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RTK Surveying Challenges on Civil Engineering Sites and Solutions with the LRTK Device

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Published March 13, 2025

To make on-site surveying more efficient and accurate, RTK surveying is the technology that meets the needs of the construction industry. RTK (Real-Time Kinematic) GPS positioning is a groundbreaking method that allows for high-precision location identification with errors as small as a few centimeters.
It is increasingly being utilized in a wide range of fields, including construction surveying, infrastructure maintenance, and civil engineering.
However, a challenge arises in environments such as mountainous areas, tunnels, and disaster sites, where RTK surveying cannot be effectively used due to lack of communication coverage. This article provides a detailed explanation of the basics and importance of RTK surveying, the challenges it faces, and the solution with the high-precision positioning device "LRTK," which works even in areas without communication coverage.
The Basics and Importance of RTK Surveying
What is RTK surveying? RTK (Real-Time Kinematic) positioning is a technology that achieves centimeter-level positioning accuracy by applying real-time correction data from a base station to the positioning information obtained from GNSS (Global Navigation Satellite System). Typically, standalone GPS positioning results in errors of about 5 to 10 meters, but RTK surveying can reduce this error to just a few centimeters, making it highly effective for civil engineering surveying tasks that require precise positioning, such as accurate placement of structures and as-built management.
For example, compared to traditional surveying using a total station, RTK-GNSS surveying allows for the measurement of a wide range of points in a short amount of time, significantly reducing personnel and effort.
In practice, the introduction of RTK has drastically increased the productivity of surveying work and has become an essential technology in promoting the digital transformation (DX) of construction sites. In recent years, high-precision positioning has also been required for drone surveying, machine guidance, and the creation of digital twins on-site, and RTK positioning has become the foundational technology supporting such cutting-edge construction management.
Challenges of RTK Surveying on Civil Engineering Sites (Issues in Off-Network Environments)
While RTK surveying is highly accurate and convenient, it is important to note that it relies on communication infrastructure. By its nature, RTK requires a communication method to transmit correction information from the base station (reference point) to the rover (mobile unit). Typically, correction data is received via wireless communication or the internet (such as Ntrip services over mobile networks), but in areas with no mobile signal, such as mountainous regions or tunnels, this communication cannot be established. As a result, RTK surveying will only achieve the same accuracy as standard GPS positioning.
In environments where network-based RTK cannot be used, one option is to set up a base station and communicate via radio signals. However, this requires the transportation and setup of base station equipment, as well as configuring communication settings. Especially in disaster response scenarios, it is often impossible to bring in large equipment, and there are cases where mobile phone base stations collapse or power outages prevent internet access. In fact, during the Noto Peninsula earthquake, communication infrastructure was severed, making traditional RTK surveying extremely difficult. In off-network environments, the need to switch to manual surveying methods and forgo high-precision positioning often leads to a decline in both work efficiency and accuracy.
Thus, the challenge of "RTK not being usable in off-network environments" is a widespread issue affecting many sites, from large construction companies to small civil engineering contractors and infrastructure maintenance personnel. So, is there a reliable positioning method that can be used confidently in off-network environments? This is where the LRTK device, introduced below, comes in.
What is the LRTK Device? A High-Precision Positioning Technology That Works Even in Off-Network Environments
The LRTK Phone is an ultra-compact GNSS receiver with an integrated antenna and battery. By attaching it to a smartphone, it can receive the CLAS signal from Michibiki (Japan's Quasi-Zenith Satellite System), enabling centimeter-level high-precision positioning even in areas without internet connectivity.
The LRTK Phone is a pocket-sized device, weighing approximately 125g and with a thickness of 13mm, which includes an integrated battery. When combined with a smartphone, it functions as an all-in-one versatile surveying tool for use on-site.
Using the dedicated smartphone app, it is possible to take photos with high-precision location information and acquire 3D point cloud data. The positioning data can also be instantly shared and managed in the cloud. Compared to traditional large GNSS surveying equipment, the price is very reasonable, making it realistic for each worker to carry one device.
The key technology is CLAS (Centimeter-level Augmentation Service) provided by Michibiki. With an LRTK device supporting CLAS, you can receive satellite signals with augmentation information calculated by the Ministry of Land, Infrastructure, Transport and Tourism’s electronic reference point network, allowing real-time positioning with centimeter-level accuracy. This means no base station or communication line is required, and as long as the sky is visible, high-precision positioning can be achieved anywhere in Japan.
While initial convergence may take slightly longer compared to traditional RTK, the accuracy of a few centimeters in the horizontal direction is sufficient for civil engineering surveying applications. The LRTK device supports multiple satellite systems, including GPS, GLONASS, and Galileo, as well as multiple frequency bands (L1/L2/L5/L6). It is equipped with high technical specifications that ensure stable positioning even in environments where satellite visibility is limited, such as mountainous areas.
