Solo pile-driving guidance techniques: Labor-saving surveying and safety improvements with AR piles + high-precision GNSS

Table of Contents

• Challenges in pile-driving work

• How GNSS and AR change pile-driving guidance

• Labor savings in surveying by solo work

• Safety improvements with AR pile guidance

• Simple surveying with LRTK

• FAQ

Pile-driving work on construction sites is a critical process that requires placing piles at precise positions determined from reference points. This operation affects construction quality, but worksites face chronic labor shortages and increasing needs for safety assurance, so methods that enable more labor-efficient and safer work are in demand. Traditionally, pile-positioning relied on manual work by multiple people; recently, an innovative approach combining GNSS (high-precision satellite positioning) and AR (augmented reality) technologies has emerged. This new approach enables a single person to perform pile positioning and guidance, greatly reducing surveying effort while improving safety. This article explains this "solo pile-driving guidance" method, covering traditional challenges, how the new technologies work, and the benefits in terms of labor savings and enhanced safety.

Challenges in pile-driving work

In civil engineering, "driving piles at accurate positions" is the most important point affecting construction quality. However, conventional pile-driving (positioning) work has many inefficiencies. Typically, a surveyor and an assistant form a two-person team to set up surveying instruments like total stations and derive pile positions on site from plan coordinates. Tasks include measuring distances with tapes from reference points and marking the ground, or moving people around while sending signals by radio or hand signs—so even setting a single pile required cumbersome procedures. Therefore, on large sites with many piles, surveying and pile-positioning work alone could sometimes take more than a full day.

Manual surveying also carries the risk of human error. Miscommunication between the surveyor and the operator can cause position offsets, and misreading or incorrect recording of coordinates can lead to incorrect pile placement. That in turn may require re-driving piles or rework in subsequent processes. In addition, on steep slopes or near water where footing is poor, marking or placing pile indicators can be difficult in the first place. In recent years, some large sites have started introducing machine guidance systems that equip heavy machinery with GNSS, but because of the high cost of specialized equipment, they have not yet spread to small- and medium-scale projects. In fact, reports indicate that conventional optical surveying for pile layout took about six times longer than methods using the latest digital technologies. Against this backdrop, a more efficient and accurate method of pile-driving guidance has long been sought.

How GNSS and AR change pile-driving guidance

The key to solving these issues is the use of high-precision GNSS positioning and AR displays. Among GNSS methods, RTK (Real Time Kinematic) positioning can identify a current position with errors of only a few centimeters. Simply put, it is an "ultra-high-precision GPS usable on site"; while inexpensive handheld GNSS devices used to have position errors of 5–10 m (16.4–32.8 ft), RTK provides precision sufficient for construction use. In the Ministry of Land, Infrastructure, Transport and Tourism's "i-Construction (ICT construction)," utilizing GNSS for labor savings and advancement of construction is a key theme, and RTK-based pile-guidance is a prime example of such cutting-edge technology.

Recently, an approach called "smartphone surveying" has emerged that makes RTK positioning easily accessible by combining a smartphone with a compact high-precision GNSS receiver. Without large dedicated equipment, attaching a GNSS unit weighing a few hundred grams to a single smartphone enables centimeter-level (half-inch accuracy) positioning. This allows each field staff member to carry a high-precision positioning terminal and perform surveying whenever needed. For example, if pile coordinate data from construction drawings are preloaded into an app, the screen can display in real time the remaining distance and direction like "5 cm east, 10 cm north" to the target point, and the operator can reach the precise position with just a few steps following those instructions. Tasks that previously required several people to stretch a tape measure can now be completed solo with a smartphone in hand.

Furthermore, AR technology can overlay markers for pile-driving points or virtual piles onto the real-time camera view on the smartphone. Because the camera screen visually indicates "drive the pile here," even those without advanced surveying skills can follow intuitive guidance to place piles accurately. This greatly reduces mispointing and re-drives, and reduces variations in work accuracy. In sites that have implemented such systems, reports indicate dramatic reductions in the time required for pile layout and almost no position-correction rework in subsequent processes. By combining high-precision coordinate navigation via GNSS with visual guidance from AR, digital guidance is enabling pile-driving work to be performed efficiently and accurately by a single person.

Labor savings in surveying by solo work

Enabling a single person to perform pile-positioning dramatically improves on-site productivity. Below are the key points of labor savings achieved by GNSS × AR.

