As digital transformation (DX) in civil engineering sites accelerates, it is not an exaggeration to say that the way piling work and as-built management are conducted is undergoing a major change. Tasks that traditionally required surveying equipment and many personnel—such as staking out pile positions (layout marking) and as-built inspections—can now be completed with a single smartphone. By combining high-precision smartphone positioning technology (RTK) with AR (augmented reality) and 3D scanning, solutions have emerged that digitalize and integrate the entire process from piling to as-built management. Initiatives promoted by the Ministry of Land, Infrastructure, Transport and Tourism such as i-Construction are also favorable tailwinds, and the use of ICT to advance construction management is increasingly required. The fields of piling and as-built management are no exception; this is an excellent opportunity to renew traditional methods that relied on skilled artisans with digital technology. This article explains the innovation points of a consistent workflow—from piling and staking out positions to as-built inspection—using the latest smartphone surveying technology “LRTK,” and the benefits it brings to the site.

Challenges in conventional piling and as-built management

Piling and as-built management processes have traditionally required considerable labor and personnel. For example, in staking out pile positions (the point measurement for so-called “piling”), surveyors had to use tape measures or total stations on site to mark positions based on coordinates on drawings. Tasks that require multiple people to use reference points and leveling rods, calling to one another while making fine adjustments to determine pile positions, are time-consuming and come with risks of human error. In as-built management (inspecting whether completed structures or terrain match the design), staff also needed to measure key elevations and distances with surveying instruments and then manually record and evaluate the results on paper or spreadsheet software. These tasks require advanced skill and tend to depend on specific skilled personnel (veteran surveyors), creating an issue of strong dependence on individuals. Furthermore, there has been a time lag from collecting survey data on site to bringing it back to the office for drafting and sharing, making real-time information sharing between the field and designers/managers difficult.

In the construction industry, where labor shortages are intensifying, reducing manpower for surveying tasks while ensuring construction accuracy is a major challenge. In particular, misalignment of pile positions or errors in as-built results can lead to rework in later processes or affect the performance of structures, so reliable and efficient management methods have been required. A promising key to solving these issues and updating construction management is on-site DX solutions that leverage smartphones and the latest technologies.

Innovation in piling work with smartphone surveying: RTK coordinate guidance and AR staking out

By combining smartphones and high-precision GNSS, “smartphone surveying” dramatically improves the efficiency and accuracy of staking out positions during piling. The smartphone surveying system called LRTK enables centimeter-level positioning with the RTK method. With this, design coordinates prepared in advance (pile position data from drawings) can be used on site to guide workers directly to the pile installation positions (coordinate guidance). Workers can reach designated coordinate points simply by following guides displayed on the smartphone screen. In effect, the smartphone acts as a “piling navigation” on site, allowing anyone to intuitively determine pile positions that previously required experienced skill.

Moreover, the use of AR (augmented reality) makes visualizing pile positions easy. When viewing the site through the smartphone camera, virtual piles or markings are overlaid on the screen to indicate precise positions and elevations. AR-based staking out makes it immediately clear where piles should be driven on the ground, greatly reducing the effort of marking pile centers with strings or spray paint as before. If CAD drawing data or design models (BIM/CIM) are loaded into the app, it is also possible to display life-size planned lines or structure models in AR on site and construct while referencing them. Such digital visualization enables intuitive on-the-spot confirmation of construction accuracy and interference checks with buried utilities or structures, thereby reducing operational mistakes. The combination of high-precision RTK positioning and AR staking out provides the major benefit of improving efficiency while maintaining high accuracy.

Because smartphone surveying-based coordinate guidance for piling can be performed by a single person, it directly enables reduced surveying manpower. There is no need to transport and set up heavy surveying equipment or to align positions with multiple people; with a smartphone in hand, points can be surveyed one after another, dramatically improving on-site productivity. Smartphone guidance is easy to operate and can be used by non-veterans, which helps eliminate dependency on specific individuals. Additionally, reduced work time and fewer personnel contribute to improved safety. When piling layout can be completed by a small number of people, the risk to surveyors working near operating heavy machinery is reduced, enabling a safer construction system.

