A New Era of Preliminary Quantity Design Opened Up by Smartphone Surveying

For architects and civil engineers, preliminary quantity design is a crucial process in the early stages of a project. At this stage, where building and earthwork volumes are roughly calculated to judge construction costs and the feasibility of plans, both accuracy and efficiency are required. In recent years, innovation has occurred in how preliminary quantity design is conducted: the emergence of easy, high‑precision surveying using smartphones, so‑called smartphone surveying. Especially with a new technology called LRTK (described later), centimeter‑level positioning (inch‑level) is possible with a smartphone, allowing anyone on site to quickly and accurately grasp quantities. A true new era of preliminary quantity design is being opened.

This article covers the basics and importance of preliminary quantity design and revisits the challenges of conventional methods. It explains how smartphone surveying solves these issues and outlines LRTK and how to use it. It also presents concrete use cases in both architecture and civil engineering, and considers the benefits small offices and site teams can enjoy. Finally, looking ahead to BIM integration and automated quantity takeoff, it touches on the potential brought by LRTK’s simple surveying capabilities. Let’s explore how smartphones and LRTK are transforming the world of preliminary quantity design.

Basics and Importance of Preliminary Quantity Design

"Preliminary quantity design" is a design approach that calculates the approximate quantities needed in the early stages of a project and reflects them in planning and estimates. In architecture, this means computing values such as gross floor area, structural volume, and finish material areas; in civil engineering, it means quantities like excavation and fill volumes, pavement area, and pipe length. These are calculated based on design drawings and site surveys. It is the process commonly called quantity takeoff, and by multiplying the calculated quantities by unit prices, an approximate construction cost can be estimated.

The accuracy and reliability of these preliminary quantities are extremely important. If early‑stage quantities are appropriate, securing project budgets and setting design policies proceed smoothly, reducing rework. Conversely, mistakes in quantity estimates can lead to later design changes or budget overruns, becoming a risk for the entire project. Therefore, it is desirable to know accurate quantities as early as possible, and to conduct preliminary quantity design efficiently.

In recent years, a "preliminary quantity design procurement method" has been trialed even in public works. This method omits detailed drawings in the initial design, procures some work quantities on a provisional basis, and allows the contractor to perform detailed design after contract award to refine and confirm quantities. While this approach offers labor savings in design and earlier procurement, the initial preliminary quantities carry uncertainty, so efforts are needed to minimize under‑ or overestimation. In any case, early quantity understanding remains a key to project success. Thus, attention turns to using more accurate and user‑friendly surveying methods. The next chapter examines the challenges of traditional preliminary quantity design processes.

Challenges in Conventional Preliminary Quantity Design

Traditionally, there have been various constraints and challenges when calculating preliminary quantities. Below are representative issues.

• Accuracy limits when inferring from drawings: In early design, quantities are often estimated from limited information such as plans and standard cross‑sections, which cannot fully reflect detailed existing topography or structures. For example, estimating earthwork from a few cross‑sections to assume ground elevation differences can result in quantity errors if the actual terrain differs.

• Inefficiency due to outsourcing survey work: Outsourcing surveys to obtain accurate on‑site elevations and dimensions takes time and cost. For small projects or early stages, teams may hesitate to outsource surveying, and as a result proceed with uncertain values.

• Insufficient accuracy from simple measurement methods: Omitting surveying or substituting with consumer handheld GPS or tape measures yields large position errors and cannot achieve centimeter accuracy. Conventional smartphone‑embedded GPS has errors of several meters (several ft), making it impractical for construction use.

• Design rework due to quantity mismatches: If preliminary quantities remain inaccurate, discrepancies may surface during detailed design or construction, requiring design changes or budget adjustments. This creates rework, increasing costs and potentially delaying schedules.

Because of these issues, conventional preliminary quantity design has struggled to reconcile speed and accuracy. Even if one wants to capture details early, traditional methods are too time‑consuming to be practical. How, then, does smartphone surveying change these problems?

