Smartphone Surveying Changing Preliminary Design Methods: The Latest Trends in On-site Efficiency

Introduction: The Speed and On-site Responsiveness Required for Preliminary Design

In civil infrastructure, preliminary design (the early-stage design) is a critical process that determines the overall direction of a project and the rough cost estimate. Typically, at this stage, design proposals must be compiled and presented to stakeholders in a short period. Therefore, speed and the ability to respond on-site according to conditions are essential. For example, when sudden design changes or additional investigations are needed, the project's success depends on how quickly the site conditions can be understood and reflected in the design. Recently, DX (digital transformation) in the construction industry has progressed, accelerating efforts to strengthen collaboration between the field and design teams. One approach gaining attention in this context is smartphone surveying. This article explains the trends in efficiency smartphone surveying brings to preliminary design and introduces innovative methods for calculating earthwork volumes (volume computations).

The Importance of Grasping Earthwork Quantities in Preliminary Design

In infrastructure design, accurately grasping earthwork quantities is extremely important. In civil works, the volume of soil—such as fills and cuts for land development, road embankment volumes for road construction, excavation and backfill volumes for buried water and sewer works, and excavation volumes for structural foundations—directly affects the scale and cost of work. If earthwork quantities can be accurately understood at the preliminary design stage, the accuracy of cost estimates improves and it becomes easier to judge the appropriateness of the design. Conversely, errors in estimating earthwork volumes can lead to substantial design changes or budget overruns in later stages. For example, if the assumed amount of soil transport turns out to be larger than anticipated, additional hauling costs or securing disposal sites may be required, disrupting the overall project schedule. Thus, preliminary design requires understanding "how much earth must be moved" from an early stage. However, detailed survey data are often unavailable in early stages, creating a major challenge.

Challenges of Traditional Methods: Dependence on Surveying and Estimation Errors

In traditional preliminary design, it has been common to rely on surveying to obtain site topography information. Conducting full-scale surveys reveals accurate ground elevations and shapes, but requires arranging specialized survey personnel and equipment, which takes time and cost. Performing detailed surveys from the initial stage is difficult, so in many cases existing topographic maps or elevation datasets (such as maps or digital elevation models from the Geospatial Information Authority) were used to estimate earthwork volumes. However, these resources are not always the latest or high-resolution; they may have coarse contour intervals of 5m or 10m or fail to reflect terrain changes from past development. As a result, estimation errors of double-digit percentages are not uncommon. For instance, assuming a flat surface for calculation could lead to significantly different fill volumes when small cumulative undulations actually exist.

Moreover, traditional methods involve personnel and logistics issues. Total station surveying typically requires two-person teams at each survey point, necessitating scheduling of busy surveyors and securing on-site time. Even small field surveys often led to situations where “design cannot proceed until the survey team arrives.” Consequently, designers were forced to rely on empirical rules or safety factors for earthwork estimates without fully understanding site details, which reduced accuracy. The challenges of traditional methods can be summarized as:

• Survey cost and time: Detailed surveys require time and money, making them hard to perform casually at the preliminary stage

• Coarse data: When substituting existing materials, low resolution can miss terrain details

• Risk of reduced accuracy: Calculating earthwork from uncertain information tends to produce larger errors

• Reduced responsiveness: Unable to respond quickly to site changes or to compare alternatives (waiting for surveys)

As a solution to these challenges, smartphone surveying has attracted attention in recent years.

What Is Smartphone Surveying? An On-site Earthwork Measurement Tool Anyone Can Use

Smartphone surveying is, as the name suggests, a simplified surveying method using a smartphone. By installing a dedicated app on a smartphone, you can leverage the camera and sensors (accelerometer, gyroscope, and on high-end devices even LiDAR sensors) to measure site conditions. The primary appeal is that anyone can "measure immediately, on the spot, without special equipment."

Many smartphone surveying apps apply AR (augmented reality) technology, overlaying virtual survey poles or tape measures on the live camera view for operation. For example, by pointing the phone and placing virtual points on the ground, you can measure distances and elevation differences, or automatically calculate the area or volume of an enclosed region. No complicated operations are needed; intuitive UIs guide the user so that technicians without specialized surveying knowledge or on-site workers can use them. Because everything can be done with a single smartphone, measurement results can be displayed as graphs on the spot, saved as numeric data, and easily shared by email or cloud. This transforms a process that used to require surveying → office data processing → design update over several days into a short on-site task.

