A New Era of Preliminary Quantity Estimation Opened by Smartphone Surveying

For architects and civil engineers, preliminary quantity estimation is a critical process in the early stages of a project. This phase—where building or earthwork volumes are roughly calculated to assess construction costs and the feasibility of plans—demands both accuracy and efficiency. Recently, an innovation has emerged in how preliminary quantity estimation is conducted: easy, high-precision surveying using smartphones, commonly referred to as smartphone surveying. In particular, a new technology known as LRTK (described below) enables centimeter-level positioning with a smartphone, allowing anyone to quickly and accurately quantify site conditions in the field. We are truly entering a new era of preliminary quantity estimation.

This article covers the basics and importance of preliminary quantity estimation, reviews the challenges of traditional methods, explains how smartphone surveying addresses those challenges, and outlines the principles and use of LRTK. It also presents concrete use cases in both architecture and civil engineering, and considers the benefits available to small offices and site teams. Finally, we look ahead to BIM integration and automated estimating, and discuss the potential unlocked by LRTK’s simple surveying capabilities. Let’s explore how smartphones and LRTK are changing the world of preliminary quantity estimation.

Basics and Importance of Preliminary Quantity Estimation

“Preliminary quantity estimation” is a design practice used in a project’s early stages to calculate the rough quantities needed and incorporate them into planning and pricing. In architecture, this includes values such as gross floor area, structural volume, and the area of finishing materials; in civil engineering, it includes cut-and-fill earth volumes, pavement areas, and pipe lengths. These are calculated from design drawings and site surveys. This process is the familiar quantity takeoff, where multiplying the estimated quantities by unit prices yields a preliminary construction cost estimate.

The accuracy and reliability of these preliminary estimates are extremely important. If early estimates are appropriate, securing project budgets and deciding design direction become smoother, reducing rework. Conversely, incorrect quantity estimates can lead to later design changes or budget overruns, posing a risk to the entire project. Therefore, it is desirable to obtain the most accurate quantities as early as possible and to perform preliminary quantity estimation efficiently.

Recently, public-sector procurement has been experimenting with a procurement method based on preliminary quantity estimation. In this approach, detailed drawings are omitted in the initial design, some construction quantities are procured on the basis of preliminary estimates, and the contractor performs detailed design after contract award to refine and finalize quantities. While this reduces design effort and enables earlier awarding, the uncertainty in initial estimates requires measures to minimize under- or over-estimation. In any case, early quantity understanding remains a key to project success, which draws attention to more accurate and easy surveying methods. The next section examines the challenges of conventional preliminary quantity estimation processes.

Challenges in Traditional Preliminary Quantity Estimation

Traditionally, various constraints and issues arose when calculating preliminary quantities. The major problems include:

• Accuracy limits from estimating based on drawings: In early design stages, quantities are often inferred from limited information such as plans and typical sections, which cannot fully reflect detailed existing topography or structures. For example, estimating earthwork volumes based on elevation differences inferred from a few sections can produce quantity errors if the real terrain differs.

• Inefficiency from outsourcing surveying work: Outsourcing to obtain accurate field elevations and dimensions takes time and money. For small projects or early stages, teams often hesitate to outsource surveying and may proceed with uncertain values.

• Insufficient accuracy of simple measurement methods: Skipping surveying or substituting handheld GPS units or tape measures results in large positional errors; centimeter-level accuracy is not achievable. Conventional smartphone GPS typically has errors of several meters, making it impractical for construction uses.

• Design rework due to quantity discrepancies: If preliminary quantities remain inaccurate, discrepancies discovered during detailed design or construction require design changes and budget adjustments. This creates rework, increasing project cost and risking schedule delays.

Because of these issues, traditional preliminary quantity estimation has struggled to balance “speed” and “accuracy.” Even when early detailed understanding is desired, traditional methods are often too cumbersome to be realistic. How does smartphone surveying change these problems?

