Coordinate Navigation Revolution for Piling! Achieve Unambiguous Pile Positioning Guidance with the LRTK App

Table of Contents

• Current status and challenges of piling work

• What is pile positioning guidance by coordinate navigation

• Precise positioning enabled by high-precision GPS (RTK) technology

• The piling revolution brought by the LRTK app

• Steps for piling work using the LRTK app

• Expanded possibilities for simple surveying with LRTK

• FAQ

Current status and challenges of piling work

When performing piling work on civil engineering or construction sites, it is most important to drive piles at the exact positions specified by the design. Traditionally, this location-setting work has been done by surveyors who determine positions on site based on coordinates on drawings, mark the ground (make marks) or drive wooden stakes as reference points, and then machine operators install piles using those markers. However, this method requires labor and time and carries a risk of errors.

For example, while survey personnel measure distances and angles with a tape measure or a transit (tripod-mounted optical surveying instrument) to determine pile positions, the marked position can be shifted due to misreading numbers or insufficient communication. Also, if a reference stake that was placed moves or is pulled out during work, it can have a major impact on construction accuracy. If pile positions are wrong, subsequent processes can face problems such as “installation positions don’t match,” leading to re-driving piles or repair work and resulting losses.

Moreover, topographical constraints have been an issue. On slopes or near water, it can be physically difficult to install stakes or markings, making the traditional method of locating piles itself challenging. On large sites, machine guidance using GNSS (satellite positioning) mounted on heavy machinery to guide operators has begun to be introduced. However, dedicated high-precision GNSS equipment and systems are expensive and have not yet spread to small- and medium-sized sites. There is also a serious shortage of skilled survey technicians, and many sites cannot allocate enough personnel or time for stakeout. As a result, ensuring pile-position accuracy is a major challenge at many construction sites. Traditional optical surveying-based pile layout takes time and reduces productivity. In one comparison, the time required for traditional surveying was reported to be as much as about six times that of the latest digital surveying methods. Against this backdrop, the field has been demanding new methods that can guide pile positions more efficiently and accurately.

What is pile positioning guidance by coordinate navigation

A key solution attracting attention to solve the above challenges is pile positioning guidance by coordinate navigation. Coordinate navigation is a method that directly navigates people or machines to target coordinates from survey data; simply put, it is a technology that guides you to specified coordinates like a car navigation system. By using high-precision positioning devices to navigate directly to the pile coordinates recorded on design drawings in the field, you can omit intermediate marking work while maintaining accuracy.

For example, if you pre-set the coordinates of the point where a pile should be driven into the device, you can reach the pile position on site simply by following the direction and distance indicated by the device. Since workers only need to follow arrows or numbers on the screen, a single person can locate the pile position accurately without getting lost. In initiatives such as the Ministry of Land, Infrastructure, Transport and Tourism’s “ICT construction” and “i-Construction,” improving construction accuracy using GNSS is an important theme, and pile positioning guidance by coordinate navigation has emerged as a solution in that context. By reducing reliance on veteran workers’ intuition and experience and enabling anyone to place piles with the same accuracy, this technology is bringing a new common sense to piling work.

Precise positioning enabled by high-precision GPS (RTK) technology

The core technology supporting this coordinate navigation is RTK positioning. RTK (Real Time Kinematic) refers to a technique in GNSS that corrects satellite positioning errors in real time using correction data from a base station, enabling positioning with centimeter-level accuracy. Simply put, it is an ultra-high-precision GPS usable on site. Ordinary smartphone GPS has errors of several meters, but with an RTK-capable high-precision GNSS receiver, horizontal accuracy of about ±2 cm (±0.8 in) and vertical accuracy of a few centimeters can be achieved. Note that immediately after powering on the receiver, positioning accuracy is still on the order of several meters, but when it receives augmentation signals from satellites and achieves a Fix solution (Fix: high-precision solution), the aforementioned ±2 cm (±0.8 in) accuracy becomes available. With LRTK, a Fix state is typically reached in about 1–2 minutes after startup, enabling high-precision piling guidance from that point.

By using RTK positioning, you can navigate directly to target coordinates on survey data, eliminating the need for intermediate marking or re-measurement. Because correction information removes errors and high accuracy is guaranteed, piling work that previously proceeded cautiously with repeated position checks can be done quickly and reliably. In other words, the spread of RTK technology has ushered in a kind of revolution in pile positioning guidance.

