LRTK Changes Volume Calculation: Simplified Measurement and Streamlined Earthwork Management with High-Precision Positioning

Table of Contents

• The Importance of Volume Calculation in Civil Engineering

• Traditional Volume Measurement Methods and Their Challenges

• Field Measurement Transformed by High-Precision Positioning (GNSS/RTK)

• Streamlining Volume Calculation with LRTK

• LRTK Use Cases in Civil Sites (Cut, Fill, Spoil, Slopes, etc.)

• Summary: How LRTK Transforms Earthwork Management

• FAQ

The Importance of Volume Calculation in Civil Engineering

Volume calculation is the process of determining the capacity (volume) of an object or space. In construction sites, this generally refers to calculating the volume of soil or materials—so-called earthwork—and is often expressed in cubic meters (m³). In civil engineering works, calculating volumes (quantities of earthwork) is an indispensable task. For example, knowing how much soil was placed in embankment works (the volume of fill), how much soil must be removed in excavation (the spoil produced by cut), the surface area of slopes, and the volumes or areas of roads and paved zones are all essential for construction planning and cost control. These measurement results directly affect schedule management and as-built verification, and they are important evidence for client reporting and progress-based payment settlements. If the accuracy of volume calculation is low, it can lead to material ordering mistakes causing shortages or surpluses, cost overruns, and discrepancies with design quantities. Therefore, civil sites require quick and accurate earthwork measurement with minimal effort.

In recent years, the Ministry of Land, Infrastructure, Transport and Tourism’s promotion of i-Construction (ICT-enabled construction) has facilitated the adoption of ICT and 3D data in construction management. New technologies such as drone photogrammetry and 3D scanners have emerged, but they are not always convenient for everyday field use. Against this backdrop, automated measurement using high-precision positioning technology based on GNSS (GPS) has attracted attention. Compared to conventional methods, efficient digital surveying is poised to revolutionize earthwork management on job sites.

Traditional Volume Measurement Methods and Their Challenges

Although volume measurement is important, the methods used until now have never been simple. Traditional civil surveying typically involved manually measuring many points with instruments like total stations or levels, then returning to the office to draft plans and calculate volumes. A typical approach was to create many cross-sections and calculate earthwork using the average-end-area method from those section areas. However, such volume calculations required skilled technicians and enormous effort. Measuring repeatedly with long tapes and spirit levels, calculating each cross-section’s volume using prism or end-area formulas, and summing them up is cumbersome. On flat, regular terrain you can compute volume as length × width × depth (cubic meters), but actual sites have undulations and slopes, so simple calculations often don’t apply. Accurate quantities require many survey points to capture the terrain in detail.

Optical total stations are heavy and take time to set up and measure, so surveys typically required multiple people. After surveying, data must be processed and volumes computed in CAD or other software. These manual tasks take days and cost money, and slope measurements raise safety concerns for workers. Conventional standalone GNSS (GPS) is convenient but has errors on the order of meters, making it unsuitable for civil surveying. Drone photogrammetry and terrestrial LiDAR point-cloud measurement have also emerged, but they demand expertise, expensive equipment, and significant data processing time, making them less accessible for quick field use. Traditional volume measurement methods are limited in terms of manpower, accuracy, and post-processing, and the field needs a more convenient and accurate approach. Moreover, because traditional methods are labor-intensive, surveys are infrequent, so shortages or surpluses during intermediate stages can go unnoticed until late in the project, risking costly adjustments.

Field Measurement Transformed by High-Precision Positioning (GNSS/RTK)

Digital surveying that leverages satellite positioning technology has become more widespread. Using a GNSS receiver (Global Navigation Satellite System, the general term for satellite-based positioning systems, including GPS), you can obtain latitude, longitude, and altitude anywhere on Earth. However, standalone positioning typically produces meter-level errors and is therefore unsuitable for civil applications. RTK (Real Time Kinematic) is a correction technology used for high-precision positioning. RTK-GNSS surveying uses correction data from base stations and high-precision augmentation services delivered by Japan’s Quasi-Zenith Satellite System “Michibiki” (such as CLAS) to dramatically improve positioning accuracy in real time. As a result, satellite positioning can determine ground point coordinates with accuracy within a few centimeters. Elevation information is obtained simultaneously, so without separate leveling surveys you can instantly calculate fill and cut volumes from height differences relative to a reference surface.