Practical Improvements Enabled by Smartphone Surveying

Introducing smartphone surveying offers groundbreaking improvements to these challenges. Combining a smartphone with high-precision positioning technology brings the following benefits to preliminary quantity estimation:

• Rapid data acquisition: Smartphone surveying allows on-the-spot measurements whenever needed. There is no need to arrange a dedicated survey crew—designers themselves can quickly capture site dimensions and elevation differences. Values measured on site can immediately be reflected in preliminary quantity calculations during the early planning stages, accelerating project startup.

• Centimeter-level accuracy: High-precision positioning once difficult to achieve is now possible with smartphone + LRTK. Using RTK-GNSS corrections, smartphones can perform surveying with errors of only a few centimeters or less, accurately capturing subtle terrain variations and structure heights. This dramatically improves the accuracy of preliminary estimates and moves practitioners away from relying on intuition and experience.

• Low cost and low barriers to entry: Equipment for smartphone surveying is simply a commonly used smartphone and a compact positioning receiver. Compared to traditional surveying instruments (total stations or large GNSS units), the cost is overwhelmingly lower, and there is no heavy equipment to transport or power. Intuitive app operation means staff without specialized training can use it, lowering the barrier to field adoption.

• Digital data sharing: Survey data captured on a smartphone can be uploaded to the cloud or shared by email or chat immediately. Coordinate points, photos, and notes can be viewed by the whole team right away, eliminating the need to wait until returning to the office to produce drawings. This enables rapid alignment on site conditions and reduces communication losses with downstream processes.

In addition, smartphone surveying supports a variety of measurement types. Beyond single-point distance or height measurements, smartphone cameras and LiDAR can be used to produce 3D scans and point clouds from which areas and volumes can be automatically computed. Detailed 3D information captured with centimeter accuracy lets designers visualize quantities and spatial relationships that were previously invisible. In these ways, smartphone surveying significantly improves the speed, accuracy, and usability of preliminary quantity estimation.

What Is LRTK? Technology That Turns a Smartphone into a High-Precision Surveying Instrument

LRTK is a high-precision positioning solution consisting of a small GNSS receiver that attaches to a smartphone and a dedicated app. It applies real-time correction technology known as Real Time Kinematic (RTK) to enable centimeter-level surveying with a smartphone alone. In other words, a smartphone in your pocket can effectively become precision surveying equipment.

Usage is simple. Attach the dedicated small receiver (antenna unit) to the smartphone, launch the LRTK app, and point the device at the location you want to measure. For a single-point coordinate measurement, just point the smartphone at the spot and tap a button in the app to instantly record high-precision latitude, longitude, and elevation. The app also automatically saves date/time, point name, and satellite reception status, and can convert coordinates to national or regional coordinate systems (e.g., plane rectangular coordinates and elevation datum) if needed. It’s like replacing pen-and-paper note-taking with a smartphone that handles everything.

LRTK offers a wide range of functions to meet field surveying needs with a single device. In addition to single-point coordinate measurement, it supports continuous positioning mode to record many points while walking, and it can use the smartphone’s LiDAR sensor to 3D-scan the surroundings into a point cloud. The captured point clouds are georeferenced in a global coordinate system, allowing them to be treated as accurate, distortion-free models of existing conditions. The app can also calculate distances between measured coordinates and the area/volume of enclosed regions in real time, automatically tag photos with coordinates, and—via AR—display design models on-site for virtual layout marking and position guidance. With these all-in-one capabilities, LRTK lets users intuitively perform surveying and measurement tasks that previously required multiple instruments and workflows, using only a smartphone.

Use Cases of LRTK in Architecture

In architectural design, smartphone surveying and LRTK are powerful tools for site surveys and renovation/extension planning. Here are two cases illustrating their benefits.

Rapidly Grasping Volume with Site Surveying

Imagine an architect given a new project site. Traditionally, time would be spent arranging survey drawings or checking existing documents, and construction-possible volumes would be estimated from limited plan information. With an LRTK-equipped smartphone, the architect can visit the site and quickly measure key dimensions and elevation differences. For example, measuring several boundary points on the spot to create a rough site plan, or taking multiple elevation points to calculate average slope are easily doable. As a result, designers can establish site-adapted plans for building placement and scale (volume) from the early stages. With site data accurate to within centimeters, the required earthwork for site preparation and cut-and-fill balance can be understood early, reducing the risk of later design changes.

