Site Supervisors Take Note: How to Aim for Zero Construction Errors in RTK Piling

Table of Contents

• Importance of piling and traditional challenges

• Evolution of piling techniques using RTK and AR

• Features of LRTK and concrete use cases

• Construction case studies and benefits of adoption

• Simple surveying with LRTK

• FAQ

When performing piling work on a construction site, even a small positional deviation can lead to serious construction errors later on. In foundation work, ensuring piles are installed at the exact positions and depths specified in the design secures the safety and stability of the structure. However, using traditional methods to accurately locate pile positions on site required skilled surveying techniques and was prone to human error. This article explains, for site supervisors, how to use RTK piling techniques to aim for zero construction mistakes.

Importance of piling and traditional challenges

Piling in construction is an extremely important task that supports the foundations of buildings and structures. By driving piles into the ground and placing them at the positions and depths specified in the design, the stability of the structure is ensured. However, there have been several challenges with traditional piling work.

First is the difficulty of measuring and marking pile positions. Design drawings indicate pile locations by coordinates, but accurately identifying those positions on the actual site required advanced surveying techniques and considerable effort. Typically, a surveying team uses tape measures or a total station to measure distances from reference points and places marks (pile markers or batter boards) on the ground. Heavy equipment operators then use these markers as references when driving piles. But manual positioning work is time-consuming, and surveying itself can become difficult depending on weather and terrain. Also, because humans perform the measurements, surveying errors and positional deviations are inevitable, and even slight offsets can lead to construction mistakes later on.

There are also safety concerns. Marking pile positions is done within areas where heavy equipment operates, so if a surveying worker accidentally approaches machinery, it can be extremely dangerous. Especially on slopes or in muddy areas where footing is poor, installing physical pile markers is hazardous and sometimes impossible. In this way, traditional methods posed challenges in terms of positional accuracy, work efficiency, and safety—issues that have troubled site supervisors.

Evolution of piling techniques using RTK and AR

Recently, advances in positioning technology and digital tools have greatly evolved methods for locating and guiding piling work. The key technologies are RTK and AR. Below is a brief explanation of each.

• RTK (Real-Time Kinematic): A type of satellite positioning (GNSS, i.e., high-precision GPS) that provides centimeter-level positioning accuracy in real time. Standard smartphone GPS can have errors of several meters, but RTK uses correction data from a base station to reduce errors to within a few centimeters. In other words, when locating pile positions on site, RTK can provide current position information with high precision comparable to dedicated surveying equipment. In Japan, augmentation signals provided by the Quasi-Zenith Satellite System "Michibiki" (such as CLAS) have made RTK positioning easier to use even without installing a dedicated base station.

• AR (Augmented Reality): A technology that overlays digital information on real-world images displayed on a smartphone or tablet screen. Familiar examples include mobile games that make characters (like Pokémon) appear over the camera view, or map apps that overlay arrows on a live camera view for navigation. On construction sites, AR can visually indicate “drive the pile here” directly on the screen. That is, pile position data from the drawings can be overlaid on the smartphone camera view so that the worker can see exactly where to drive the pile just by looking at the screen. Traditionally, workers had to mentally match drawings to the site to determine positions, but AR allows anyone to instantly grasp pile locations at a glance.

Combining high-precision positioning from RTK with visual guidance from AR is evolving piling work into a next-generation style that could be called “piling navigation.” The way it provides real-time guidance of pile positions on site based on highly accurate location information is like a car navigation system for construction sites. For example, a supervisor can walk the site with a tablet in hand and be guided to the target pile position by on-screen arrows and markers. As they approach the target, displays such as “remaining X cm” appear, and when they reach the exact spot the on-screen marker aligns perfectly. With RTK × AR, even inexperienced personnel can accurately identify pile positions without relying on the intuition of veterans, enabling high-precision construction.

Features of LRTK and concrete use cases

Now let’s look at LRTK, a notable solution that uses RTK and AR for pile guidance. LRTK is a system developed by Refexia, a venture originating from Tokyo Institute of Technology. It is an all-in-one site DX tool that realizes high-precision positioning and intuitive AR guidance using smartphones and tablets. By attaching a dedicated ultra-compact RTK-GNSS receiver to a smartphone, it becomes a compact surveying instrument that fits in a pocket and can obtain centimeter-level current positions in real time. In addition, its dedicated app and cloud service enable integrated management of positioning data and design coordinates as well as AR-based guidance.

Main features of LRTK:

• High-precision positioning: RTK-GNSS allows pile positions to be identified in centimeter units (half-inch accuracy). Precise pile center positions that were difficult with conventional GPS can now be obtained easily with a smartphone. This minimizes deviations from the design coordinates set in advance.

• AR visualization of pile positions: The LRTK app can display virtual piles (AR piles) at the configured positions on the screen. For example, if you select coordinates on the drawing where a pile is to be driven, a virtual pile in a color such as pink will appear at that point in the camera view. Looking at the actual ground through the smartphone, the virtual pile appears to stand on the site, making the exact position obvious. Even in dark areas or vacant lots with no landmarks, you won’t miss the point where the pile should be driven.

