RTK Piling Greatly Reduces Costs: Achieving Labor Cost Cuts and Shorter Construction Periods

Table of Contents

• What is RTK piling?

• Issues with conventional piling work

• Benefits brought by RTK piling

• Points for introducing RTK piling

• Simple surveying with LRTK

• FAQ

What is RTK piling?

In recent years, the construction industry has focused attention on "RTK piling," which uses RTK (Real-Time Kinematic) technology. RTK is a type of high-precision GNSS (Global Navigation Satellite System) positioning technology that features the ability to obtain centimeter-level position information (cm-level accuracy (half-inch accuracy)) in real time. By applying that accuracy and immediacy to piling work, the aim is to streamline pile positioning (setting survey stakes and locating foundation pile positions), achieve significant cost reductions, and shorten construction schedules.

With RTK piling, the coordinate data for pile locations specified in the design drawings are used directly on site. Using a high-precision GNSS receiver (RTK-capable device), workers can check in real time on site the offset between their current position and the target position where the pile should be installed. For example, if you use an RTK receiver connected to a smartphone, the screen can display instructions such as "5 cm east, 10 cm north to the target point," allowing you to reach the exact position by moving only a few steps as directed. This makes it possible to complete pile positioning work — which conventionally required repeated measurements by an experienced surveyor and assistants — easily and quickly by a single person.

Compared with conventional manual piling surveying techniques, RTK piling’s major difference is that digital technology automates and refines positioning. In the flow of i-Construction and construction DX promoted by the Ministry of Land, Infrastructure, Transport and Tourism, the movement to introduce such cutting-edge positioning technologies on sites is accelerating. With labor shortages worsening, RTK piling is expected to contribute to improved on-site productivity by enabling accurate and rapid work with fewer personnel.

Issues with conventional piling work

To understand the benefits of RTK piling, first let’s organize the problems inherent in traditional piling (positioning) work. Conventional methods centered on manual surveying teams had the following issues.

• Multiple personnel required: Placing pile positions normally requires two people working as a pair (one operating the survey instrument and one holding a staff rod or tape measure). On large sites, surveying may be done with three or more people including assistants, which is labor-intensive.

• Time-consuming work: Because surveying equipment (total stations or tape measures) must be set up and positions confirmed repeatedly while placing piles, on sites with many piles the positioning work alone can often take an entire day or more. When surveying wide areas, time spent moving the team around the site also accumulates, making it hard to raise efficiency.

• Risk of human error: Manual surveying and marking are subject to human mistakes. Mistyping measured values or misplacing marks can lead to piles being driven in the wrong locations. If errors are discovered later, rework or repairs may be needed, resulting in extra time and cost.

• Dependence on skilled personnel: Operating surveying equipment and achieving accurate pile positioning require experience, leading to reliance on specific experienced surveyors. If a skilled worker is occupied elsewhere or absent, the site could be delayed waiting for surveying. With an aging workforce and a shortage of young technicians, this dependence on individuals is a major problem.

• Constraints due to environment and time of day: Optical surveying (total stations, etc.) requires line-of-sight between the instrument and the staff, so in sites with many obstacles in the terrain or in poor-visibility conditions such as at night or in thick fog, maintaining accuracy is difficult and efficiency declines. Susceptibility to weather and time-of-day conditions is another weakness of traditional methods.

As described above, traditional piling work tends to require a lot of manpower and time to ensure accuracy, making it inefficient. This not only leads to increased labor costs and longer construction periods but also creates risks to quality and schedules due to rework caused by mistakes.

Benefits brought by RTK piling

Given these challenges, let’s look at the benefits of introducing RTK piling. Digitalization and automation through RTK technology can deliver dramatic effects such as the following.

• Significant labor cost reduction: The greatest advantage of RTK piling is cost reduction through reduced manpower. If pile positioning work that previously required two to three people can be completed by one person, labor costs can be cut to less than half by simple calculation. For example, on one site, installation of survey stakes that used to take two people a full day was completed by one person in a few hours after RTK was introduced. In that case, work time was reduced by more than 70%, and labor costs were significantly compressed. In the context of labor shortages, simply reducing the required number of personnel is highly valuable. Furthermore, if pile setting that was previously outsourced to surveying companies can be handled by in-house staff, outsourcing costs can be reduced and total costs lowered.