Smartphone surveying apps include various features specifically for earthwork measurement. There are modes to calculate volume by indicating the bottom and top extents of fill or excavation on the screen, modes to capture terrain cross-sections on-site and compute sectional areas and earthwork volumes, and modes to estimate area and earth volume for irregular polygons enclosed by three or more points. With just a smartphone, sufficient earthwork data can be obtained by a single operator, solving the long-standing data shortage problem at the preliminary design stage.

From Point Clouds to Earthwork Volumes: How Smartphone Surveying Affects Estimation Accuracy

An advanced aspect of smartphone surveying is that it easily captures not just single points but 3D point cloud data. A point cloud is a dataset of many measured points plotted in 3D space that can express the shape of terrain or structures in detail. While traditional surveying represented terrain with widely spaced elevation points or a few cross-sections, point clouds contain surface and volumetric information, allowing the creation of detailed models that capture subtle surface undulations.

Smartphones equipped with LiDAR scanners (for example, recent iPhone or iPad Pro models) can continuously acquire point cloud data at close range simply by pointing the camera and walking around. Even without LiDAR, photogrammetry techniques can reconstruct shapes from camera images; in either case, a 3D model of current site conditions can be generated in a short time. The workflow to calculate earthwork volumes from point clouds is as follows:

• Acquire the current point cloud: Scan the target area with a smartphone to obtain the terrain and features of fills or deposits as a point cloud.

• Compare with a reference surface: Set the design reference surface (for example, the intended finished elevation or a known ground surface) and overlay it with the point cloud data.

• Compute differential volumes: Automatically calculate fill and excavation volumes from elevation differences between the point cloud and the reference surface. Because point clouds consist of many points, the differential volume can reflect fine undulations and yield precise results.

This allows smartphone surveying to perform instant earthwork calculations using the collected point cloud data. Regarding accuracy, recent validations have reported cases where volume calculations from simple smartphone scans differed from those of high-end laser scanners by only a few percent. Of course, errors vary with environmental conditions and operator skill, but results suggest that smartphone surveying can meet the accuracy required at the preliminary design level (typically within a few percent to several tens of percent).

An important merit is the statistical strength of point clouds. Even if individual point errors are relatively large, averaging across many measured points yields accurate overall shape information. For example, deriving an average cross-section from thousands of terrain points obtained by smartphone tends to cancel out some noise and accurately capture overall terrain trends. This point cloud approach prevents the traditional problem of "oversights due to few measurement points" and provides data that directly enhance preliminary design accuracy.

Case Study: Single-person Measurement and On-site Differential Volume Calculation

How is smartphone surveying actually used in practice? Consider a road improvement project where a preliminary design needed an estimate of the cut volume for a small hill along the route. Traditionally, designers would create rough longitudinal profiles and compute volumes via average-section methods. In this case, however, a design engineer took a single smartphone to the site and completed the measurement in a short time.

The engineer walked around the hill while scanning the surroundings with the smartphone to acquire the current terrain as a point cloud. On the spot, the app overlaid a planned road elevation (design level) as a provisional plane and color-coded elevation differences with the current terrain. This made it immediately clear where and how much excavation was required to reach the design level, and the app automatically computed the differential volume (required excavation volume).

The entire process—from field scanning to volume calculation—took only a few tens of minutes, eliminating the need to return to the office for PC-based analysis. Because one person could measure and obtain earthwork quantities on site, the design team could compare multiple route options and select the optimal plan within the same day.

In another example, smartphone surveying was used for managing fill volumes of spoil at a development site. A construction manager scanned a spoil pile alone with a smartphone and confirmed the change in volume since the previous day (how many cubic meters had been removed) on the spot. This enabled flexible daily adjustments of truck counts and heavy equipment allocation according to progress, leading to more efficient construction planning.

These examples show that smartphone surveying brings on-site responsiveness: "measure when needed and get results immediately." Earthwork volumes once confirmed by cross-sections or quantity spreadsheets can now be visualized and quantified on site, enabling consistent data sharing and decision-making from planning through execution.

Toward Site-led Design: The Transformation Enabled by Smartphone Surveying

The spread of smartphone surveying is transforming the traditional office-centered design process into a site-led design approach. Previously, designers typically worked in the office with drawings while field crews followed the given plans. By using smartphones—a portable, high-level device—field staff and designers themselves can acquire data on site and feed that feedback directly into the design. In other words, the field becomes a key input source for design.

