RTK Piling Dramatically Increases Construction Speed! Secrets to Improving On-site Productivity

Table of Contents

• What is RTK piling? Differences from conventional methods

• Why RTK piling increases construction speed and productivity

• Effects and benefits of introducing RTK piling

• Use cases of RTK piling and future prospects

• High-precision positioning starting with a smartphone: simple surveying with LRTK

• FAQ

Introduction

In the construction industry, improving on-site productivity has become an urgent issue as labor shortages and pressure to shorten construction schedules increase. Especially in civil engineering, the foundational task of "piling" requires both accuracy and efficiency. Conventional piling required extensive time and effort for surveying staff to stake out positions and set up batter boards. However, in recent years, the use of satellite positioning technology RTK (Real Time Kinematic) has advanced and brought revolutionary changes to the piling process. This aligns with the Ministry of Land, Infrastructure, Transport and Tourism’s promotion of *ICT construction* (i-Construction) and has attracted attention as a technology that supports digitalization on-site. By introducing RTK piling, construction speed can increase dramatically, leading to overall improvements in on-site productivity. This article explains the overview of piling using RTK, differences from conventional methods, specific effects and case studies, and a detailed look at the latest solution for simple surveying, “LRTK,” which can be considered a key to this transformation.

RTK technology is also being used in surveying and other construction processes beyond piling, and it is becoming an indispensable foundational technology on construction sites. Among these, piling is a field where RTK introduction yields particularly large effects and can be said to hold the key to improving on-site productivity.

What is RTK piling? Differences from conventional methods

First, let’s clarify what RTK piling is. Piling guidance refers to the surveying and guidance work to drive piles into the exact locations specified in design drawings for projects such as roadworks and bridge construction. Traditionally, survey personnel would use the coordinates on drawings and tools like measuring tapes or total stations (TS) to determine positions on site, mark the ground, and indicate pile locations. They installed pile markers or paint as reference marks for pile positions, and machine operators drove piles based on those marks. However, this conventional method required multiple people and took time for positioning and marking. Because the work was manual, there was a risk of mistakes in staking out survey points or marking, and any deviation could lead to re-driving piles (rework). In addition, in highly undulating terrain or low-visibility environments, visual guidance had limitations, making it difficult to place piles accurately.

The new method that solves these problems is piling using RTK technology. RTK is a technique for real-time, high-precision GNSS positioning that uses two receivers—a base station and a rover—to correct satellite signal errors and measure current position with accuracy within a few centimeters (within a few inches). Applying this RTK positioning to piling guidance allows pile locations to be identified and guided in real time with centimeter-level accuracy (half-inch-level accuracy) relative to design coordinates. Specifically, a terminal (controller) equipped with a GNSS receiver is mounted on the piling machine or carried by workers, who can check the deviation between their current position and the target pile position on a display while working. Because the direction and distance to the target point are displayed on the screen, the operator can intuitively know the “correct position,” and piles can be driven accurately without the detailed chalking/marking required in conventional methods. This enables both a significant reduction in surveying labor and a dramatic improvement in construction accuracy.

Why RTK piling increases construction speed and productivity

Why does introducing RTK piling significantly improve construction speed and on-site productivity? There are two main reasons.

The first is the reduction of time spent on surveying and staking out positions. With RTK, the task of calculating pile coordinates that previously took a survey team half a day to a full day can be completed in real time on site. For example, when installing reference piles for longitudinal and transverse control in roadworks, a process that used to require repeated measurements and take an entire day can be performed quickly and accurately with RTK-equipped devices. Dramatically reducing the time spent on surveying allows subsequent construction processes to begin the same day, shortening the overall construction period. In one verification, the introduction of ICT construction such as RTK and drone surveying reduced the number of days required for initial surveying from an average of 17.7 days to 2.7 days (approximately a 70% time reduction). Streamlining surveying processes consequently shortens the duration from start to completion.

The second is improved parallel work and personnel efficiency. RTK piling allows piling position identification that previously required two people to be performed by one person, greatly improving personnel allocation efficiency. Skilled surveyors no longer need to be constantly on site, allowing their labor to be directed to other important tasks. Because surveying related to piling is completed quickly with RTK, more tasks can be carried out in parallel. For example, time loss from idle heavy equipment waiting for surveying is reduced, increasing overall site utilization. Moreover, by reducing rework caused by mislocated piles, unnecessary redo work is eliminated, and total productivity increases. As some sites report that “after introducing RTK, sites previously swamped with surveying work now have leeway to spend time on quality and safety management,” RTK piling is a technology that can fundamentally change how work is conducted on site. Thus, introducing RTK piling can greatly reduce lost time from waiting for surveying and from rework, directly improving on-site productivity.

