Revolutionizing Traditional Piling Work! High-Precision Smartphone Surveying Makes Layout Positioning from Drawings Easy for Anyone

Pile-driving work performed at construction sites (pile-driving work (setting out positions according to design drawings and installing piles)) is an extremely important process that affects the accuracy and quality of structures. However, conventional pile layout setting-out has been time-consuming and labor-intensive, and has faced the problem of having to rely on experienced specialists. Now, by leveraging smartphones and the high-precision positioning technology "LRTK", a new era has arrived in which anyone can easily set out positions according to the drawings. This article explains in detail the problems of conventional pile-driving work and the innovation of high-precision smartphone surveying that solves them. Let’s look at the benefits of the latest technology that dramatically reduces workload and significantly improves accuracy.

Challenges in Conventional Piling Operations

Traditional stake setting (pile driving) layout work relied mainly on surveying instruments and manual labor. Distances were measured from reference points on drawings with a tape measure, marks were made on the ground, and stakes were driven — with such methods various issues arise concerning ensuring accuracy and work efficiency. The main problems can be summarized as follows.

• 複雑な測量手順と多くの人手: Staking out pile positions typically required two or more personnel: a tripod-mounted operator handling surveying instruments such as a transit or auto level, and assistants marking positions with a staff rod and a measuring tape. The procedures were complicated, and it took considerable time to establish each point.

• 専門知識と熟練を要する作業: Operating surveying instruments and deriving distances from drawings required experience, so reliance on skilled surveyors was unavoidable. New or less experienced workers alone found it difficult to set out accurate positions, and there were issues with a shortage of technicians and generational turnover.

• 視通の確保など現場環境への制約: Staking out with a total station (optical surveying) assumes an unobstructed line of sight between the instrument and the target. At sites with complex terrain or structures, or during nighttime work, visual guidance is limited, and conventional methods can be difficult to apply.

• ヒューマンエラーのリスク: Mistakes such as misreading a measuring tape or marking incorrectly—human errors—were a major challenge. If pile positions were wrong, later stages would require rework because "the positions don't match," causing schedule delays and additional costs. Even a deviation of only a few centimeters (a few in) can affect the safety of the entire building, so ensuring the accuracy of staking out pile positions was extremely important.

As described above, conventional pile-driving layout work had room for improvement in both accuracy and efficiency. For that reason, dedicated equipment aimed at reducing labor and mistakes has been developed, but high-performance total stations and automatic pile-driving navigation systems are expensive and take time to learn to operate, making them difficult to introduce at small- and medium-sized sites and for beginners. "Isn't there a way to make it easier so anyone can accurately set out pile positions?" — such voices from the field called for technologies to meet that need.

Innovation in Drawing-Coordinate Navigation Using Smartphones × LRTK

In recent years, thanks to improvements in smartphone performance and advances in positioning technology, high-precision surveying using only a smartphone has become increasingly possible. The key to this is a positioning method called RTK (Real Time Kinematic). RTK corrects the errors in position information obtained from GNSS (Global Navigation Satellite System) in real time, allowing the current position to be pinpointed with astonishing accuracy within an error of a few centimeters (a few in). Traditionally, dedicated antennas, high-performance receivers, radio equipment, and other specialized devices were required, but recently compact devices that integrate these have appeared. LRTK is one of them: an all-in-one RTK-GNSS receiver that can be attached to and used with a smartphone.

A small LRTK device that attaches to a smartphone. It is pocket-sized, weighing approximately 165 g, and has a built-in antenna and battery; simply attaching this device transforms a smartphone into a surveying instrument with centimeter-level accuracy (half-inch accuracy). Compared with conventional stationary surveying equipment, it is dramatically lighter and more compact, making it easier to carry and operate in the field.

Smartphone Quickly Transforms into a High-Precision Surveying Instrument

When you attach the LRTK device to your smartphone and launch the dedicated app, the smartphone itself becomes a high-precision GNSS surveying instrument. The smartphone screen displays preloaded design plan coordinate data (latitude and longitude or planar coordinates of where stakes should be placed), and you can check deviations from your current position in real time. For example, you can align yourself by looking at the digitally displayed distance and direction such as "0.05 m (0.16 ft) east and 0.10 m (0.33 ft) north to the target point." This greatly reduces the hassle of repeatedly remeasuring with a tape measure while holding drawings in one hand, or going back and forth between reference stakes and target stakes to fine-tune positions, as was traditionally done. Imagine the smartphone automatically navigating you to the stake location. Because you don't have to rely on human estimation or calculations, surveying errors are dramatically reduced, and consistently accurate positioning can be expected.