This shift brings many benefits. First, design adjustments based on actual site conditions reduce the gap between design and construction. If field personnel share data collected via smartphone surveying from the design stage onward, it becomes easier to avoid problems at the construction stage such as "things not matching the drawings" or "insufficient quantities." Also, rapid comparison of multiple design options becomes feasible. Where each option previously required separate surveying → drawing creation → quantity calculation, simulations based on smartphone survey data allow quick relative comparisons. Field constraints and terrain issues are visible from the point cloud early on, enabling the early resolution of issues that might be overlooked in the office.

Moreover, communication is revitalized. If field measurements are instantly shared via the cloud, the client, designers, and contractors can discuss using the same latest information. For example, municipal staff and design consultants can perform on-site inspections while measuring with smartphones and discuss preliminary construction costs on the spot based on the collected data. This truly makes design “field-centered,” aligning well with the i-Construction initiatives promoted by the Ministry of Land, Infrastructure, Transport and Tourism.

In short, smartphone surveying does more than improve tools—it drives innovation in the design workflow itself. By directly reflecting raw field data in the design, the boundary between field and office is increasingly blurred. This transformation simultaneously achieves faster design cycles, improved accuracy, and stronger on-site responsiveness.

Conclusion: A New Preliminary Design Workflow Starting with a Smartphone

We have reviewed how smartphone surveying improves efficiency and accuracy. Finally, let’s summarize a new workflow for preliminary design. Traditionally, the sequence was "plan based on existing materials → later reflect survey data → revise design," but going forward the following flow may become mainstream:

• Start with a field scan: A technician visits candidate project sites and scans the terrain with a smartphone to obtain up-to-date on-site data from the initial stage.

• Real-time preliminary design: Based on the point cloud and survey data acquired on site, preliminary design options are examined immediately, checking earthwork volumes and elevation differences while setting the design strategy.

• Instant feedback: Differences between provisional designs and current terrain (for example, insufficient fill or interfering terrain features) are checked on site and the design is revised as needed.

• Data sharing and consensus building: Measurement data and findings are shared with stakeholders via the cloud, fostering common understanding with the client and other departments and enabling early consensus.

• Transition to detailed design: Because high-accuracy data are available from the preliminary stage, subsequent detailed design can begin smoothly. In some cases, point clouds from the preliminary stage can be reused for detailed design or CIM models, reducing duplicated effort.

This new workflow—where "field measurement is the starting point"—eliminates the initial information bottleneck and creates a lean design process. For clients, it means receiving faster, more reliable proposals; for designers and consultants, it brings improved efficiency and competitive differentiation. For contractors, having estimators measure the site themselves to obtain accurate quantities can assist bidding strategies and construction planning.

Smartphone surveying, which dramatically enhances the speed and on-site responsiveness of preliminary design, is currently attracting attention as a leading trend in the industry. Its low learning curve makes it easy for small municipalities and SMEs to adopt, and it is expected that a bottom-up shift toward site-led design reform will continue. Why not consider adopting a smartphone-based design workflow at your organization?

Bonus: Getting Started with Simple Smartphone Surveying Using LRTK

For those who want to try smartphone surveying, a recommended solution is LRTK. LRTK is a compact RTK-GNSS receiver that attaches to a smartphone, turning it into a centimeter-level surveying device. By mounting it on an iPhone or similar device and using the dedicated app, anyone can easily acquire high-precision positional information and point cloud data. For example, with LRTK you can scan a site with a smartphone you can carry in your pocket and automatically measure distances, areas, and volumes in the cloud. Point clouds obtained are tagged with global coordinates (absolute coordinates), making comparisons with design drawings and integration with other survey data smooth.

The strengths of LRTK are its ability to greatly reduce smartphone positioning errors using a dedicated high-precision GNSS and its end-to-end convenience from measurement to data sharing. In practice, field-scanned data can be uploaded directly to the cloud and immediately viewed by office colleagues via a web browser. LRTK was developed with the goal of a "one smartphone per person" surveying setup, and both the device and app are designed to be intuitive and field-friendly.

To experience the efficiency gains of smartphone surveying in preliminary design, it’s best to start with small on-site or in-house trials. LRTK has a low initial adoption barrier and is said to be reasonably priced compared to conventional surveying equipment. If interested, check the [LRTK official site](https://www.lrtk.lefixea.com/lrtk-phone). With a smartphone and LRTK in hand, anyone can start "simple smartphone surveying" today. Try these cutting-edge tools and experience a new standard for preliminary design.