The piling revolution brought by the LRTK app

The LRTK app makes the above RTK-based coordinate navigation easily usable on site. The LRTK system consists of a high-precision GNSS receiver terminal called the “LRTK Phone,” the “LRTK app” that runs on a smartphone, and the “LRTK Cloud” accessible from a PC. For example, by simply attaching an LRTK receiver weighing about 125 g to an iPhone, the device becomes a compact surveying instrument that fits in your pocket and can be taken out and used whenever needed. This makes it possible for everyone on site to carry a high-precision positioning terminal individually.

The actual operation of the LRTK app is very simple and intuitive. The smartphone screen shows your current position and target points on a map or compass display, so even first-time users can use it without confusion. Without specialized surveying knowledge, workers can reach piling points simply by following the app’s instructions, allowing inexperienced staff to become effective on site. Tasks that used to be outsourced to the survey team can be handled by the site workers themselves, resulting in significant labor savings and efficiency gains. Also, because one person can work alone, coordination with nearby heavy machinery becomes easier, improving on-site safety. Reducing the need to walk around the site for long periods to survey also contributes to lowering the risk of accidents and troubles.

Furthermore, the LRTK app is linked to the cloud; if you upload and share design coordinate data (such as pile positions) in advance, you can call up and start guiding to a point on site with the touch of a button. After finishing pile installation, you can immediately save and share the results (installed pile coordinates and photos) to the cloud, simplifying office reporting. Since data are centrally managed in the cloud, progress checks and team information sharing become smooth. Because coordinates and result data accumulate in the cloud, multiple workers can work while referring to the same information. For example, if field-surveyed results are instantly shared to the cloud, progress can be checked or feedback provided from a remote office.

The LRTK app also features AR (augmented reality). By overlaying design target points and directional guidance on the smartphone camera image, you can intuitively see “where the targeted pile position is in the real world” just by looking at the screen. You can visually identify the approximate direction even from a distant point, then switch to a detailed guidance screen as you approach to refine position to the centimeter level. This AR visualization lets you compare drawings and the site without hesitation and drive piles without getting lost.

Moreover, LRTK brings high-precision positioning to sites where introducing expensive dedicated surveying equipment was difficult. Even small- and medium-scale construction sites that struggled to ensure surveying accuracy due to cost or manpower constraints can expect an uplift in construction quality by using LRTK.

With the advent of LRTK, piling work has become dramatically smarter. Position setting that relied on experienced workers’ intuition has become a task anyone can perform, and it is faster and more accurate than before. A change that can rightly be called a “piling revolution” is beginning to occur on sites.

Steps for piling work using the LRTK app

Using the LRTK app, pile position guidance proceeds in the following flow.

• Prepare coordinate data: First, upload the coordinate data for planned piling points obtained from design drawings or prior surveys to the LRTK Cloud. By registering and sharing point coordinates from CSV files or CAD data, you can call them up on site immediately.

• Power on and connect the GNSS terminal: Upon arrival at the site, power on the LRTK high-precision GNSS terminal (LRTK Phone) and connect it to your smartphone via Bluetooth. If you place the terminal where the sky is open, it will acquire satellites and start positioning in about one minute.

• Select the point to be guided: Launch the LRTK app on your smartphone and select the piling point you want to navigate to. Choose the relevant point from the coordinate list synced with the cloud and start navigation.

• Coarse guidance: When coordinate navigation starts, an arrow indicating the target direction and the distance from your current position appear on the smartphone screen. Walk following that guidance and move in the indicated direction. Since direction and distance are updated in real time, you can reach the vicinity without getting lost even while walking alone.

• Precise alignment: As you approach the target, the screen switches to a more precise guidance mode. When you are within a remaining error range of several tens of centimeters to a few centimeters, the arrows and distance readouts become more detailed, allowing you to align to centimeter-level. If necessary, switch to AR mode to display a target marker on the camera image and visually confirm position while aligning.

• Drive the pile: Once you stand exactly at the position indicated by the smartphone, that is the point to drive the pile. Mark the spot and drive the pile. If preparatory work has been done, identifying the pile position can be completed in just a few minutes.

• Record the results: After driving the pile, record the completion of that point in the LRTK app. If needed, take photos with the smartphone camera at the point and save them to the cloud as records with high-precision coordinate information. These records are useful for construction management and later inspections.