• Personnel reduction: Pile layout that formerly required a surveyor and laborer team can be handled by one operator, greatly reducing staffing needs. Even with limited personnel, workers can complete pile layout without waiting for a surveying team, helping to alleviate labor shortages.

• Shorter work time: High-precision GNSS navigation guides operators to target points without wasted movement, significantly shortening positioning time. In some cases, pile positioning that used to take half a day can be completed in about an hour. In a comparative experiment, pile layout using GNSS and AR reportedly took about one-sixth of the time required by conventional optical methods, demonstrating a very large efficiency impact. Additionally, GNSS surveying allows a single antenna to be carried while walking to points even on sites with elevation differences or obstacles, eliminating the need to repeatedly set up equipment and enabling continuous and smooth surveying.

• Reduced mistakes and rework: Digital coordinate guidance reduces human measurement and communication errors. If piles are placed accurately from the start, unnecessary re-measurement or re-driving is reduced, preventing rework in later processes. This leads to shorter construction periods and reduced costs.

• Skill leveling: Following GNSS guidance and AR prompts, anyone can place piles with the same accuracy without relying on the intuition or experience of veterans. Workers without advanced surveying knowledge can use the system intuitively, stabilizing work quality regardless of operator skill level. This is a major benefit for maintaining site quality amid a shortage of skilled technicians.

As described above, pile-guidance technology that enables solo work yields not only labor savings but also quality improvements. Waiting times for surveying are reduced, allowing other tasks to proceed without interruption and improving overall site productivity.

Until now, arranging a surveying team for positioning often required temporarily halting other work, creating inefficiencies in scheduling. With solo surveying, operators can identify pile positions themselves when needed, eliminating wait times and keeping construction on schedule. Introducing such labor-saving technologies thus contributes significantly to shorter construction periods and improved productivity overall.

Safety improvements with AR pile guidance

Making pile-guidance completable by a single person also brings major safety benefits. Traditionally, during pile-driving, a guide would stand near the heavy machinery and send signals by hand or radio; having people close to heavy equipment carries obvious risks. By digitizing guidance so the operator can perform it themselves, there is no need to station guides in hazardous areas.

AR pile-position displays also make it possible to determine positions safely in places where workers cannot physically approach. For example, in pile work on steep slopes, operators have used procedures in which they indicate the target position by placing a virtual pile in the smartphone view from a safe distance and then excavate directly beneath that indicated spot to drive the pile. Even on poor footing, accurate positions can be determined without forcing personnel into dangerous areas, helping to prevent falls and reduce occupational accident risks.

Thus, solo-completable pile-guidance has the effect of "not having people stand in the work area," which ultimately enhances site-wide safety. With fewer personnel waiting nearby to guide, the risk of contact accidents during machine operation decreases. Heavy equipment operators also feel safer and experience reduced mental burden when no guide is standing nearby. The ability to realize both labor savings and improved safety is another major attraction of GNSS × AR pile-guidance technology.

Simple surveying with LRTK

Finally, as a solution that makes solo surveying using GNSS × AR easy to realize, we introduce our smartphone RTK system "LRTK." LRTK consists of a small high-precision GNSS receiver that attaches to a smartphone and a dedicated app, functioning as a pocket-sized surveying instrument anyone can carry. It positions the current location with centimeter-level (half-inch accuracy) precision and navigates to pre-registered pile coordinates, so even without specialized surveying equipment, one person can perform accurate pile layout.

The LRTK app screen displays a target marker indicating the direction and distance to the target coordinate; as you approach the target, a cross-shaped virtual pile mark appears on the camera image to intuitively show "drive the pile here." The app also notifies users with sound or vibration when approaching the target so they can confirm arrival while checking surroundings for safety. Even first-time users can identify the target point by following visual guidance. Position data for each measured point and photos taken on site are automatically recorded to the cloud, allowing accurate review of "when, where, and what was done" later. Daily reports and as-built documentation can be completed with a single tap, and digitizing surveying records streamlines reporting tasks.

LRTK also supports 3D scanning (photogrammetry) using iPhone or iPad LiDAR and cameras. After pile-driving, the same device can measure as-built conditions as point cloud data and immediately compare that data with the design model. Because the acquired point cloud already includes positioning coordinates, comparisons and deviation detection with design data can be performed without separate georeferencing. For example, scanning the construction area after pile completion lets you verify on the spot whether pile placements match the design and apply the data to volume calculations. Performing positioning before pile-driving and inspection/recording after work in one seamless system is a major strength of LRTK.