Measuring Existing Buildings to Inform Extension Plans

When planning an addition or renovation to an existing building, smartphone surveying is also a strong asset. Designing an addition requires accurate dimensions of the existing building—wall positions, eave heights, and opening heights—as well as surrounding space conditions. Measuring key points with an LRTK-enabled smartphone quickly yields these values. If needed, scanning the whole building into a 3D point cloud with coordinates allows the team to review details in the office later while refining the addition design. Data like this helps ensure the interfaces and connections between old and new structures are dimensionally accurate, reducing on-site fitting work during construction. AR features can also overlay the virtual addition model on the existing building through the smartphone, enabling on-site checks of volume and design harmony and strengthening proposals to clients.

Use Cases of LRTK in Civil Engineering

In civil works, smartphone surveying greatly aids early-stage quantity assessments. Representative cases include earthwork estimates for land development and quantity checks for landscaping and piping works.

Earthwork Estimation for Development Sites

Planning land development or residential land formation requires understanding current terrain to estimate cut-and-fill volumes. Traditionally, terrain survey maps and a few sections used with the average section method were common, leaving room for accuracy concerns. With an LRTK-capable smartphone, you can walk the planned area, measure many elevation points yourself, and create a current terrain model. From the resulting point cloud or mesh model, you can immediately compute cut-and-fill volumes by comparing with the designed final ground surface. For example, performing an on-site simulation—“If we grade to this elevation, the earthwork will be approximately XX cubic meters”—helps examine earthwork balance during the planning stage. This prevents planning mistakes such as excessive spoil or insufficient fill and optimizes earthwork plans.

Quantity Checks in Landscaping and Piping Works

For landscaping (paving parking lots, garden work, etc.) and underground piping, smartphone surveying assists quick quantity checks. For example, walking the parking area while measuring can instantly provide an accurate square meter value even for complex shapes, improving material quantity estimates. When routing pipes within a site, continuous ground elevation measurement can create a simple longitudinal profile to check proper slopes and burial depths. Recording the coordinates of manholes and existing pipes avoids discrepancies between drawings and actual conditions and helps calculate pipe lengths and excavation volumes.

In civil fields, smartphone surveying makes routine on-site quantity calculations something teams can do themselves. Tasks once entrusted to specialist survey crews—terrain surveys and as-built verifications—can now be performed quickly by construction managers, significantly speeding up planning. This leads to schedule acceleration, improved cost control accuracy, and overall site efficiency improvements.

Design Support Methods That Integrate Quantities and Space

Advances in smartphone surveying and digital measurement technologies now make it possible to treat quantities (numeric data) and space (site 3D information) as an integrated whole. Traditionally, quantity calculations were numerical tasks based on drawing dimensions, separated from spatial understanding. But with LRTK, you can capture space itself as 3D data and directly derive necessary quantities from it. For example, scanning a site into a point cloud records terrain and structures as a digital model, from which volumes and areas can be measured. Because quantity calculation and spatial understanding occur simultaneously, you can intuitively grasp relationships such as “how many cubic meters will be cut if this portion is excavated.”

Also, overlaying a design model on captured existing-condition data makes it easy to compare design proposals with on-site conditions. Some LRTK cloud services allow you to composite field-measured point clouds with design 3D models and automatically compute differences in terrain or volumes. This makes it possible to “verify quantities in space” during the design stage. On-site AR viewing of the proposed completion while checking elevation differences with the ground or immediately confirming required backfill volumes enables an integrated examination of space and quantities.

Such methods serve as powerful tools to bridge design and engineering. By visually grasping volumes that were previously hard to sense and quantifying them, designers and engineers can make decisions with firmer evidence. The “visualized” quantity information can be incorporated directly into design review, enabling planning with unprecedented speed and persuasive power.