By using the coordinate data obtained from such high-precision positioning, many measurement tasks can be streamlined. Measuring multiple points in the field lets you automatically calculate distances between points and the area enclosed by multiple points. If you can record the terrain’s three-dimensional shape in detail, calculating the volume difference relative to a reference surface (i.e., earthwork) becomes easy. Tasks that once required artisan skills—area and volume calculations—are increasingly delivering immediate results on site thanks to high-precision GNSS. Furthermore, GNSS surveying allows free movement of equipment as long as the sky is open and signals are receivable, enabling rapid measurement of many points across large sites without worrying about line of sight as with optical instruments. For these reasons, GNSS-based digital surveying has become a very practical solution in civil engineering. Note that the Ministry of Land, Infrastructure, Transport and Tourism’s i-Construction initiative also promotes as-built management using high-precision GNSS, and traditional field surveying practices are beginning to change significantly.

Streamlining Volume Calculation with LRTK

Making the high-precision GNSS positioning described above even easier to use in the field is the solution called “LRTK.” LRTK is a system in which a pocket-sized RTK-GNSS receiver is attached to a smartphone or tablet; launching a dedicated LRTK app lets you use centimeter-level high-precision coordinates in real time from satellite signals. A notable feature is that even in mountainous areas without cellular coverage, the receiver can directly obtain augmentation signals from Japan’s Quasi-Zenith Satellite System, enabling stable centimeter-level positioning. Each measured point is automatically recorded in the app and can be used immediately for on-site area and volume calculations. For example, if you measure multiple GNSS points along the terrain outline, the app automatically computes the area enclosed (displaying both the horizontal projected area and the actual sloped surface area instantly). With LRTK, area and volume calculations that used to require returning to the office for specialized software can be executed on site in real time.

LRTK can also be combined with a smartphone’s LiDAR scanner to capture point cloud data (3D scan data) of soil and terrain on site. Because the LRTK device continuously corrects the smartphone’s position to cm level accuracy (half-inch accuracy) during scanning, walking around while scanning does not introduce distortion or misalignment in the point cloud. From the acquired 3D data you can instantly compute the area or volume of any selected region and display the values on the screen. Simply selecting the measurement area with a fingertip and tapping a button can deliver results like “this embankment is ○○ cubic meters” in an instant, allowing immediate understanding of as-built volumes. For wide areas beyond LiDAR range, there is a function to estimate approximate volumes by placing multiple positioning points while using AR visualization on the smartphone screen. Because calculations that once required PC-based post-processing can be completed on site with LRTK, the efficiency gains are substantial. For example, earthwork measurements that traditionally took half a day to compute from elevations and cross sections can be measured on site in about 10 minutes with LRTK, with calculation processing taking only a few seconds. The fact that a single worker can perform high-precision surveying and calculations with a smartphone plus an LRTK device weighing only a few hundred grams is truly next-generation civil surveying.

LRTK Use Cases in Civil Sites (Cut, Fill, Spoil, Slopes, etc.)

Introducing LRTK streamlines volume measurement and earthwork management across many civil site operations. Below are representative application scenarios.

• Slope area and earthwork measurement: For slopes on retaining walls or developed ground, measuring surface area and earthwork is required. With LRTK you can scan sloped terrain from a safe distance in a short time and calculate accurate slope surface areas and the amount of earth contained in those slopes. Previously, workers sometimes entered slopes and measured with tape measures despite the danger, but LRTK enables non-contact measurement and improves safety. Since both the measured sloped surface area and the horizontal projected area are calculated on the spot, it helps estimate the area of weed-control sheets or the quantity of shotcrete needed. You can also quickly verify on site whether the constructed slope meets the design gradient and shape, streamlining as-built inspections.

• Fill works earthwork management: In roadworks or land development where fill is placed, accurately knowing the volume of imported soil (fill quantity) is important. Scanning the finished fill with LRTK lets you instantly calculate fill volume from the height difference relative to the original ground. Daily tracking of fill volumes enables smooth progress management and quantity reporting, making overall earthwork management more transparent. Traditional workflows involved measuring heights using batter boards or stakes and comparing them to drawings, which introduced time lags. With LRTK, real-time on-site confirmation of fill quantities prevents rework and reduces material surplus or shortage losses.

• Verification of paved area as-built and thickness: For road paving and concrete works, area measurement of the work zone and verification of finish thickness are essential for quality control. With LRTK, simply walking the perimeter of a paved area and measuring points lets you calculate accurate planar area. If ground elevations before and after paving are measured with GNSS, you can compute the material volume from the pavement thickness. Even for large parking lots or roads, a single person can quickly obtain area and thickness as-built information, greatly reducing inspection workload. Real-time measurement allows immediate detection and correction of shortages or excesses right after construction, facilitating quality assurance.