Practical Improvements Achieved by Smartphone Surveying

Introducing smartphone surveying offers groundbreaking improvements for these challenges. By combining smartphones with high‑precision positioning technologies, smartphone surveying provides the following benefits for preliminary quantity design on site.

• Rapid data acquisition: With smartphone surveying, measurements can be taken on site immediately when needed. There is no need to arrange a specialized survey team; designers themselves can quickly capture site dimensions and elevation differences. Even in the initial planning stage, measured values can be reflected immediately in preliminary quantity calculations, speeding up project startup.

• Centimeter‑level accuracy (inch‑level): High‑precision positioning that was previously difficult can be achieved with a smartphone plus LRTK. Using RTK‑GNSS corrections, smartphone surveying can produce measurements with errors of just a few centimeters or less (a few inches or less), accurately capturing fine terrain variations and structure heights. This dramatically improves the accuracy of preliminary quantities and moves estimates away from reliance on intuition and experience.

• Low cost and low barriers to entry: The equipment needed for smartphone surveying is just the smartphone commonly carried and a small positioning receiver. Compared to conventional surveying instruments (total stations or large GNSS machines), it is far less expensive, and there is no heavy equipment to transport or power to secure. App‑based operation that anyone can handle means even staff without specialized training can use it, making on‑site adoption very easy.

• Digital data sharing: Survey data collected on a smartphone can be uploaded to the cloud or shared via email or chat immediately. Coordinate data points, photos, and notes can be accessed by the whole team right away, eliminating the need to wait until returning to the office to create drawings. Stakeholders can quickly share a common understanding of the site, reducing communication losses with subsequent processes.

Furthermore, smartphone surveying supports a variety of measurement types. In addition to single‑point distance and height measurements, smartphone cameras and LiDAR enable 3D scanning to acquire point cloud data of terrain and buildings, from which area and volume can be automatically computed. Detailed three‑dimensional information acquired with cm level accuracy (half‑inch accuracy) makes it possible to visualize previously unseen quantities and spatial relationships. In this way, smartphone surveying greatly improves speed, accuracy, and usability in preliminary quantity design.

What is LRTK? Technology That Turns a Smartphone into a High‑Precision Survey Instrument

LRTK is a high‑precision positioning solution consisting of a small GNSS receiver device attached to a smartphone and a dedicated app. It applies a real‑time satellite positioning correction technology known as Real Time Kinematic (RTK), enabling centimeter‑level (inch‑level) surveying with a smartphone alone. In other words, a smartphone that fits in your pocket effectively transforms into a precision surveying instrument.

Usage is simple. Attach the dedicated small receiver (antenna unit) to the smartphone, launch the LRTK app, and point the device at the point you want to measure. For example, to measure the coordinates of a single point, simply hold the smartphone over that point and press a button in the app — high‑precision latitude, longitude, and elevation are recorded instantly. Date/time, point name, and satellite reception status are automatically saved with the record, and, if necessary, the data can be converted to national or regional coordinate systems (plane rectangular coordinates or height datums). Instead of taking notes with paper and pen, the smartphone takes on all those roles.

LRTK offers a wide range of features that cover on‑site surveying needs in one 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 point cloud data. Since point clouds are assigned global coordinates (earth coordinate system), they can be treated as accurate, undistorted as‑built models. The app also provides real‑time calculations of distances between measured coordinates and the area/volume of enclosed regions, automatic coordinate tagging of photos taken by the camera, and AR functions for overlaying design models on site to support virtual layout marking (layout marking) and position guidance. With these all‑in‑one features, LRTK allows surveying and measurement tasks that once required multiple instruments and processes to be executed intuitively with a single smartphone.

LRTK Use Cases in Architecture

In architectural design, smartphone surveying and LRTK are powerful for site surveys and planning for additions and renovations. Below are two cases illustrating their effectiveness.

Quickly Grasping Volume from Site Survey

Consider an architect assigned a new project site. Traditionally, a lot of time would be spent arranging survey drawings or checking existing materials, or estimating buildable volume 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, by measuring several boundary points and creating a rough site map on the spot, or measuring multiple points to compute average slope, one can easily evaluate building placement and volume potential. Because site data can be obtained with centimeter accuracy (inch accuracy), quantities such as required fill or the balance of cut and fill can be understood early, reducing the risk of later design changes.

