Driving piles that support columns and foundations at construction sites is a critical process that affects the safety of structures. However, the work of guiding pile placement has traditionally relied heavily on experience and intuition, making it difficult for beginners. On site, positions must be calculated from drawings, marked on the ground, and piles driven at those marks, but this procedure is time-consuming, labor-intensive, and prone to mistakes.

In recent years, the construction industry has accelerated the use of digital technologies such as ICT and AR to improve construction efficiency (so-called Construction DX). Within this trend, a new approach to pile-driving guidance has emerged. To ensure you “won’t get lost when driving piles,” a system was needed that enables anyone to easily and accurately identify pile positions. Enter the pile-driving navigation using an AR guidance app that combines a smartphone with high-precision GNSS. This article explains this innovative method and the “LRTK” app that makes it possible. With this new approach, pile-driving work will become far more efficient, allowing anyone to carry out accurate work without getting lost.

Table of contents

• Challenges of pile-driving guidance in foundation and temporary works

• Visualizing pile positions with AR display and coordinate navigation

• Workflow for pile-driving guidance using LRTK

• Frequently asked questions

Challenges of pile-driving guidance in foundation and temporary works

“Pile driving” is the process of driving piles into the ground to support buildings or civil engineering structures, and it is mainly carried out as part of foundation work. When the ground’s bearing capacity is insufficient, concrete or steel piles are driven deep into the ground to transfer loads to a stronger bearing layer and reinforce the foundation. Pile work includes methods such as installing factory-made piles (precast pile method) or excavating on site and pouring concrete (bored pile method), but in any method it is important to construct at the designed positions and depths. Temporary works also sometimes require sheet piles or temporary piles for earth retention. For example, in excavations with significant depth, steel sheet piles may be driven to form a temporary retaining wall, but if the positions or spacing of those sheet piles are off, they will not be effective. Even for temporary structures, accurate pile installation is required.

In all cases, the accuracy of pile positions according to the drawings directly affects the quality and safety of subsequent work. If the pile center is off, the superstructure may deform or the planned bearing capacity may not be achieved. Therefore, guidance for pile-driving positions demands extremely high precision. Because even small errors can affect the safety of an entire building, careful verification is performed before pile driving.

However, traditional pile-driving guidance has been centered on manual work and has required significant labor and experience. The common method is to read coordinates and dimensions of pile positions from design drawings, measure distances from site benchmarks with tapes or surveying instruments, and mark the ground. On large sites, temporary reference frames called “chouhari,” using wooden stakes and mason’s lines, may be set up and positions referenced from those. But in urban small sites or sites with complex structures, there often isn’t enough space to set up chouhari. In underground levels or sites with many obstructions, poor sightlines increase the work needed to re-establish survey points.

Also, human errors are unavoidable with traditional surveying methods. Mistakes such as misreading a tape measure, copying calculation values incorrectly, or marks being erased by passing machinery commonly occur on site. Even small errors in pile position can require extra excavation or repair later, leading to schedule delays and increased costs. For this reason, many sites have survey personnel double-checking before pile driving, and construction managers carefully verify markings. Still, under complex site conditions it is difficult to eliminate human error completely, and the persistent question has been “how can we make pile-driving guidance more accurate and efficient?”

Against this backdrop, dedicated devices to streamline pile position setting have appeared in recent years. Examples include single-operator systems using a total station (TS) and prism, and layout navigator devices for pile driving provided by various manufacturers. While TS can perform high-precision surveying, it requires sufficient lines of sight and reference alignment to set up on site, and measurements often need to be redone as underground spaces or structures increase. TS surveys are usually performed by a two-person team (operator and prism holder), making it difficult and unsafe to allocate personnel in cramped excavation pits or at heights, and posing challenges for small crews. Dedicated devices can reduce surveying labor, but the equipment itself is often expensive and may require time to master. Especially on small- to medium-scale jobs or sites lacking surveying specialists, adoption hurdles remain high.

“Can we guide pile-driving positions more easily so anyone can do it accurately?” Responding to this need, attention is focused on a new approach using a smartphone and an app to guide pile driving. By combining the familiarity of smartphones with the latest technologies, attempts have begun to dramatically streamline on-site position-setting work.