• Coordinate navigation function: The app has a coordinate navigation function that guides you to the target coordinates in real time. If you register pile coordinate data to the cloud in advance, on site you can simply select the point and the app will display arrows and distance to guide the worker. When moving to a distant point, an arrow showing the direction to go appears on the screen; as you get closer, the display switches to finer distance information and finally tells you “this is the target point.” This convenient function allows you to reach the exact point without getting lost.

• Overcoming physical constraints: One advantage of AR pile display is that it enables locating positions even where physical pile markers cannot be installed. For example, where you cannot drive a marker into hard concrete or where it’s dangerous to approach a steep slope, you can confirm the position by placing a virtual pile from a safe distance. Situations that previously had to be abandoned can be handled with digital display.

• Ease of use and portability: Conventional high-precision surveying equipment and pile guidance systems required bulky setups, but LRTK only needs a smartphone and a small device. The receiver weighs about 125 g and simply attaches to a smartphone, so it won’t burden workers walking around the site. Its pocket-sized portability and quick accessibility are major advantages on site.

• Cloud integration: It is also characterized by the ability to share positioning data, site photos, and point cloud data to the cloud in real time. Pile coordinate data can be managed centrally in the cloud, smoothing everything from pre-construction preparation to post-construction record organization. Position data recorded on site are instantly shared with the office, aiding subsequent process planning and report preparation.

Concrete usage flow when using LRTK for pile guidance:

• Design data preparation: Register the coordinates of piles to be installed in the project to the LRTK cloud system. Preparing an Excel coordinate list and uploading it to the cloud completes the site data preparation.

• Device and app setup: On site, attach the RTK-GNSS receiver (LRTK device) to a smartphone or tablet and launch the LRTK app. The receiver acquires satellite signals and correction information, enabling high-precision positioning. Preparation is complete in a matter of tens of seconds.

• Navigation to pile position: Select the target pile number or point in the app and a navigation display appears. Follow the arrow and distance guidance on the screen to walk to the target. For example, follow a display such as “5 m (16.4 ft) ahead to the northeast,” and as you approach the target the guidance becomes more detailed. Finally, the app will indicate pin-point instructions like “2 cm (0.8 in) left” or “This is it!” so you can reach the specified position accurately.

• Position confirmation and marking: When you reach the indicated point, confirm the virtual pile (AR pile) position in the smartphone camera view. If the virtual pile stands straight and aligns with the design position, that proves you are standing at the exact point. Mark the ground with spray paint as needed and drive the actual pile with the pile driver. If physical landmarks are desired, the AR pile allows you to use minimal physical markers.

• Recording and sharing: After driving each pile, take photos on site and save them in the app. Photos are automatically tagged with position information and synchronized to the cloud, so you can later digitally check whether each pile was driven within a few centimeters (within a few inches) of the design coordinates. Having photo-backed records facilitates quality control and reporting to the client.

As described above, LRTK allows people without surveying expertise to locate pile positions accurately simply by following smartphone screen instructions. It is truly a groundbreaking tool that realizes “anyone can locate pile positions.”

Construction case studies and benefits of adoption

On actual sites, reports are gradually emerging about the benefits that such high-precision piling guidance technologies bring. Let’s look at some expected use cases to see their effects.

Building foundation work example: On one construction project’s foundation piling, a surveying team used to mark pile positions with batter boards, and heavy equipment operators visually confirmed those marks before driving piles. After introducing LRTK, the site supervisor could check and mark pile positions one by one with a smartphone and instruct the heavy equipment operator alone. As a result, the time required per pile for positioning was greatly reduced and overall foundation progress accelerated. Tasks that used to take half a day for positioning were completed in a few hours, leading to cost reductions from reduced manpower. In addition, digital records provided evidence that “each pile was installed within a few centimeters (within a few inches) of the design position,” making explanations to clients smoother.

Slope civil engineering example: For slope reinforcement and river embankment works on steep slopes, workers used to have to descend the slope in safety harnesses to perform surveying and marking in dangerous postures when installing anchor piles. With LRTK’s AR pile display function, virtual piles can be displayed from safe flat ground or points away from the slope, so pile positions can be identified without having personnel enter dangerous slopes. At one site, an advanced method was tried where the positions indicated by AR piles were used as targets for a drone to spray paint the ground. This greatly reduced manual surveying work and cut significant time and labor.

The adoption benefits from these use cases can be summarized as follows:

• Improved accuracy: Centimeter-level guidance virtually eliminates pile positional deviations. Accurate construction per design prevents rework and errors caused by misaligned piles. This is particularly valuable for projects requiring strict positional accuracy, such as high-rise buildings and bridges.

• Increased work efficiency: The time required for surveying and positioning is dramatically reduced. For example, replacing conventional optical surveying for pile positioning with AR guidance has been verified to shorten work time to about 1/6 of the previous time. Because each worker can follow the navigation, tasks that once required multiple people can be done with minimal staff, improving overall speed.