Moreover, compared to conventional high-precision GNSS equipment that used to cost millions of yen, smartphone surveying systems like LRTK can be introduced at very low cost. The compact, lightweight receiver attaches to existing smartphones, so there is little need to learn new dedicated terminals. The ease of operating on familiar smartphone screens makes one-device-per-person deployment realistic.

Using LRTK, the efficiency and accuracy of pile-positioning are beginning to improve dramatically. For example, cases have been reported in which pile-positioning that used to take half a day was completed in about one hour with smartphone RTK guidance. Comparative experiments also showed that GNSS × AR pile layout required roughly one-sixth the time of optical surveying methods, achieving striking labor savings. Furthermore, if a communication environment is available, correction information can be obtained in real time to enable positioning anywhere nationwide, so compact LRTK proved powerful even in disaster recovery sites where large equipment could not be brought in. Introducing inexpensive, portable smartphone GNSS systems to sites is making it possible to perform high-precision pile-guidance regardless of scale or situation. LRTK thus represents a strong solution to issues such as labor shortages and on-site safety assurance.

Going forward, wider adoption of high-speed communications like 5G and further use of AR glasses may enable even more precise, real-time guidance and hands-free work. As ICT construction advances, this solo pile-guidance style is expected to become a new on-site standard. By engaging with advanced technologies and gaining practical experience now, firms will be able to adapt smoothly to future technological developments.

FAQ

Q. How accurate is high-precision GNSS positioning? A. With RTK-style high-precision GNSS, horizontal positioning accuracy is on the order of a few centimeters. Generally, accuracy of ±2–3 cm (±0.8–1.2 in) is cited, which is sufficient for pile-positioning. However, when millimeter-level accuracy is required (for example, in establishing reference points or finish control of structures), using optical surveying instruments such as total stations in combination is recommended.

Q. Can GNSS positioning be used stably in any environment? A. GNSS performs best in environments with a clear view of the sky. Positioning can become unstable or less accurate inside tunnels, in areas surrounded by tall buildings, or in dense forests where satellite signals are obstructed. Extremely severe weather such as heavy rain may slightly degrade accuracy, but normal rainy conditions are usually not a major problem. In environments where GNSS is difficult to use, it is advisable to combine GNSS with other surveying methods such as total stations as appropriate.

Q. Can it be operated without specialized surveying knowledge? A. Yes, it can be operated relatively easily. The smartphone screen displays the current position and arrows/distances to the target point, and AR markers in the camera view provide guidance, so intuitive positioning is possible without complex surveying calculations or veteran intuition. Simple training on device setup and how to import coordinate data is recommended for first-time users, but once mastered, the system is designed so field workers themselves—not necessarily skilled surveyors—can operate it.

Q. Is the introduction cost high? A. Compared to conventional total stations or machine guidance systems installed on heavy equipment, smartphone-compatible GNSS surveying systems have much lower barriers to introduction. Initial investment is required for high-precision GNSS receivers and dedicated apps, but considering labor cost reductions and shortened construction schedules, the cost performance is sufficiently high. In addition, enabling each worker to perform surveying in-house creates added value by reducing reliance on outsourcing or specialized teams. National and local governments also provide support for spreading high-precision GNSS equipment as part of ICT construction initiatives, and subsidy programs may be available. It is advisable to consider phased introduction according to your company’s construction needs.

Q. Is it necessary to install a dedicated base station? A. No. In many cases, high-precision positioning is possible without placing a dedicated base station on site. RTK positioning requires correction data, but in Japan there are established methods such as obtaining correction data via the Internet from the Geospatial Information Authority of Japan’s permanent GNSS stations or using the quasi-zenith satellite system "Michibiki" centimeter-class augmentation service (CLAS). Modern smartphone RTK systems, including LRTK, utilize these mechanisms, and with a communication connection, centimeter-level positioning can be achieved without a dedicated base station. However, in communication-deprived mountainous areas, real-time positioning may become unstable, so operational planning according to conditions is necessary.

Q. What precautions should be taken when using the system? A. When using AR pile-guidance, safety should come first. Focusing too much on the smartphone screen can cause you to miss obstacles underfoot, so move slowly while checking your surroundings. When you approach the target point, stop and visually confirm the actual terrain and any obstacles to be safe. To fully realize high-precision GNSS performance, use the antenna in open sky conditions and check device battery level and communication status beforehand. AR guidance is highly useful but should be treated as an aid; always verify site conditions with your own eyes while using the system.