A Beginner-Friendly Guide to LRTK High-Precision Pile Driving Guidance Technology

This article takes an average of 2 minutes and 30 seconds to read

Published February 28, 2025

The Importance of Pile Driving and Traditional Challenges

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Pile driving in construction is an extremely important task that supports the foundation of buildings and structures. By accurately driving piles into the ground at the correct location and depth as specified in the design, the safety and stability of the building are ensured. However, traditional pile driving operations have had several challenges.

First is the difficulty of positioning. The pile locations are indicated by coordinates on the drawings, but accurately identifying these positions on the actual site required skilled surveying techniques. Traditionally, a surveying team would use tools such as measuring tapes or total stations to measure distances from reference points and mark the ground with markers (pile stakes or string lines). On-site, heavy equipment operators would use these markers as guides to drive the piles. However, manual positioning was time-consuming and labor-intensive, and depending on the weather or terrain, surveying tasks themselves could be difficult. Furthermore, since the work was done manually, there was always the risk of surveying errors and position discrepancies, and even a slight misalignment could lead to construction mistakes later on.

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Another issue is safety. The marking of pile positions is carried out in areas where heavy equipment operates, posing a danger if workers accidentally approach the machinery. It is especially hazardous when marking pile positions on slopes or muddy ground, where it may be physically difficult to install the markers. These challenges in traditional methods have led to the need for new technologies that can make pile driving operations more accurate, efficient, and safe.

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The Evolution of Pile Driving Technology Using RTK and AR

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In recent years, the development of positioning and digital technologies has greatly advanced the processes of pile positioning and guidance. The key to this progress lies in the use of RTK and AR. To make it easy for beginners to understand, let's briefly explain what each of these technologies is.

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• RTK (Real-Time Kinematic): RTK is a satellite positioning technology (GNSS, also known as high-precision GPS) that provides centimeter-level positioning accuracy in real-time. While the GPS in standard smartphones may have errors of several meters, RTK uses correction data from a base station to reduce this error to within a few centimeters. This allows for positioning accuracy comparable to traditional surveying equipment when identifying pile positions on construction sites. In Japan, the environment for using RTK positioning has improved with the reinforcement signals (such as CLAS) provided by the quasi-zenith satellite "Michibiki," making it easier to utilize RTK without the need for dedicated base stations.

• AR (Augmented Reality): AR, or augmented reality, is a technology that overlays digital information onto the real world as viewed through a smartphone or tablet camera. Common examples include games that display Pokémon in the camera view or map apps that superimpose arrows for navigation. In construction, AR can be used to visually display the instruction "drive the pile here" on the screen. By overlaying pile position data from drawings onto the real-world footage using AR, workers can intuitively identify the exact points where piles should be driven. Traditionally, workers would compare the drawing to the physical site in their minds to identify positions, but with AR, anyone can immediately understand the correct location.

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By combining RTK and AR, pile driving guidance has evolved into a new stage that could be called "pile driving navigation." Based on high-precision location data, it provides real-time guidance on pile positions on-site, much like a navigation system for construction sites. For example, the operator can walk around the site holding a tablet and follow the arrows and guides displayed on the screen to navigate to the correct pile location. As the operator approaches the target point, a display may show "○cm remaining" to indicate proximity to the goal, and when they reach the exact position, the mark on the screen aligns perfectly. With this combination of RTK and AR technology, even inexperienced workers can accurately identify pile positions without getting lost, and precise construction can be achieved without relying on the intuition of seasoned experts.
 

Features of LRTK and Specific Use Cases

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Now, let's take a look at LRTK, which is gaining attention as a concrete solution for pile driving guidance using RTK and AR technologies. LRTK is a system developed by Refixia, a venture originating from the Tokyo Institute of Technology. It is an all-in-one field DX tool that enables high-precision positioning and intuitive guidance using AR via smartphones or tablets. By attaching a specialized ultra-compact RTK-GNSS receiver to the smartphone, it becomes a portable surveying tool that fits in your pocket and provides centimeter-level positioning accuracy. Additionally, with the dedicated app and cloud service, it offers an integrated solution for managing positioning data, design coordinates, and AR display.

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Key Features of LRTK:

• High-Precision Positioning: With RTK-GNSS, pile driving positions can be identified with centimeter-level accuracy. Unlike traditional GPS, which struggles with precise pile center positioning, LRTK allows for easy measurement using a smartphone. This minimizes deviations on-site compared to pre-set design coordinates.

• AR Visualization of Pile Positions: The LRTK app allows you to display virtual piles (AR piles) on the screen at the designated position. For example, when you select a coordinate on the drawing, a marker (virtual pile) appears in pink or another color overlaid on the camera view. The worker can view the actual ground through the smartphone, where the virtual pile is clearly visible at the correct location. This is effective even in dark areas or empty lots with no markers, ensuring that the target pile location is not missed.