Measuring Existing Buildings to Inform Additions

When extending or renovating an existing building, smartphone surveying is a powerful tool. Designing an addition requires accurate knowledge of the existing building’s dimensions, heights, and surrounding spaces. Measuring key points of an existing building with an LRTK smartphone allows quick acquisition of wall locations, eave heights, and opening heights. If desired, the entire building can be 3D scanned and saved as a point cloud model with coordinates, enabling detailed review in the office while refining the addition design. With such data, connections between old and new structures and dimensions of junctions can be planned without error, reducing the need for “fit‑on‑site” adjustments during construction. Additionally, AR features allow overlaying a virtual model of the addition on the existing building through the smartphone, helping to confirm massing and design harmony on site and making proposals more persuasive to clients.

LRTK Use Cases in Civil Engineering

In civil engineering, smartphone surveying also greatly aids early‑stage quantity estimation. Representative cases include earthwork volume estimation for land development plans and quantity checks for landscaping and piping plans.

Earthwork Volume Estimation at Development Sites

In land or residential development planning, estimating cut and fill volumes by understanding current topography is essential. Traditionally, engineers often approximated volumes using a few cross‑sections and the average cross‑section method based on topographic surveys, leaving accuracy concerns. With an LRTK‑capable smartphone, planners can walk the site and measure many elevation points themselves to create a current terrain model. On the resulting point cloud or mesh model, cut and fill volumes can be calculated immediately by comparing with the design finished ground elevation. For example, performing an on‑site simulation while holding up the smartphone — “If we grade to this elevation, the earthworks will be approximately XX cubic meters” — makes it easy to evaluate earthwork balance during design. This prevents planning mistakes like excessive surplus soil or insufficient fill and optimizes earthwork plans.

Quantity Checks for Landscaping and Piping Works

For landscaping (parking lot paving, garden works) and underground piping works, smartphone surveying enables rapid quantity checks. For instance, measuring a parking lot area by walking its perimeter on site yields accurate square meter measurements even for complex shapes, allowing immediate estimation of required paving and base materials. When determining pipe routes within a site, continuous surface elevation measurements by smartphone can produce a simple longitudinal profile to evaluate proper slopes and burial depths. Recording coordinates of manholes or existing pipes reduces discrepancies between drawings and the actual site, reflecting accurate pipe lengths and excavation volumes in calculations.

Thus, in civil engineering, smartphone surveying makes it possible to perform routine on‑site quantity calculations by the project team themselves. Tasks that once required a specialist survey crew, such as topographic surveys and as‑built verification, can be performed quickly by construction management staff, greatly speeding up construction planning. As a result, schedules can be advanced and cost control improved, contributing to overall site efficiency.

Design Support Approach That Integrates Quantities and Space

With advancements in smartphone surveying and digital measurement technologies, it has become possible to capture quantities (numerical data) and space (the site’s three‑dimensional information) in an integrated manner. Traditionally, quantity calculation was a task of computing numbers from drawing dimensions, separate from spatial understanding. But with LRTK, the space itself can be obtained as 3D data, from which required quantities are directly computed. For example, scanning the 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, relationships like “how many cubic meters will be removed if this part is cut by this amount” can be grasped intuitively.

Moreover, overlaying a design model onto acquired as‑built data makes comparison between the design and site conditions easy. LRTK cloud services can composite field point clouds with the designer’s 3D model, automatically calculating discrepancies in shape or volume between the planned design and existing terrain. This enables “verifying quantities in space” during the design stage. For example, while viewing an AR rendering of the finished image on a smartphone, one can check elevation differences with the ground beneath one’s feet or instantly confirm required backfill volumes — enabling evaluations where space and quantities are treated as one.

Such methods become powerful support tools bridging design and engineering. Being able to visually and quantitatively grasp volumes that were hard to sense from numbers alone allows designers and engineers to make decisions with firmer evidence. Quantified, visualized quantity information incorporated directly into design review enables planning to proceed with unprecedented speed and persuasiveness.