Benefits for Small Offices and Site Teams

Smartphone surveying and LRTK technology offer significant advantages for small design firms and site construction managers with limited resources.

• Reduced initial investment and operating costs: High-precision surveying traditionally required expensive equipment purchases or outsourcing costs. With smartphone surveying, you only need a smartphone you already own and a relatively inexpensive receiver. High-precision surveying can be integrated into routine work without hiring a dedicated surveyor, providing excellent cost performance.

• Autonomy to measure on-demand: In small firms, designers can perform field surveys themselves without relying on external parties. When someone needs to confirm a dimension, they can measure on site immediately, preventing design work from stalling while awaiting survey results. Construction supervisors can also perform quantity takeoffs for progress checks or change orders themselves, responding flexibly to changing conditions.

• Ease of learning and operation: Unlike specialized instruments, smartphone-app-based surveying is intuitive and easy to use. Difficult surveying calculations and coordinate conversions are handled automatically by the app, so anyone from experienced staff to newcomers can start using it after short training. Staff who are “not survey specialists” are less likely to resist using the tool, which raises the overall skill level of the team.

• Data utilization and improved communication: Digitally acquired survey data can be imported directly into design software or shared internally and externally to achieve consensus. Small organizations, where information-sharing speed is crucial, benefit from cloud integration that delivers the latest site information to the office in real time, reducing communication losses between designers and builders. This enables faster decision-making and early detection and correction of errors.

In these ways, LRTK-enabled smartphone surveying provides an environment where “anyone can measure, anywhere, immediately,” dramatically improving efficiency and accuracy for small organizations and site-level operations.

Future Outlook: Laying the Groundwork for BIM Integration and Automated Estimating

The spread of smartphone surveying and LRTK will likely promote deeper integration with BIM (Building Information Modeling) and estimating systems, accelerating digitalization across construction projects. Even now, point clouds and coordinate data captured with LRTK can be easily imported into CAD and BIM models. This enables the reproduction of existing terrain in BIM for design use and the linkage of accurate location data for existing structures to design models. In the future, it may become possible for smartphone-captured data to synchronize in real time with cloud-based BIM models, creating a digital twin of design and site that is always up to date.

Furthermore, automated preliminary quantity estimation is within sight. BIM already supports automatic quantity extraction from models (5D BIM), and the addition of high-precision LRTK data will expand both calculation accuracy and applicability. For example, software could automatically compute differential earthwork volumes by comparing field point clouds with design models captured via smartphone surveying, or AI could identify scanned elements to extract material quantities. A future where captured site information is instantly reflected in estimates and manual quantity takeoffs and checks are greatly reduced is not far off.

This convergence of BIM and field surveying will standardize data across the construction lifecycle from planning through construction and maintenance. As a result, losses from design changes and quantity errors will decrease, dramatically improving project productivity and transparency. The experience and data accumulated through smartphone surveying will become a valuable asset for future construction DX (digital transformation).

Conclusion: An Era Where Anyone Can Perform High-Precision Preliminary Tasks with LRTK

The advent of smartphone surveying with LRTK is beginning to transform how preliminary quantity estimation is conducted. Early quantity assessments that once relied on plans and experience can now be performed based on accurate data measured directly on site. This approach, which balances speed and accuracy, directly enhances the efficiency and reliability of design and construction processes.

In particular, adopting LRTK as a simple surveying function enables small teams to obtain high-precision quantity data without large-scale equipment. Each person can act as a “mini surveyor,” quickly feeding field information back into the project, accelerating the PDCA cycle and enabling leaner planning.

The new era of preliminary quantity estimation is already upon us. By lowering the barrier to surveying through a familiar tool—the smartphone—precision field measurement has become a part of everyday work. Designers and engineers who have not yet experienced this technology should try smartphone surveying with LRTK to appreciate its usefulness. Riding the tailwind of an era when anyone can accurately capture quantities, let’s move toward more secure and reliable project execution.