• Shortened construction period: Dramatic improvements in efficiency directly translate into shorter construction times. RTK pile positioning simplifies the positioning steps and smooths movement, so the number of piles that can be processed in a day increases substantially. In fact, an example using a GNSS + AR piling system reported that work time improved to about one-sixth of conventional optical surveying methods (about an 83% reduction). In one road construction case, stake installation that used to take half a day was completed in under an hour, allowing follow-up processes to start earlier. Reducing wait times due to pile positioning provides leeway in the overall site schedule. As a result, project-wide schedule compression can be achieved, leading to secondary effects such as higher client satisfaction from early completion and reduced indirect costs.

• Quality improvement due to high accuracy: RTK can achieve positioning accuracy of several centimeters, so even with fewer personnel, accuracy is not inferior to conventional methods. In fact, with digital measurement reducing human error, the accuracy and reliability of pile locations improve. Because positioning data can be shared and checked in real time on site, missed measurements and recording mistakes are quickly noticed. The risk of later discovery of position errors and subsequent rework is reduced, contributing to quality assurance and prevention of schedule loss.

• Improved safety: Reducing the number of personnel involved in surveying and piling minimizes the need to work near heavy machinery or enter high-risk or dangerous areas, lowering safety risks. With fewer required personnel and machine-guided work, the likelihood of contact accidents or fall accidents can be reduced.

As described above, RTK piling is an innovative method that delivers major benefits in both labor cost and construction period while ensuring quality. By saving labor and speeding up work, productivity increases, allowing more construction to be completed with limited resources. In fact, one-person operations using RTK have started to spread regionally; in disaster recovery sites some local governments used smartphone surveying to quickly survey damaged areas with a small team, advance the start of recovery work, and achieve substantial cost reductions. These success stories show the significant impact RTK piling can have on sites.

Points for introducing RTK piling

Now, let’s explain the points you should be aware of when actually introducing RTK piling. When using new technology on site, paying attention to the following items will make the transition smoother.

• Prepare appropriate equipment and systems: RTK positioning requires a high-precision GNSS receiver and a surveying system (software) that can utilize it. You can rent or purchase conventional fixed RTK equipment, but recently ultra-compact RTK receivers that attach to smartphones or tablets have appeared. If you want to keep initial investment low, consider starting with such easy-to-use equipment. By using correction information services available nationwide in Japan (such as the Geospatial Information Authority’s Continuously Operating Reference Stations network or QZSS “Michibiki” CLAS), you can achieve centimeter precision without setting up your own base station.

• Ensure a good satellite reception environment: For stable GNSS positioning, a site with as much open sky as possible is preferable. In areas with canyon-like tall buildings or dense trees, satellite signals can be blocked and accuracy degrade. Depending on the site, take measures such as ensuring the best possible view of the sky or choosing time periods suitable for positioning. If using network RTK, make sure you are within a communication area and prepare a mobile router if needed.

• Prior operational training: Although modern RTK systems are often intuitive, it is important to practice thoroughly beforehand so you are not confused during actual site work. Not only the survey personnel but also the workers who will actually install piles should understand how to use the equipment and what the screen displays mean. Conduct an in-house pilot implementation to confirm the workflow and share procedures among site staff so operations will run smoothly on the day.

• Data linkage and accuracy management: Because RTK piling uses design drawing coordinate data directly, you need to prepare drawing data in the correct coordinate system in advance. If there is a discrepancy between public coordinates and local coordinates, apply corrections or transformations and align the device settings. It is also reassuring to verify positioning accuracy by using the conventional method in parallel for the first few piles to confirm system reliability. Store and share obtained data (such as as-built pile positions) digitally so they can be used for subsequent quality control and reporting.

If you prepare with the above points in mind, introducing RTK piling on site is not difficult. Once you start using it, its efficiency and high accuracy often lead people to say, "We can’t go back to the old way." Next, using the smartphone RTK system "LRTK"—which is increasingly being adopted—as an example, let’s look at the potential for simple surveying.

Simple surveying with LRTK

A solution that brings RTK technology within easy reach is the LRTK series by Reflexia. LRTK is an ultra-compact RTK-GNSS receiver that attaches to a smartphone or tablet; it weighs about 165 g and is about 1 cm thick (about 0.4 in), compact enough to fit in a pocket while providing centimeter-level positioning accuracy (cm-level accuracy (half-inch accuracy)). It connects to a smartphone via Bluetooth or cable and transforms the smartphone into a high-precision surveying device.

LRTK’s major advantage is that it combines ease of use with high accuracy. On-site preparation is simple and there is no need to set up large antennas or tripods. Attach the device to your phone, turn on the power, and launch the dedicated app, and RTK positioning begins in just a few dozen seconds. It supports correction signals from Japan’s quasi-zenith satellite "Michibiki" (CLAS), so even without a communications environment you can receive error correction information via satellite. Therefore, you can achieve positioning accuracy of a few centimeters (a few cm (approx. a few inches)) anywhere in Japan, maintaining stable accuracy even in mountainous or remote sites.