Visualizing pile positions with AR display and coordinate navigation

The trump card for solving conventional challenges is pile-driving guidance that utilizes AR display and high-precision coordinate navigation. This is realized by a compact GNSS device that attaches to a smartphone and a dedicated app. The key technology is RTK high-precision GNSS positioning. RTK (Real Time Kinematic) is a positioning technique that corrects satellite positioning errors in real time to determine positions with centimeter-level accuracy (half-inch accuracy). Previously, expensive GNSS receivers and radio equipment were required, but LRTK integrates these into a palm-sized, all-in-one device that can be attached to a smartphone. The device itself weighs approximately 200g, is lightweight, and houses a high-performance antenna, battery, and communication module in a rugged design suitable for field use. Simply attaching it to a smartphone turns an everyday smartphone into a high-precision surveying instrument. The LRTK device also includes inclination correction, so even when a survey pole cannot be held perfectly vertical, the tip position is automatically corrected to obtain accurate coordinates. This helps maintain accuracy even when a pole cannot be stood straight due to obstructions, making it useful in narrow sites or terrain with elevation differences.

The LRTK app offers various features to support on-site position setting, of which the AR guidance display is particularly notable. Based on coordinate data of pile positions registered in the cloud or app in advance, virtual markers and arrow navigation are overlaid on the smartphone camera view. For example, if you select the coordinates of the pile position to be driven and tap “Start Navigation,” the screen will show distance information such as “X m to target” and an arrow indicating the direction to move, updated in real time. The worker simply holds the smartphone and walks in the direction the arrow points to approach the target point. As the distance approaches zero, the discrepancy between the current position and the target coordinates is virtually eliminated, and the worker can stand on the pile center with an error of within a few centimeters (within a few inches). The fact that accurate position setting can be achieved by just “following the on-screen guidance,” without complicated surveying calculations or specialist knowledge, is revolutionary.

Workflow for pile-driving guidance using LRTK

• Preparing pile position data: Extract the coordinates of the pile installation positions from the construction drawings. From reference lines and design values on the drawings, calculate latitude/longitude or planar coordinate values and compile them in Excel or CSV format.

• Importing data into the app: Import the prepared coordinate data into the LRTK cloud or smartphone app. Multiple points can be registered in bulk and made available for immediate retrieval on site.

• Attaching the device on site and starting navigation: Attach the LRTK device to the surveying smartphone and launch the app. Select the pile point to guide from the list and tap “Start Navigation” to begin. The app starts guidance once it receives GNSS correction data and high-precision positioning is available.

• Guiding to the target point and driving the pile: Follow the AR display on the smartphone screen to move to the target point. When you arrive at the indicated position, mark it and drive the pile with the pile driver. If there are additional piles, select the next point and continue sequential guidance.

Using AR features, pile positions can be visualized even in places where physical marking is difficult. For example, on floors covered with concrete where marking is hard, or on steep slopes that are dangerous to access, a virtual pile can be displayed on the smartphone screen to indicate the location. This allows workers to identify distant points visually from safe areas, eliminating the need to enter hazardous locations. It also enables accurate pointing to areas where people cannot approach due to machinery operation, thereby improving construction safety.

For instance, in slope reinforcement work on steep terrain, you can virtually place an AR pile from a safe upper location on the smartphone, determine the position directly below it for excavation, and then confirm the pile-driving location. Traditionally, workers would need to descend dangerous slopes to snap lines, but AR guidance makes it possible to remotely and safely indicate precise positions.

Introducing this smartphone × GNSS × AR pile-guidance system on site yields many benefits:

• Dramatic improvement in work efficiency: Position-setting work that used to require two people and half a day can be completed quickly by one person using LRTK navigation. Because multiple points can be guided while moving, the number of piles that can be processed in a day increases significantly, shortening the overall schedule. In a comparative experiment, introducing RTK and AR for pile guidance reportedly reduced the time required for position guidance to about 1/6 compared with traditional optical surveying layout work.

• Improved surveying accuracy and reduced errors: In addition to RTK’s high-precision positioning, AR visual guidance reduces human reading and communication errors. Guiding the pile driver or workers according to on-screen instructions enables installation at design coordinates and dramatically reduces rework due to misplacement.

• Labor savings and improved safety: Since surveying and guidance work that previously required multiple people can be done by one person, it helps alleviate labor shortages and reduce personnel costs. Also, fewer people need to approach operating machinery, lowering the risk of contact or fall accidents. Dangerous snapping work at heights or in deep excavations is minimized, reducing workers’ physical burden. Because even inexperienced workers without surveying expertise can perform position-setting by following the app’s on-screen guidance, the burden of training technicians is greatly reduced.