By using the LRTK app in this way, what used to be a complicated piling workflow can be completed with simple steps. Tasks that previously required experienced surveyors can be carried out on site by workers themselves in a short time.

Expanded possibilities for simple surveying with LRTK

LRTK is also powerful for various kinds of simple surveying on site beyond piling. For example, you can instantly measure the coordinates of arbitrary points and reflect them in drawing data, measure heights at multiple points and calculate earthwork volumes for fills and excavations on the spot, and more—the range of applications is very wide. Tasks that used to require dedicated surveying equipment or advanced skills can be handled by site staff in a short time with LRTK. It is truly a tool that promotes digital transformation (DX) on site.

LRTK is also useful for tasks such as confirming the positions of boundary stakes or locating buried objects. Even for periodic inspections where photos are taken from the same point to compare changes over time, LRTK allows you to shoot from almost the same point using position information, greatly improving recording accuracy.

As LRTK-based simple surveying spreads, decision-making speed on site will dramatically improve. For example, there are reports that piling layout work that previously required 2–3 surveyors and half a day was completed by one person in less than an hour after introducing LRTK. Because checking pile positions and measuring as-built shapes can be done on the spot rather than outsourcing and waiting for results, rework and waiting time are reduced, shortening schedules and cutting costs. As smartphone surveying technology continues to spread, the conventions of surveying and piling work will change significantly. LRTK is leading that transformation and strongly promoting on-site DX. The world LRTK aims for is one where anyone can perform accurate surveying on site. Experience this new, unconstrained, smart piling and surveying method on your site.

FAQ

Q1. What is a pile positioning guidance app?

A. It is a smartphone app that guides workers to pile locations (coordinates) on drawings. It uses positioning technologies such as GPS and RTK to display arrows and distances on the screen and guide users to designated points. The app eliminates traditional tape measures and transits for surveying and enables anyone to easily find accurate pile positions.

Q2. Why is the LRTK app high-precision?

A. LRTK adopts RTK (Real Time Kinematic) high-precision GNSS, enabling position determination with centimeter-level accuracy. Correction information from base stations corrects satellite positioning errors in real time, so it does not deviate by several meters like ordinary smartphone GPS. Both horizontal and vertical accuracy are within a few centimeters, making it suitable for tasks requiring height control such as foundations. Therefore, it can be used with confidence for tasks like piling that require high accuracy.

Q3. Do I need special skills or equipment to use the LRTK app?

A. No special surveying qualifications or advanced knowledge are required. Operation is simply following the smartphone screen guidance, so even first-time users can learn quickly. However, to fully utilize the LRTK app you need a dedicated high-precision GNSS receiver (LRTK Phone) and a compatible smartphone such as an iPhone. Once these are set up, you can perform pile positioning guidance with intuitive operation.

Q4. Can it be used in bad weather or environments with obstacles?

A. Basically, it can be used outdoors where the sky is relatively open. Cloudy weather or light rain generally does not significantly affect GNSS positioning. However, in places where satellite signals are blocked—such as dense forests or canyons between tall buildings—positioning accuracy may degrade or reception may be lost. In extreme weather such as heavy rain or thunderstorms, it is advisable to refrain from work for safety reasons. Please use it in environments where the sky is sufficiently visible.

Q5. How else can LRTK be used besides piling?

A. LRTK is useful for various simple surveying tasks beyond piling. For example, you can measure coordinates of arbitrary points and reflect them in drawings, measure elevation differences to calculate earthwork volumes, and quickly obtain data on site. It also supports tasks such as locating control points, as-built measurements, and embedding high-precision location data in construction photos—work that previously required specialized equipment can now be done easily. In short, LRTK supports general on-site surveying with a smartphone.

Q6. On which devices is the LRTK app available?

A. Currently, the LRTK app supports iOS (Apple’s iPhone/iPad). The dedicated LRTK Phone receiver connects to an iPhone via Bluetooth, and the LRTK app on the iPhone is used for pile positioning guidance. An Android version is being considered for future support.

Q7. How much does work efficiency improve by introducing LRTK?

A. Effects vary by site scale and tasks, but significant efficiency gains are expected for pile layout. There is no need to gather a survey team, and one person can complete the work, reducing staffing coordination. In actual cases, pile layout that previously took 2–3 people half a day was completed by one person in less than an hour using LRTK. Shorter work times lead directly to shorter schedules and reduced labor costs, contributing to overall productivity improvements on site.