• Coordinate Navigation Feature: LRTK also includes a coordinate navigation function that guides you to the target coordinates. If pile position coordinates are pre-registered in the cloud, you simply select the point on-site, and the app will display real-time direction and distance, guiding the worker. When moving farther away, arrows will indicate the direction, and as you get closer, the distance display becomes more precise, ultimately telling you, "This is the target location." It’s an incredibly convenient feature for precise navigation without getting lost.

• Overcoming Physical Constraints: The advantage of AR pile display is that it enables position marking even in locations where it’s physically impossible to install a pile marker. For example, if it’s difficult to drive a pile marker into hard concrete or in dangerous areas like steep slopes, virtual piles can be displayed from a safe distance to confirm the position. This digital display option can handle situations that would have been impossible with traditional methods.

• Ease of Use and Portability: Traditional high-precision surveying equipment and pile driving guidance systems required bulky devices, but LRTK is fully functional with just a smartphone and a compact device. The receiver, weighing only about 125g, can be easily attached to the smartphone, so it doesn’t burden workers who need to move around the site. The ease of carrying it in a pocket and quickly pulling it out when needed makes it highly practical for field use.

• Cloud Integration: LRTK allows immediate sharing of positioning data, photos taken on-site, point cloud data, and more through the cloud. The coordinates of pile points can also be managed in the cloud, streamlining preparation and post-operation record-keeping. The pile position data recorded on-site is instantly shared with the office, facilitating later discussions and the creation of reports for the subsequent stages of the project.

Specific Use Case: The Process of Using LRTK for Pile Driving Guidance​

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1. Preparation of Design Data: The coordinates for the pile positions (as per the design drawings) are registered in the LRTK cloud system for the construction project. Simply prepare a coordinate list in Excel or similar, upload it, and the data for use on-site is ready.

2. Device Setup: On-site, attach the RTK-GNSS receiver (LRTK device) to a smartphone or tablet and launch the LRTK app. The receiver communicates with satellites and acquires correction data to enable high-precision positioning. The setup is ready in just a few seconds.

3. Guiding to the Pile Location: Select the desired pile number or location in the app, and the navigation will be displayed on the screen. Follow the arrows and distance indicators to walk toward the target. For example, it might show "5 meters to the northeast," and you move accordingly. As you get closer to the target, the guidance becomes more precise, with the final instruction saying something like "2 cm remaining" or "You’ve reached the target!"

4. Position Confirmation and Marking: When you reach the indicated location, check the camera feed on your smartphone screen. You will visually confirm that the virtual pile (AR pile) appears at the correct location, as per the design. If it is aligned properly, it confirms that you are standing at the precise spot. You can then mark the ground at that location or, if needed, use the pile driver to install the actual pile. If you need markers around the area, AR piles can be used as a substitute, minimizing the need to install physical markers.

5. Recording and Sharing: After the pile is driven, take a photo of the location and save it in the app. The position data, along with the photo, will be uploaded to the cloud, allowing construction managers to digitally check all pile positions later. This increases the reliability of the construction records.

As shown above, with LRTK, even individuals without surveying expertise can accurately determine pile positions simply by following the instructions on the smartphone screen. It is truly an innovative tool that enables "anyone to accurately determine pile positions."

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Construction Case Studies and Benefits of Implementation

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In actual construction sites, the benefits of this high-precision pile driving guidance technology have started to be reported. Let’s explore its effects through a few potential construction case studies.

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Case Study 1: Use in Building Foundation Work

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In a foundation pile construction for a building, traditional methods involved a team of surveyors marking pile positions with string lines, and heavy equipment operators visually confirming and driving the piles. After the introduction of LRTK, the site supervisor was able to independently verify and mark pile positions with a smartphone, giving instructions to the heavy equipment operator. As a result, the time required for positioning each pile was significantly reduced, accelerating the progress of the entire foundation work. The pile positioning, which previously took half a day, was completed in just a few hours, and the reduction in personnel also led to cost savings. Additionally, digital records allowed them to later demonstrate, as evidence, that the piles were installed within a few centimeters of the design positions, making communication with the client smoother.

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Case Study 2: Use in Civil Engineering on Slopes

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In projects such as steep slope embankment work or river levee reinforcement, anchor piles or pile driving may be required. Traditionally, indicating pile positions on dangerous slopes was challenging, and it was necessary for personnel to descend using safety harnesses to conduct the survey. By utilizing LRTK’s AR pile display feature, virtual piles can be shown from safe locations away from the slope, allowing for pile position identification without requiring personnel to enter hazardous areas. This ensures the safety of the workers while allowing accurate positioning. In one civil engineering project, an advanced method was tested where paint was sprayed from a drone to mark the positions indicated by the AR piles. As a result, manual surveying tasks were greatly reduced, leading to significant cuts in both work time and effort.