The dedicated app guides you in real time to the target point’s distance and direction based on pile position data imported from the design drawings. The app also overlays pile position markers on the smartphone camera view using AR (augmented reality), allowing you to intuitively identify the point where "the pile should be driven" while looking at the screen. Because it provides visual guidance rather than relying on a seasoned worker’s intuition, anyone can accurately place piles without hesitation. Reports from sites that adopted the LRTK system indicate that the time required for pile positioning was dramatically reduced compared with conventional methods and that follow-up corrections were almost eliminated. At a disaster recovery site, staff used smartphone surveying to quickly cover wide areas with limited personnel, accelerate the start of recovery planning, and achieve large cost reductions. In this way, LRTK makes one-person surveying and one-person piling realistic, and serves as a tool to drive a productivity revolution on site.

For those considering introducing RTK piling or simple surveying, LRTK is a strong option. Even without expensive dedicated equipment, LRTK alone enables high-precision surveying with just a smartphone. It is accessible for local governments and small-to-medium construction firms with limited personnel and budgets, and its benefits can be felt immediately after introduction. Use cutting-edge technology to promote DX on your site. Details and case studies of LRTK are published on the manufacturer’s official site, so check them if you are interested. The trend toward one-person operations using smartphone surveying will continue to expand and will likely become a new on-site standard in the future. Take this opportunity to adopt the latest technology on your site and realize cost reductions and shorter construction periods — you will likely experience a significant productivity improvement at your site!

FAQ

Q: What is RTK? A: RTK (Real-Time Kinematic) is a technology that achieves centimeter-level positioning accuracy by correcting GNSS positioning errors in real time. While conventional GPS positioning can have errors of several meters, RTK uses the difference between satellite signals received at a base station and a rover to instantly determine high-precision positions.

Q: What is the difference between RTK piling and conventional piling methods? A: The biggest difference is that the process of positioning and layout is digitalized and automated. Conventionally, surveyors used tape measures and total stations to calculate pile positions one by one, but RTK piling uses GNSS receivers to precisely determine the worker’s current position and navigate them to the designated pile locations. This enables pile positioning with fewer people and in less time, and reduces human error.

Q: What equipment and preparations are needed to introduce RTK piling? A: Basically, you need a high-precision RTK-capable GNSS receiver and a terminal (smartphone or tablet) and application to display and use the positioning data. In addition to fixed receivers, small attachable devices like LRTK are an option. You also need accurate design coordinate data and, depending on the situation, an internet connection if using network RTK. It is reassuring to become familiar with the equipment operation before introduction and to verify accuracy and procedures through trial operation.

Q: How much cost reduction and shortening of construction time can be achieved with RTK piling? A: Effects vary depending on site scale and conditions, but reductions in personnel and time are very large. For example, tasks that used to take two people a full day have become less than half a day for one person, and reports indicate labor cost reductions of over 50% and time reductions of 70–80%. In addition to labor cost savings, shortening the overall construction period can reduce management costs and indirect expenses.

Q: What kinds of sites and projects are suitable for RTK piling? A: RTK piling is basically effective for outdoor surveying and piling work. It is particularly effective for projects with many points over a wide area (road construction, land development, utility trenching, etc.) and disaster recovery sites requiring rapid response. It also provides significant labor-saving and time-saving benefits on small-to-medium projects with limited personnel and on sites where traditional surveying is time-consuming due to complex terrain. However, it cannot be used where GNSS signals cannot reach, such as inside tunnels or deep forest, so in those cases it must be used in combination with conventional methods.

Q: Does bad weather or site environment affect accuracy? A: RTK GNSS positioning does not suffer large accuracy degradation in rain or cloudy weather. However, if radio waves from satellites are blocked by buildings or trees, positioning can become unstable. In forests, urban canyons, or under overpasses, the number of receivable satellites decreases and accuracy may worsen or positioning may become impossible. In such environments, you may need to move temporarily to a place with an open sky to position, or use conventional methods such as total stations as a supplement.

Q: What is LRTK? A: LRTK is a product name for a small RTK-GNSS receiver that attaches to a smartphone. Designed to enable centimeter-level surveying easily for anyone in conjunction with a smartphone, it can receive dedicated correction information to achieve high-precision positioning throughout Japan. Compared with conventional large surveying equipment, it is inexpensive, highly portable, and simple to use, making it an attractive tool that supports one-person surveying and piling. It is relatively easy for first-time RTK adopters to handle, and its low introduction cost combined with tangible effects has been well received.