Coordinate navigation feature guides anyone accurately without getting lost

The true strength of a smartphone + LRTK lies in its coordinate-guidance (navigation) function, which allows even beginners to reach their target point accurately without getting lost. Usage is simple: just select the target coordinate point set beforehand in the cloud or in the app and press "Start guidance." On the smartphone's screen, the direction and remaining distance to that point are constantly displayed, guiding the worker to the destination much like a car navigation system. As you approach the target, the distance display decreases, and when it is nearly zero you have arrived at the position specified by the design coordinates. Finally, you just mark the spot and drive the stake in. With this, even without complex surveying knowledge, you can find the exact stake-driving position simply by following the on-screen directions.

A dedicated smartphone app guiding users to the pile-driving position. The screen prominently displays the direction to the destination (arrow) and the remaining distance, allowing anyone to intuitively identify the target point. As you approach the destination, the display gradually approaches 0, making it immediately clear when the target coordinates are exactly matched. Because the digital navigation always guides you to the correct position in this way, even non-experts can indicate the points specified on the drawings without hesitation.

Using the coordinate navigation feature, stake-out work that used to require several people can be completed by a single person. There is no need to carry and set up heavy tripods or surveying instruments; you simply walk to the target location with a smartphone in hand. This achieves significant labor savings and helps alleviate personnel shortages. Also, because workers can see in real time the discrepancy between their position and the target position, they no longer have to worry "Is this really correct?", allowing them to approach driving stakes with confidence. Even if experienced veteran technicians are not on site, workers can perform tasks without mistakes by following the guidance on their smartphones, which broadens staffing options.

Intuitively visualize locations with AR display

As a reassuring feature of smartphone guidance, visual guidance via AR (augmented reality) display can also be cited. By showing the site through the smartphone camera and overlaying virtual arrows or markers on the screen, it can visibly indicate on the spot where piles should be driven. AR displays based on high-precision positioning data have almost no positional offset, displaying points on the design drawings as if they were pinned to the actual ground. Workers only need to walk in the direction the arrow on the camera screen points, so they don’t have to rely on spatial intuition or imagination. Thanks to the intuitive guidance, even those unfamiliar with surveying can reach the exact location as if following a game marker.

AR-based visual support also prevents situations that used to occur frequently, such as "losing sight of measurement points" and "not knowing which mark is which". Instructions superimposed on the real-world view are very easy to understand, help workers' spatial awareness, and are expected to reduce marking mistakes and rework. By using digital technology to "visualize", tasks that once relied on intuition and experience are being transformed into standardized procedures that anyone can perform.

Easy recording and sharing with the geotagged photo feature

Stakeout surveying using a smartphone and LRTK not only guides positioning but also contributes to streamlining record-keeping. The dedicated app has a feature called Geotagged Photos, and when you take a photo with your smartphone at the location where a stake was set, that photo is automatically linked with the precise coordinates of the shooting location and the camera orientation. In other words, every photo—showing where and in which direction it was taken—is saved as data with cm level accuracy (half-inch accuracy) position information. The shooting date and time and any notes are also recorded at the same time, so you won't have to wonder later, "Where was this photo taken?"

Recorded photo data can be uploaded to the cloud in real time and shared instantly with staff in the office. For example, if you take a photo on site immediately after driving a pile, headquarters and supervisors can view the pile’s installation location and the photo on a web-based map at that moment. There is no need to jot down positions by hand on paper drawings or to sort photos later and compile them into reports. Digital integration smooths information sharing between the field and the office, reducing reporting time and helping prevent recording errors.

Also, photos with location information can be used for post-construction as-built records (the shape of the completed structure) and for maintenance management. Not limited to pile driving, if you photograph locations noticed during inspections, you can accurately record their positions and track them in the future. Smartphone surveying with LRTK streamlines the whole process, taking it beyond 'measure and be done' to 'measure, record, and make use of'.