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The benefits of implementation gained from the above use cases can be summarized as follows:

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• Improved Accuracy: With centimeter-level guidance, pile position deviations are almost eliminated. This enables precise construction according to the design drawings and prevents structural reinforcement rework or construction errors caused by pile misalignment. This is particularly effective in projects that require strict position accuracy, such as high-rise buildings and bridges.

• Increased Work Efficiency: The time required for surveying and positioning tasks is drastically reduced. For example, replacing traditional optical surveying with AR guidance for pile positioning resulted in a verification finding where work time was reduced to one-sixth of the previous method. Since each person can follow the navigation, tasks that once required multiple workers are now completed faster with a minimal number of people.

• Reduced Workforce and Costs: Reducing the number of surveyors and support staff leads to lower labor costs. Since even non-experts can handle the system, it is easier to implement in sites with a shortage of skilled workers. Additionally, because the equipment is smartphone-based and affordable, initial investment costs are kept low (LRTK is reasonably priced, making it feasible to equip each worker with a device).

• Enhanced Safety: There is no need to manually position pile locations in hazardous areas. With AR, position verification can be done from a safe zone, reducing the risk of accidents around high places, slopes, or heavy machinery. This also reduces the burden on workers, allowing them to work more safely and confidently.

• Quality Control and Record Keeping: Digital positioning data and photo records are saved, making post-construction quality inspections and reporting easier. A history of which pile was placed at which coordinates remains, and this data is useful for later position verification or during additional work. It also increases reliability when providing objective data for explanations to clients or regulatory agencies.

• Versatility: LRTK can be used for a wide range of tasks beyond pile driving, including layout marking, as-built measurement, checking the positions of buried objects, and overlaying 3D models on-site. Once implemented, it serves as a multifunctional DX tool for the site. For example, you can perform ground point cloud surveys between pile driving tasks or display AR renderings of the finished design to share with stakeholders.

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In this way, high-precision pile driving guidance technology, represented by LRTK, can be seen as a solution that fulfills the ideal of "accurate, fast, and safe" construction sites. It effectively solves traditional challenges such as ensuring position accuracy, improving work efficiency, addressing labor shortages, and enhancing safety measures, leading to growing expectations from the field.

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Information on How to Apply for and Implement LRTK
 

For those interested in LRTK, we encourage you to start gathering information about the implementation process. Fortunately, LRTK is not a complex specialized device and can be relatively easy to begin using, which is one of its appealing features. The process of implementation is as follows:

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1. Information Gathering and Inquiries: Start by checking the official website and materials to learn more about LRTK. You'll find information about its features, implementation examples, and pricing plans. If you have any questions or need to confirm whether it’s suitable for your site, you can easily reach out through the contact form or phone support on the website.

2. Demo and Trial Usage: If you're unsure about how it will perform on an actual site, many technologies offer demo units or live demonstrations. For LRTK, you can request a demonstration or trial usage. By physically testing it, you’ll be able to experience its accuracy and convenience firsthand.

3. Implementation Procedure: Once you've decided to implement LRTK, you'll proceed with the contract for the required devices (RTK receiver) and app usage. You may be able to use your existing smartphone, but you will also receive guidance on recommended models. Support for initial setup and training on usage is available, so even those who are not tech-savvy can feel confident.

4. Start Using on-site: Once the setup is complete, you can begin using LRTK on-site. Start with a small-scale pile driving trial to get familiar with the operation. You’ll soon feel the impact of its effectiveness. Many site staff have expressed that "it feels like a game" when positioning piles, which is a positive response. If any questions arise during use, the support team will quickly assist, providing peace of mind.

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Finally, the introduction of advanced technologies like LRTK not only leads to a productivity revolution on-site but also contributes to work style reform. Staff members who were previously overwhelmed by repetitive surveying tasks will experience a reduction in workload, allowing them to spend more time on higher-value activities. The digital transformation (DX) of construction sites is progressing step by step, and in the field of pile driving guidance, LRTK is enabling the realization of a "site where anyone can accurately drive piles."

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If you are facing challenges with the efficiency and accuracy of pile driving tasks, now is the perfect time to consider LRTK's high-precision pile driving guidance technology. Even beginners will find it easy to use, making it a reliable ally on-site. With its unmatched accuracy and speedy execution, LRTK will be a powerful supporter in guiding your project to success. By leveraging this new technology, which is shaping the future of construction sites, take your project to the next level.