Smartphone surveying also proves powerful in situations where positioning from above is difficult, such as in top-down construction methods used for underground structures (a method where the upper structure is built while the underground portion is constructed). LRTK systems have a relative positioning mode that can be used indoors or underground; using reference points obtained on the surface, the smartphone’s sensors can continue to track movement and maintain positioning even outside GNSS coverage. This enables AR-based staking to continue where GPS signals do not reach, allowing precise guidance of pile positions even under the special conditions of top-down construction sites.

Efficiency improvement in quality control through LiDAR scans and as-built heat maps

The power of smartphone surveying extends beyond piling to post-construction as-built management (quality and dimensional inspection). LRTK-equipped smartphones use built-in LiDAR sensors and cameras to rapidly perform three-dimensional measurements of completed structures and terrain on site. By conducting detailed 3D scans with point clouds, as-built measurement data with associated design coordinate frames can be obtained immediately. Overlaying this on the cloud with design data for comparison can automatically generate an “as-built heat map” that visually represents deviations.

The heat map shows elevation differences between the design surface and the measured surface, or excess/deficiency of fill thickness, using color coding that anyone on site can intuitively understand to check construction accuracy. For example, in ground leveling or embankment as-built checks, areas higher than the specified elevation can be shown in red and lower areas in blue, making it easy to grasp excess/deficit volumes and uneven spots at a glance. If the heat map is displayed in AR through the smartphone, the color distribution can be overlaid directly on the actual ground or structure for confirmation. This enables detection of subtle elevation differences and proactive quality control such as correcting areas likely to require rework. In practice, sites that have implemented this technology have reported cases where small excess embankment discovered via the heat map was immediately cut back, preventing later rework.

Because point cloud data provides dense, objective information, it yields more reliable as-built records than paper-based spot measurements. Furthermore, this 3D measurement method is an officially recognized measurement method in accordance with the Ministry of Land, Infrastructure, Transport and Tourism’s “As-built Management Guidelines.” The acquired coordinates are managed in public coordinate systems (plane rectangular coordinate system) and can be output after immediate conversion to any desired coordinate values such as the Japan Geodetic Datum (JGD2011/2024) as needed. Therefore, the created as-built drawings and quantity data can be used directly as materials for inspection submission and handled in formats suitable for electronic delivery. Also, because soil volumes for embankment and excavation can be easily calculated from the obtained point cloud, this helps not only with as-built management but also with tracking progress (quantity of work performed). In other words, with a single smartphone, you can seamlessly obtain and use everything from on-site quality control to measurement results for administrative submission. Digitalizing and streamlining as-built management is a critically important theme in on-site DX, and smartphone surveying can significantly lower that barrier.

Real-time information collaboration through cloud sharing

Surveying and as-built data collected with a smartphone can be shared to the cloud in real time. In LRTK, positioning data, point clouds, and site photos are uploaded instantly to the cloud, allowing immediate sharing of information with office staff and stakeholders at remote locations. Data that previously had to be brought back on USB drives or paper is kept up to date on the cloud, enabling timely communication between the site and the office without delays.

For example, if the pile head coordinates are recorded on a smartphone immediately after piling, a manager in the office can check that pile position via the cloud and instantly verify there are no discrepancies. Point cloud data for as-built conditions is displayed in 3D in a browser shortly after upload, so construction managers can view heat maps on their office PCs and issue corrective instructions to the site as necessary. By sending a sharing URL to clients or subcontractors who do not have specialized software, anyone can view the current 3D data in a web browser, simplifying inspections and reporting. Because the cloud also allows direct viewing of point clouds and measurement of distances and areas, persons other than the responsible staff can utilize the data, greatly expanding opportunities for information use.

Data shared in real time forms the foundation for all stakeholders to make decisions and hold discussions based on the same latest information. From site foremen to designers and clients, everyone can check as-built and surveying results on a single cloud platform, reducing rework and communication loss caused by differences in understanding. Ultimately this contributes to shorter construction periods and fewer quality issues, thereby improving project-wide productivity and reducing costs. On-site DX leveraging the cloud and smartphones is poised to become the standard.