• Reduced personnel and costs: The number of surveyors and assistant staff can be reduced, lowering labor costs. Because the system is easy to operate even by non-experts, it is suitable for sites struggling with labor shortages. Also, as the system is smartphone-based and relatively inexpensive, initial investment costs can be kept down (LRTK is priced reasonably, making one-per-person deployment realistic).

• Improved safety: There is no longer a need to force manual positioning in dangerous locations. AR allows position confirmation from safe zones, reducing accident risks around high places, slopes, and heavy equipment. Worker physical burden is also reduced, enabling safer work.

• Quality control and recordkeeping: Digital positioning data and photographic records make post-construction quality checks and reporting easier. Records show which pile was driven to which coordinate, which is useful for later additional work or inspections. Objective data as explanatory material for clients and regulatory authorities increases credibility.

• Versatility: LRTK can be used for many tasks beyond piling, such as layout marking, as-built measurements, locating buried objects, and overlaying 3D models on site. Once introduced, it serves as a multipurpose site DX tool. For example, you can perform point cloud surveys of the ground between piling tasks, or display expected completion models in AR to share with stakeholders.

Thus, high-precision piling guidance technologies represented by LRTK are solutions that realize the site ideal of “accurate, fast, and safe.” They can simultaneously solve long-standing challenges of ensuring positional accuracy, low work efficiency, labor shortages, and safety measures, and are increasingly anticipated by the field.

Simple surveying with LRTK

What’s appealing for those interested in advanced technologies is that LRTK is not a complex special device but a simple surveying tool you can use with a smartphone. With a high-precision RTK-GNSS receiver and a smartphone app, you can start using it right away, making it relatively easy to introduce even for first-timers. For adoption, it’s recommended to gather detailed information from the official website and product materials and consult about site applicability. If you want to try it, demo units and site trials are available so you can experience its accuracy and convenience before deciding. After contracting, order the small receiver device and install the app to complete setup. In many cases your existing smartphone can be used, and manufacturers provide support for setup and operation, so site staff unfamiliar with IT can start with confidence.

Once setup is complete, start using LRTK on site. It’s good to begin with small-scale piling as a trial and become accustomed to the operation. You should soon feel its effects. Site staff have commented that “it feels like a game to locate pile positions,” and many praise that accurate work can be done while enjoying it. If questions arise during operation, the support desk responds quickly, which is reassuring.

Introducing advanced technology not only improves site productivity but also contributes to work-style reform. Staff who were burdened by repetitive surveying tasks can reduce that load and spend more time on higher-value tasks. Site DX is progressing step by step, and even in the piling guidance field LRTK is making “sites where anyone can pile accurately” a reality.

If you are concerned about improving piling accuracy or efficiency, please consider LRTK’s high-precision piling guidance technology. It is easy for first-time users to handle and will be a reliable ally on site. With its unparalleled piling accuracy and speedy construction, LRTK will be a powerful supporter to help make your projects successful. Harness cutting-edge technology and aim for a site with zero construction mistakes!

FAQ

Q. What is RTK? How is it different from traditional GPS? A. RTK stands for Real-Time Kinematic and is a high-precision positioning technique using satellite positioning (GNSS). While ordinary GPS positioning can have meter-level errors, RTK uses correction information from a reference station to reduce errors to centimeter levels. In other words, RTK enables the precise real-time positioning required on construction sites.

Q. What are the benefits of introducing RTK to piling work? A. The biggest benefit is a dramatic improvement in pile positioning accuracy. With RTK, piles can be driven at the positions shown in the drawings, preventing errors and rework due to misalignment. It also greatly reduces the effort and time required for surveying. Tasks like setting up batter boards or layout marking that used to require multiple people become unnecessary, and positioning can be completed quickly. The result is shorter schedules and reduced staffing, and it contributes to safety by reducing worker burden and accident risk.

Q. Do I need expensive equipment to use RTK? Can a smartphone substitute? A. Traditionally RTK positioning required dedicated expensive GNSS receivers and base stations, but recently affordable products that can be used with smartphones have appeared. For example, LRTK is a type that attaches a small RTK receiver to a smartphone, allowing much lower cost and more compact operation than conventional equipment. By using high-precision positioning services (for example, augmentation signals from Michibiki or correction data via mobile networks), centimeter-level positioning on a smartphone is possible without installing a large base station.

Q. Can people without equipment operation or surveying knowledge use it? A. Yes. LRTK is designed to be usable by those without specialized knowledge. You just follow the on-screen guides like arrows and virtual piles, so operation is intuitive. After basic training or explanation, site staff without surveying experience can quickly use it on site. Also, a support system is available for assistance when needed, so you can start using it with confidence.

Q. What other uses does LRTK have besides piling? A. LRTK can be applied to various site tasks beyond piling. For example, it can be used for layout marking (setting out), as-built measurements for roads or development sites, high-precision recording and confirmation of buried objects, and 3D point-cloud scans of terrain and structures when combined with an iPhone LiDAR function. You can also overlay design drawings or BIM models in AR on site to share completion images. Once introduced, it is useful for a wide range of surveying and construction management tasks, making LRTK an attractive multipurpose tool.