• Enhanced quality control through data utilization: During GNSS-guided operations, data such as positioning errors and arrival times at each point are automatically recorded digitally, allowing construction managers to review logs later for quality control. This eliminates the need for handwritten field notebooks and enables tracing of error causes if problems occur. Visualizing the construction process with data contributes to improved site management.

With the advent of LRTK, pile-guidance, which once relied on craftsmen-level surveying expertise, is being transformed into a task anyone can perform using digital navigation. LRTK, which combines the ease of “smartphone surveying” with centimeter-level positioning accuracy comparable to dedicated equipment, is a powerful tool for promoting digital transformation (DX) in the construction industry. These advanced technologies align with the Ministry of Land, Infrastructure, Transport and Tourism’s i-Construction policy and are expected to be a solution that improves productivity while ensuring quality.

LRTK, which enables pile-driving without “getting lost,” can be applied not only to foundation work but to various position-setting tasks. In fact, beyond pile driving, AR navigation is being used for many types of simple surveying, such as building layout, machine installation positioning support, locating underground utilities, and as-built inspections. Furthermore, AR guidance technology is expected to find increasing application in areas such as machinery autonomous control and infrastructure inspection. If you feel uncertain or inefficient about on-site position-setting, try smartphone surveying with LRTK for accurate and speedy pile-guidance. Experience the efficiency and peace of mind provided by cutting-edge technology on your site.

Frequently asked questions

Q: What kind of product is LRTK?

A: LRTK is a positioning system consisting of an ultra-compact RTK-GNSS receiver that can be attached to a smartphone, a dedicated app, and a cloud service. Attaching the palm-sized device to a smartphone enables centimeter-level positioning and intuitive AR-based position guidance.

Q: Can it be used without specialized surveying experience?

A: Yes. The LRTK app is designed to be user-friendly for beginners, and you can navigate pile positions by following on-screen instructions. No complicated calculations or expert knowledge are required, so even those with little field experience can become proficient after a short training period.

Q: Can it be used for tasks other than pile driving?

A: Of course. LRTK can be applied to layout of building foundations, locating installation points for temporary structures, establishing reference points in roadworks, locating buried pipes, and other surveying and position-setting tasks. It helps visualize coordinate points from drawings on site, making it a versatile tool for streamlining many types of field surveying.

Q: How accurate is the positioning?

A: Accuracy depends on environmental conditions, but generally horizontal positions can be accurate to within ±a few centimeters (±a few inches), and vertical accuracy ranges from a few centimeters to less than 10 cm (less than 3.9 in). This is a dramatic improvement over standalone GPS and is sufficient for pile driving and layout tasks on construction sites.

Q: Does rain or surrounding environment affect positioning accuracy?

A: Since the system uses satellite signals, in open outdoor environments light rain or clouds have little effect on positioning accuracy. However, environments where the sky view is blocked—such as inside forests or surrounded by high-rise buildings—can hinder satellite reception and reduce accuracy. In such cases, positioning may take longer or errors may increase, so consider changing the observation location as needed. The LRTK device is dust- and water-resistant, so it operates fine in light rain.

Q: What do I need to use it?

A: You need only the LRTK device itself and a compatible smartphone. The app is available for both Android and iPhone. RTK positioning requires receiving correction information from a reference station, but LRTK supports network RTK via mobile communications, so high-precision positioning is possible wherever the smartphone has mobile connectivity. In Japan, LRTK also supports the high-precision augmentation service (CLAS) provided by the Quasi-Zenith Satellite System (Michibiki), enabling centimeter-level positioning even without an internet connection within supported areas.

Q: I’m concerned about introduction costs—does it offer cost-effectiveness?

A: LRTK’s introduction cost is generally lower than purchasing a full set of dedicated surveying equipment, and it makes use of existing smartphones, reducing waste. It can also reduce the frequency of outsourcing to surveying firms, lowering operational costs. Considering labor and time savings that improve productivity, adopting LRTK can be a cost-effective investment.

Q: I’m worried the operation will be difficult. Is there support available?

A: The LRTK provider offers device setup support at initial deployment, as well as training materials and manuals for app usage. A helpdesk is also available, so even those unfamiliar with the equipment can adopt it with confidence. If issues arise on site, you can receive advice from support, so there is no need to worry.