How will sites change by introducing smartphone piling?

Sites that have actually introduced smartphone surveying have seen clear improvements in efficiency and accuracy. At a certain road improvement project, a piling staking operation that previously required a three-person team and half a day was completed by one person in about two hours using a single smartphone. As-built inspections also benefited: tasks that traditionally took several days from measurement to drafting were processed on the same day by using point cloud scans, allowing reports to stakeholders to be submitted that same day. Site managers have commented that “waiting time for surveying has decreased, and the construction cycle has become significantly smoother.”

At another bridge foundation project, all pile positions and elevations were measured and shared to the cloud immediately after piling was completed, enabling deviations to be identified and corrected within the same day. Comments included that “previously we had to wait for surveying results and correct things the next day or later, but being able to confirm on the spot provides peace of mind.” The benefits that smartphone-based piling and as-built management bring to the site are often noticeable from the first day of introduction. Common outcomes across sites include reduced waiting time and rework for surveying, with positive effects on both productivity and quality control. Because the tools are intuitive for younger staff as well, the period required to acquire skills has shortened. Reports indicate that surveying personnel now have more bandwidth to focus on other management tasks.

Eliminating dependence on individuals and promoting DX by introducing high-precision smartphone surveying

As described above, adopting a system that handles everything from piling to as-built management with a single smartphone addresses many on-site issues. Digital technology provides accurate coordinates and data without relying on special surveying equipment or advanced skills, allowing less experienced workers to be entrusted with important surveying tasks with confidence. This directly resolves dependence on specific individuals and helps maintain stable construction quality despite labor shortages.

Moreover, the barrier to introducing high-precision smartphone surveying is very low. By installing the dedicated app “LRTK” on a supported iPhone and signing up for the service, you can obtain a centimeter-level positioning environment that previously required expensive dedicated equipment. The portability—being easy to carry to the site and always ready to be taken out of a pocket for surveying and recording—provides convenience unimaginable with traditional equipment. LRTK is designed as a tool for the field to be carried “one per person,” always available when needed, making it truly a pocket-sized all-purpose surveying instrument. The app automatically measures distances between survey points, performs coordinate transformations, and records notes, eliminating the need to keep field notebooks. It is advisable to begin smartphone surveying with trial small-scale surveying tasks to experience its benefits firsthand.

Within the flow of i-Construction and ICT construction promoted by the Ministry of Land, Infrastructure, Transport and Tourism, adopting smartphone surveying as part of on-site DX is a compelling option. Companies and municipalities adopting solutions like LRTK are increasing, and the sophistication of construction management using high-precision positioning is progressing. Small- to medium-sized contractors and surveying businesses have also begun to introduce these tools, which are attracting attention as easily adoptable DX tools. The main benefits of introducing smartphone surveying can be summarized as follows:

• Reduction of surveying manpower (pile staking and as-built measurement by fewer people in shorter time)

• Improvement of construction accuracy (positioning and inspection with millimeter-level accuracy to reduce quality defects)

• Smooth information transfer through real-time sharing (immediate sharing of on-site status via the cloud)

• Enhanced quality records (visualize and quantitatively evaluate as-built conditions with point cloud data and preserve reliable evidence)

• Reduced reliance on skilled personnel (digital tools enable anyone to manage accuracy and help standardize skill transfer)

• Improved work safety (surveying from a distance with fewer personnel reduces risks in hazardous areas)

• Cost reduction (efficiency gains and fewer mistakes reduce labor and rework costs)

It is not an overstatement to say that the world of piling and surveying is about to change dramatically with the introduction of a single smartphone. Construction managers should consider taking this opportunity to take the first step in DX with high-precision surveying that can be started with just a smartphone. By digitalizing the entire workflow from piling to as-built management, site productivity and quality will improve dramatically, and you can quickly realize a new construction style that may become the standard in the future. Pick up a smartphone and experience the future of construction management.