• Verification of spoil and backfill quantities: LRTK is also valuable for determining the quantity of spoil generated by excavation or inventory volumes of piled soil and aggregate. Historically, volumes of piled soil were sometimes roughly estimated by probing heights and using empirical rules. With LRTK you can scan the pile to capture its accurate 3D shape and compute its volume. This enables on-the-spot decisions like “how many more truckloads of spoil will be produced” or “how many cubic meters are in stock.” Accurately knowing spoil volumes helps prevent over- or under-ordering of trucks and supports safety and environmental controls such as preventing overloading and illegal dumping. On sites where excavation and backfilling repeat, you can immediately measure and compare the day’s cut and fill volumes on site, simplifying planning for soil transport.

Summary: How LRTK Transforms Earthwork Management

Methods for volume calculation in civil construction are rapidly changing thanks to new technologies like LRTK. Combining high-precision GNSS with a smartphone, LRTK dramatically streamlines earthwork measurement and calculation that used to require time and manpower. When complex terrain surveying and earthwork computation can be completed almost in real time on site, the PDCA cycle of construction management accelerates and more efficient earthwork planning becomes possible. The benefits—improved as-built management and quantity reporting accuracy, enhanced worker safety, and reduced rework—are significant.

LRTK’s simple surveying is also attractive because site staff, not only specialized surveyors, can intuitively operate it. Because the entire process from measurement to data processing and result sharing can be digitized, LRTK becomes a powerful tool to drive DX (digital transformation) in civil construction. With aging and shortages among skilled surveyors, LRTK is expected to contribute to labor saving and skill transfer. If high-precision volume calculation becomes routine, much of the stress and waste associated with earthwork management can be substantially reduced. LRTK Changes Volume Calculation—experience these benefits on your site. Such smart surveying technologies will increasingly take center stage in the future of civil surveying.

FAQ

Q. What is LRTK? A. LRTK is a high-precision GNSS positioning system used in conjunction with smartphones or tablets. A pocket-sized GNSS receiver is attached to the device and a dedicated app acquires centimeter-level positioning. It’s a solution that enables convenient, accurate surveying without heavy survey instruments or specialized equipment.

Q. How accurate is measurement with LRTK? A. LRTK uses RTK technology to reduce positional errors to a few centimeters. While typical smartphone GPS has meter-level deviations, LRTK achieves measurement accuracy suitable for civil engineering. Vertical accuracy is also high, making it reliable for assessing fill and cut volumes that were previously difficult to quantify.

Q. Can it position in mountainous areas without cellular coverage? A. Yes. LRTK receivers can directly receive augmentation signals (such as CLAS) from Japan’s Quasi-Zenith Satellite System (Michibiki), enabling high-precision positioning even where mobile phone signals do not reach. Stable surveying accuracy can be maintained on sites where internet-based base station corrections are unavailable.

Q. How does it compare to traditional surveying or drone measurement? A. LRTK does not require setup or multi-person operation like a total station; one person can complete a survey simply by walking the site, which is a major advantage. Unlike drone photogrammetry, it does not require flight planning, approvals, or long data processing, and delivers immediate measurement results. It’s ideal for routine progress tracking and as-built verification when you need fast, on-the-spot answers.

Q. Can people without special skills or qualifications operate it? A. Yes. LRTK is designed for ease of use in the field: operating the smartphone app following on-screen guidance requires no specialized surveying knowledge. Initial setup and basic measurement methods are intuitive, and site staff can start using it after short training. Acquired data can be automatically saved and shared to the cloud, so anyone can easily review results.

Q. Can data obtained with LRTK be used later? A. Yes. Survey data recorded in the LRTK app can be integrated with cloud services. Points and point clouds uploaded from the field are immediately viewable on office PCs. Acquired data can be reviewed in a browser-based 3D viewer, and distances, areas, and volumes can be recalculated later. Survey results can be exported as CAD data (DXF, etc.) or as photo-attached PDF reports, facilitating creation of as-built drawings and quantity reports. The ability to streamline everything from field measurement to data sharing and document creation is another major benefit of LRTK.

Q. What do you need to use LRTK? A. You need an LRTK receiver (compact GNSS antenna) and a compatible smartphone or tablet. Currently it supports iPhone and iPad; installing the dedicated LRTK app (free) and attaching the device completes setup. Then, outdoors with a clear view of the sky, launch the app and walk the area you want to measure to begin high-precision surveying. When internet is available, base station correction data can be used, but even without connectivity you can maintain accuracy using the Michibiki satellite augmentation mentioned above.