half-inch accuracy). This accuracy is comparable to that of high-end GNSS equipment and laser scanners and is sufficient for as-built control and quantity settlement. High precision reduces rework and errors, contributing to quality assurance.

• Low cost and low barriers: Smartphone surveying is far less costly than purchasing, renting, or outsourcing dedicated surveying equipment. You can start with an existing smartphone plus an app and a small peripheral device. High-performance PCs or specialized software are unnecessary; cloud services can handle data processing online. This lower initial investment facilitates ICT adoption on budget-constrained small projects.

• Data sharing and accumulation: Terrain data and calculation results captured by a smartphone are stored digitally. Uploading to the cloud enables instant sharing with office staff. There is no need to bring back drawings or notes, and accumulated historical data aids future planning and reviews.

Why It Dramatically Improves Site Efficiency

The benefits of smartphone-based volume calculation translate into site-wide efficiency gains. Here’s why.

First, there is time savings in surveying and calculation. Volume checks that once took half a day to several days due to survey team scheduling and calculation can be completed on the spot with a smartphone. This directly shortens the construction schedule and frees time for other tasks.

Next is faster plan adjustment. Earthworks change daily due to weather and ground conditions; checking volumes daily makes deviations from the plan immediately apparent. For example, if you find “there is more soil remaining than expected” or “the required excavation volume has been reached earlier than expected,” you can immediately optimize truck allocation and equipment deployment for the next day. This reduces unnecessary work and idle time, eliminating waste.

Improved communication also boosts efficiency. 3D models and numerical data visualized on a smartphone serve as common information for site staff and office personnel. Because the information is easy to understand and share, misunderstandings and transmission errors decrease, shortening meeting and reporting times.

Moreover, smartphone surveying enhances safety. Scanning steep slopes or cliff edges remotely with a phone’s LiDAR reduces the need for personnel to approach hazardous areas. Safe data collection lowers risks and contributes to smoother work progress.

In sum, smartphone-based volume calculation not only streamlines surveying tasks but also accelerates the construction PDCA cycle and transforms team workflows. It is truly a driving force for dramatically boosting site efficiency.

Introduction to Simple Surveying with LRTK

As a concrete example of technology that enables high-precision surveying with just a smartphone, here we introduce our LRTK. LRTK combines a compact positioning device with smartphones such as iPhone to provide integrated high-precision RTK positioning and 3D scanning. Attaching a dedicated device weighing just a few hundred grams to a smartphone makes centimeter-level surveying—previously requiring specialized equipment—possible.

For example, with an LRTK-compatible smartphone you can launch an app on site, scan the terrain, and calculate cut-and-fill volumes on the spot. While standard smartphone GPS suffered meter-level errors and struggled with elevation measurement, LRTK improves positioning by correcting satellite signals against multiple reference points, achieving horizontal accuracy of about 1–2 cm (0.4–0.8 in) and vertical accuracy of about 3 cm (1.2 in). This provides precise elevations for point cloud data, ensuring the accuracy required for volume calculations.

LRTK’s strengths are its high precision and ease of use. With a single tap in the smartphone app, survey data can be synchronized to the cloud, allowing office PCs to review the site’s 3D conditions or perform additional volume calculations. The device is designed to be mounted in a dedicated case attached to the smartphone, enabling stable one-handed surveying. In areas with limited cellular coverage, LRTK supports Japan’s satellite augmentation service (QZSS CLAS signal), enabling high-precision positioning even offline.

LRTK is our proprietary positioning technology and has been adopted in various construction sites as a simple smartphone-based surveying system.

Conclusion

Cut-and-fill volume calculation is an essential process for smooth construction management in civil and building works. While it used to be time-consuming and labor-intensive, the advent of smartphone-based technologies is driving significant change. High-precision surveying and instant quantity calculation with a single smartphone enable real-time decision-making and more efficient work planning on site.

Solutions like LRTK allow anyone to intuitively perform surveying without dedicated equipment, dramatically improving the speed and accuracy of earthwork management. Amid labor shortages and workstyle reforms, smartphone surveying technologies can substantially enhance site productivity.

Why not complete your cut-and-fill volume calculations with just a smartphone and aim for dramatic efficiency gains? Consider bringing this palm-sized innovation to your site.

FAQ

Q: Can a smartphone really measure cut-and-fill volumes accurately? A: Yes. With the latest smartphones and surveying apps, earthwork quantities can be measured with high precision. LiDAR-equipped phones and RTK positioning can reduce errors to a few centimeters (a few inches). RTK support also enables accurate vertical measurements that were difficult with conventional GPS.

Q: Do I need specialized knowledge or qualifications to use smartphone surveying? A: Once you learn basic operations, you can use smartphone surveying without special qualifications. Apps are designed to be intuitive so site personnel can perform volume calculations even if they are not licensed surveyors. However, if you plan to submit official survey results, a licensed surveyor may be required depending on the intended use, so please take note of applicable regulations.

Q: How does smartphone surveying compare to drone-based surveying? A: Drone photogrammetry is also widely used for volume calculations and can survey wide areas quickly. However, it requires flight permits, is affected by weather, and depends on operator skill. Smartphone surveying’s main advantages are ease of use on site and immediate results. It can be used in narrow spaces, indoors, or in no-fly zones, with minimal setup time. Choose the method that best fits the application.

Q: Can Android smartphones also be used for surveying? A: Currently, LiDAR sensors are available on certain iPhone and iPad models, but Android devices can be used with external sensors or high-precision GPS units. The key is whether high-precision positioning is achievable. Solutions using iPhone are common today, but more smartphone models are expected to support high-precision surveying in the future.

Q: How can I introduce LRTK? A: If you are considering LRTK, please contact us via our official website. We provide detailed support on required equipment (smartphone, LRTK device, etc.), initial setup, and operation. If you already have a compatible iPhone, you can start using LRTK simply by attaching the LRTK device, which makes introduction very easy. Feel free to reach out if you are interested.