Supports 3D point cloud measurement to capture the entire site

The benefits of high-precision surveying with smartphones are not limited to planar positioning. The combination of LRTK and smartphones also makes it possible to perform 3D point cloud measurements using LiDAR (light detection sensors) built into iPhones and iPads. Point cloud measurement is a technique that acquires the shape of a site as a large collection of measurement points (a cloud of points = point cloud), and has been attracting attention in recent years as the kind of data produced by laser scanners and drone surveying. Using LRTK gives precise positional coordinates to point cloud data measured with a smartphone, so even simple 3D scans can record the entire space with accurate dimensions.

For example, if you scan the foundation and ground conditions of a construction site with a smartphone and generate point clouds, this can help with as-built verification and calculation of fill and cut volumes. 3D measurement, which previously required specialized equipment, is now possible with a single palm-sized device. The acquired point clouds can be shared via the cloud, making it easy for stakeholders to view and utilize the measurement results on PCs and tablets. Such 3D capabilities enable end-to-end digitalization and DX—from staking out pile positions through construction management to inspection and record-keeping—and contribute to improved on-site productivity.

Expected Effects from Implementation and Future Outlook

The new stake-out surveying method using smartphones and LRTK offers very significant benefits on-site. Here, let’s once again summarize the main effects.

• Dramatic improvement in surveying accuracy: With RTK centimeter-level positioning (half-inch accuracy) and digital guidance, stakes can always be placed at the exact locations shown on drawings. Human error is drastically reduced, directly leading to more stable and improved construction quality.

• Significant reduction in work time: Because one person can efficiently set out positions, work time can be greatly reduced compared to conventional methods. In some cases, it has been reported that surveying work was completed in about 1/6 of the time previously required, dramatically increasing the number of pile-driving locations that can be handled in a single day.

• Labor savings and response to labor shortages: Because tasks can be carried out with a small crew, labor costs can be reduced, and even when experienced workers are lacking, anyone can become an immediate asset and participate in surveying work. Training costs for newcomers are also greatly reduced because operation is simple—just follow the on-screen guidance.

• Improved safety and reduced workload: Reducing the number of workers around heavy machinery lowers the risk of contact accidents, and shortening long surveying tasks in the heat can reduce the risk of heatstroke. By making the work itself more efficient, the burden in areas with poor footing is also reduced, contributing to a safer site environment.

• Enhanced quality control through data utilization: Because positioning data, photos, and point clouds are shared in the cloud immediately, construction managers can grasp the situation in real time and issue instructions. Digitizing records prevents missed reports and communication errors, helping to prevent problems before they occur and enabling rapid response.

In this way, the innovation in pile-driving work enabled by high-precision surveying with smartphones delivers results that surpass conventional methods in every aspect—accuracy, efficiency, safety, and record management. The momentum of "i-Construction (Ai-Construction)" promoted by the Ministry of Land, Infrastructure, Transport and Tourism also provides a tailwind, and construction DX leveraging GNSS and AR is likely to expand even further. Tasks that used to rely on the intuition and skill of veteran workers are increasingly shifting to smart construction that anyone can perform through the power of digital technologies.

Summary: Toward an Era of High-Precision Stakeout Surveying Accessible to Everyone

The task of marking pile-driving positions, which once required experience and effort, has begun to transform into an easy operation that anyone can perform thanks to smartphones and LRTK, becoming a simple task anyone can handle. Centimeter-level positioning (cm level accuracy (half-inch accuracy)) and intuitive coordinate navigation enable advanced surveying with "All you need is a smartphone". Sites that have long suffered from traditional inefficiencies and mistakes stand to benefit the most from this technological innovation. Smartphone surveying solutions—offering many advantages such as reduced work time, relief from labor shortages, ensured quality, and improved safety—are rapidly becoming the new standard on job sites.

Why not bring to your site the revolution in traditional pile-driving work: high-precision pile-driving surveying with a smartphone + LRTK? By making cutting-edge technology your ally, an era has arrived in which anyone can easily and reliably stake out drawing positions. On future construction sites, it will be possible to achieve the same level of accuracy as skilled craftsmen with a single smartphone, enabling efficient, error-free construction. Be sure to check the [LRTK official site](https://www.lrtk.lefixea.com/). By adopting new technology, you can dramatically raise productivity and quality and pioneer the future of pile-driving work.