Effects and benefits of introducing RTK piling

Let’s organize the main effects and benefits that RTK piling brings.

• Improved construction accuracy and reduced rework: Real-time GNSS guidance allows piles to be driven into exact positions, greatly reducing surveying errors and installation mistakes. Consistently high-accuracy construction reduces the need for later corrections or pile re-drives, eliminating unnecessary rework.

• Shorter work time and reduced construction period: Surveying and marking processes are streamlined, dramatically reducing the time needed to calculate and verify pile points. The number of piles that can be processed per day increases, leading to a shorter overall project period. In one case, an AR-based piling system using GNSS reported a reduction in working time to about one-sixth of the conventional time.

• Cost reduction through reduced personnel and labor-saving: Pile positioning work that used to require 2–3 people can be completed by one person, reducing personnel costs. If marking work previously outsourced to external surveyors can be done in-house, outsourcing costs are also reduced. Fewer personnel around heavy equipment improves safety, achieving two benefits at once.

• Immediate use of survey data: Coordinates obtained with RTK, such as pile positions, can be recorded electronically on-site and shared/managed in the cloud. This reduces the effort of returning to the office to reflect measurements on drawings or organize reports, and if a measurement was missed on site it can be immediately remeasured, preventing later re-surveying. This contributes to improving efficiency across surveying to as-built management.

• Support for digital construction: RTK is a key technology for ICT construction promoted by the Ministry of Land, Infrastructure, Transport and Tourism, such as *i-Construction*. It is highly compatible with machine guidance and machine control based on 3D design data, and cases of batter-board-less construction (no temporary batter frames) are emerging. RTK piling contributes greatly as a foundation that advances on-site DX (digital transformation) while balancing productivity and quality control.

Use cases of RTK piling and future prospects

High-precision and efficient RTK piling is already being used in various sites. For example, in roadworks, introducing RTK guidance for piling along road centerlines and land boundaries has enabled placement of piles according to design alignment. There are reported cases where operators, without installing the temporary batter frames previously required for marking, used RTK guidance displays to perform excavation and embankment work up to the final roadway line. This is called batter-board-less construction, a good example of reducing surveying work while maintaining high-quality construction. Furthermore, in large-scale projects requiring many piles, such as dam construction or residential land development, RTK positioning allows operators to set pile positions sequentially while moving, vastly improving efficiency for wide-area piling work. In bridge construction as well, using RTK for pile driving at piers and bearing locations enables rapid surveying guidance under complex site conditions and helps prevent delays in the schedule.

Given these significant advantages, RTK piling is expected to become even more widespread. The background includes the industry-wide push for DX and the severe labor shortage. The government actively supports introducing ICT civil engineering technologies as productivity measures, and construction management using RTK-GNSS is likely to become standard. Recently, new technologies such as low-cost RTK receivers compatible with smartphones have lowered the barrier to adoption, further accelerating diffusion. As on-site RTK use becomes commonplace, processes that had stalled due to waiting for surveys or labor shortages will flow smoothly, greatly contributing to schedule adherence and cost reduction. If RTK systems that are intuitive for young engineers and machine operators increase, high-precision construction will be possible without relying on veterans, helping alleviate human resource shortages.

High-precision positioning starting with a smartphone: simple surveying with LRTK

For RTK to deliver maximum effect, it is important that it be a tool anyone can easily use. Attracting attention in this regard is the latest RTK solution for smartphones, “LRTK.” LRTK consists of an ultra-compact RTK-GNSS receiver that can be attached to a smartphone and a dedicated app, instantly transforming a handheld smartphone into a centimeter-accuracy surveying device. No large dedicated equipment or complicated cable connections are required, and positioning can start immediately upon arrival at the site; its intuitive operation and ease of use are appealing. For example, by attaching an LRTK device to a smartphone and connecting to a network-type RTK correction information service, high-precision positions can be obtained in real time on site. Models compatible with CLAS (centimeter-level positioning augmentation service; half-inch accuracy) can maintain high-precision positioning even at sites outside mobile communication coverage by receiving correction data directly from the QZSS “Michibiki” satellites. This enables stable surveying even at forested or mountainous construction sites where surveying was previously difficult.