Benefits for Small Offices and Site Teams

Smartphone surveying and LRTK technologies offer significant benefits, especially to small design offices and site construction managers with limited resources.

• Reduced initial investment and operating costs: Previously, precise surveying required expensive equipment purchases or outsourcing costs, but smartphone surveying only needs an existing smartphone and a relatively inexpensive receiver. High‑precision surveying can be incorporated into daily operations without hiring a dedicated surveyor, delivering very high cost performance.

• Autonomy to measure on demand: In small offices, designers can perform site surveys themselves without relying on outsiders. When they need to “just check this dimension,” they can measure on site immediately, preventing design work from being stalled while waiting for survey results. For site managers, progress checks and quantity takeoff for additional works can be handled immediately in‑house, allowing flexible responses to changing conditions.

• Ease of learning operations: Unlike specialized instruments, surveying through smartphone apps is intuitive and easy to use. The app automatically handles complex surveying calculations and coordinate transformations, so anyone from veterans to junior staff can start using it after short training. Even staff who consider surveying outside their expertise can adopt it without resistance, contributing to overall team skill improvement.

• Improved data use and communication: Digitally captured survey data can be imported directly into design software or shared internally and externally to build consensus. For small organizations, rapid information sharing is crucial; cloud integration lets the latest on‑site data reach the office instantly, reducing communication loss between designers and constructors. This accelerates decision‑making and enables early detection and correction of errors.

In these ways, LRTK‑enabled smartphone surveying provides an environment where “anyone, anywhere, anytime” can survey, dramatically improving efficiency and accuracy for small organizations and site teams.

Future Outlook: A Foothold for BIM Integration and Automated Quantity Takeoff

The spread of smartphone surveying and LRTK is likely to lay the groundwork for deeper integration with BIM (Building Information Modeling) and quantity takeoff systems, further accelerating digitalization of construction projects. Even now, it is easy to import point cloud data and coordinate information obtained by LRTK into CAD and BIM models. This allows reproducing existing topography in BIM for design reflection, or linking accurate positional data of existing structures to design models. In the future, measured data from a smartphone may be synchronized in real time with cloud‑based BIM models, enabling a digital twin where design and field information are always up to date.

Moreover, automated preliminary quantity takeoff is foreseeable. BIM already has functionality to automatically calculate quantities from models (5D BIM), and adding high‑precision data from LRTK will expand the accuracy and scope of that calculation. Advanced support might include software automatically computing differential earthwork volumes by comparing site point clouds obtained by smartphone with the design model, or AI recognizing scanned elements and extracting material quantities. The information captured on site could be reflected in quantity reports immediately, greatly reducing manual quantity takeoff and checking — a future that may not be far off.

This fusion of BIM and field surveying creates continuity of data across the construction lifecycle from planning through construction and maintenance. As a result, losses from design changes and quantity mistakes will decline, dramatically improving project productivity and transparency. The experience and data accumulated through smartphone surveying will become valuable assets for future construction DX (digital transformation).

Conclusion: An Era Where Anyone Can Perform High‑Precision Preliminary Work with LRTK

The advent of smartphone surveying and LRTK is changing how preliminary quantity design is done. What was once based on plans and experience can now be done using accurate on‑site measurements. This approach, which balances speed and accuracy, directly improves the efficiency and reliability of design and construction processes.

Introducing LRTK as an easy surveying function means even small teams can obtain high‑precision quantity data without large equipment. Each person can act as a “mini surveyor,” quickly feeding site information back into the project, accelerating the PDCA cycle and enabling leaner planning.

The new era of preliminary quantity design is already here. With the smartphone lowering the barriers to surveying, precise measurement once limited to specialists can now be part of everyday work. Designers and engineers who have not yet experienced this technology can realize its usefulness by trying smartphone surveying with LRTK. Riding the tailwind of an era in which anyone can accurately capture quantities, let us move toward more secure and reliable project execution.