Another innovative point is that smartphone-specific camera functions and AR (augmented reality) technology can be combined. Using one’s RTK position, a smartphone can overlay design lines or structural models onto the real-world view on the screen, so you can see “what will be built here” at a glance without looking at drawings. Without deciphering complex drawings or setting up temporary batter frames, simply pointing the smartphone allows accurate stakeout, enabling even inexperienced workers to identify surveying and piling points without mistakes. Smartphone RTK like LRTK opens high-precision positioning to more site staff and serves as a trump card for realizing simplified surveying that can be carried out by small teams. As a modern solution aligned with the Ministry’s *i-Construction* initiatives, it will strongly promote on-site DX from surveying to construction management. If you are considering labor-saving and efficiency improvements using RTK, consider introducing smart surveying with LRTK.

FAQ

Q: How accurate is RTK positioning? Is it comparable to optical surveying like total stations? A: RTK-GNSS can achieve about 1–3 cm (0.4–1.2 in) horizontal accuracy and about 3 cm (1.2 in) vertical accuracy in open-sky environments. While it is not as precise as the millimeter-level accuracy obtainable with total stations, this level of accuracy is adequate for many civil surveying and construction management tasks. Moreover, because RTK can survey large areas at once and does not accumulate errors between control points (global positioning), it can deliver practically comparable results. However, in environments with tall buildings or trees nearby, reflections or signal blockage can degrade accuracy, so it is preferable to perform RTK surveying in as open a sky area as possible.

Q: Do you need special qualifications or advanced skills to use RTK surveying? Can one person operate it? A: No special national qualification is required for RTK surveying itself. If you understand basic equipment operation and the principles of positioning, non-surveyors can use it. RTK, by principle, allows one-person operation for surveying and piling. There is no need for an assistant to hold a prism at the survey point as with a total station; operators simply follow the guidance displayed on a smartphone or tablet screen, so advanced skill is not required. However, some knowledge of geodetic/datums and coordinate systems is necessary to judge the reliability of obtained coordinates and reflect results on drawings. Also, when producing official survey deliverables, it is still advisable to perform work under the supervision of a qualified person (such as a licensed surveyor), as with conventional methods.

Q: Can RTK surveying be used at sites without network coverage, such as mountainous areas? A: Yes, it can. Typically, network RTK positioning has the rover receive base station data (corrections) via mobile communications, but in areas without mobile coverage, you can use the QZSS “Michibiki” centimeter-level augmentation service (CLAS). With a CLAS-compatible RTK receiver, high-precision positioning can be maintained using satellite-delivered corrections without relying on communication infrastructure. However, in dense forests or places where receiving satellites themselves is difficult, RTK solutions may not be obtainable. In such cases, a combined approach using conventional methods—e.g., temporarily moving to an open area to get a fix and then transmitting coordinates by relative surveying—may be necessary.

Q: I’m concerned about the cost of introducing RTK equipment. Is it cost-effective? A: There is an initial cost, but the efficiency gains often make the investment worthwhile. For example, if surveying that used to take two people a full day can be completed by one person in a few hours with RTK, labor cost savings are substantial. Recently, low-cost smartphone-compatible RTK receivers and subscription-based correction services have appeared, making high-precision positioning available without the large capital expenditures of the past. Considering productivity improvements and labor savings on-site, RTK introduction can often pay for itself.

Q: If we have RTK, are total stations or levels no longer necessary? A: RTK streamlines many surveying tasks, but optical surveying instruments remain useful in some conditions. For example, in tunnels or building interiors where satellite signals do not reach, total stations and levels are still indispensable. Also, for short-range tasks requiring millimeter-level accuracy such as precise leveling or equipment installation measurements, optical instruments may be more reliable than RTK. Therefore, rather than replacing all existing instruments after introducing RTK, it is wise to use RTK for wide-area outdoor surveying and complement it with TS and levels where high precision is required. Using both appropriately will balance overall surveying productivity and accuracy.

Q: Can RTK positioning be performed in rain or at night without problems? A: Basically, RTK-GNSS positioning is available 24 hours regardless of weather or day/night. Rain and clouds have minimal impact on satellite signals, and as long as line-of-sight to the sky is maintained, accuracy is not greatly affected. However, heavy rain causing water droplets to accumulate on antennas or ionospheric effects from thunderclouds can temporarily destabilize accuracy. In such cases, it is safer to pause work and wait for better conditions. Unlike optical instruments, darkness does not hinder GNSS positioning, so accurate surveying and piling can be performed at night when necessary. Even during night work, however, ensuring site safety and visibility remains as important as during daytime.