In summary, the LRTK device is an "RTK surveying tool that works even in off-network environments." The big advantage, compared to traditional systems, is that with just a smartphone, high-precision surveying with centimeter-level accuracy can begin immediately on-site without the need for time-consuming setup or adjustments. In the next section, we will take a closer look at the main features of this LRTK device.
Features and Solutions of the LRTK Device (Michibiki CLAS Support, Low Power Consumption, Portability)
The reason the LRTK device can overcome the challenges of off-network environments lies in its excellent design and functionality. Here, we will outline the key features of this product.
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Michibiki CLAS Support – Centimeter-Level Positioning Without Communication:
As mentioned in the previous section, the LRTK device directly receives the CLAS signal from Japan’s Quasi-Zenith Satellite System (Michibiki) to obtain correction data. This allows for centimeter-level high-precision positioning in areas where mobile phone signals or wireless communications are unavailable. Because it does not rely on communication infrastructure, surveying can continue even in situations where internet connections are blocked during disasters or in remote areas where setting up a base station is difficult. The ability to eliminate the need for “communication” or “base stations” itself is a key point that will transform the way RTK surveying is conducted on civil engineering sites. -
Low Power Consumption for Long Operation Times:
The LRTK device excels in power-saving design. With its built-in battery, it can operate continuously for over 12 hours, making it more than sufficient for a full day of surveying from morning to evening. Unlike traditional GNSS receivers, which may require external power sources or large batteries, the LRTK device can be used wirelessly throughout the day with just a single charge. Its low power consumption makes it ideal for environments where securing power is difficult, such as remote areas, and ensures reliability even during long observation periods. -
Compact, Lightweight, and Excellent Portability:
One of the LRTK device's biggest features is its compactness and ease of use. With a small size that fits in the palm of your hand and weighing just a few hundred grams (125g for the LRTK Phone), it is lightweight, allowing workers to carry it at all times and "take measurements quickly when needed." The convenience of being able to take measurements by simply holding the receiver integrated with the smartphone, without the need for a dedicated pole or tripod, is revolutionary. Its design also considers environmental durability, such as dustproof and waterproof capabilities, making it reliable in harsh construction site conditions. Unlike traditional stationary GPS equipment, it does not become burdensome during surveys that involve working in tight spaces, on high locations, or long-distance walking. Additionally, it can be mounted on a dedicated monopod or pole to conduct surveying in the same way as traditional methods, offering flexible usage depending on the situation.
Due to these features, the LRTK device excels in situations where traditional RTK surveying devices struggle, such as "off-network environments," "difficulty securing power," and "mobility requirements." Let’s now take a look at how LRTK can be utilized on-site in specific scenarios.
Specific Surveying Scenarios with LRTK (Mountainous Areas, Tunnels, Disaster Sites)
The LRTK device, with its portability and no need for communication infrastructure, can be used effectively in various environments where RTK positioning was previously difficult. Below, we introduce several key scenarios where LRTK proves its worth.
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Remote Area Surveying in Mountainous Regions:
In locations like dam construction sites in the mountains or roadwork in forested areas where mobile signals are unavailable, LRTK excels. In environments where base stations were previously required or post-processing was necessary, workers can simply carry an LRTK-equipped smartphone and instantly perform high-precision positioning on-site. As long as the sky is visible, direct correction signals from satellites can be received, enabling RTK-equivalent accuracy even in remote surveying areas. With LRTK, you can now perform planned surveys and as-built checks in real-time, even in places where "off-network" was previously an obstacle. -
Positioning in Tunnels and Underground Spaces:
In tunnels and underground facilities, GNSS signals are typically blocked, presenting a fundamental challenge. However, with LRTK's portability and functionality, this issue can be partially resolved. For example, high-precision positioning can be established at visible points near tunnel entrances or shafts, and this reference can be used to continue surveying inside the tunnel. Once accurate coordinates are set using the LRTK device and smartphone, traditional total stations and other methods can be combined for surveying inside. This ensures that high-precision measurements are maintained even in environments where connectivity to the outside is cut off. Additionally, the LRTK app includes an indoor positioning mode, which allows surveying to continue even in places where GNSS signals cannot be received, such as under bridges or short tunnel sections. -
Rapid Situation Assessment in Disaster Sites:
In disaster-stricken areas immediately after a large-scale disaster, infrastructure may be severed, making surveying difficult. However, accurately and quickly recording and sharing the damage is crucial for planning recovery. This is where the off-network LRTK device truly shines. When surveyors bring LRTK devices into disaster areas with downed communication networks, they can measure the location of damage with centimeter-level precision and record it alongside photos and notes. For example, during the Noto Peninsula earthquake, LRTK played a critical role by successfully collecting and sharing high-precision location information from collapsed areas despite communication being cut off. In disaster response, time is critical, and the ability to share data instantly via the cloud with headquarters or relevant organizations proves highly valuable. Having just one small LRTK device can significantly enhance the speed and efficiency of situation-sharing on-site.
Additionally, the LRTK device can be applied to infrastructure maintenance tasks.
For example, in concrete structure crack inspections, the inspector can take photos with a smartphone and automatically tag them with the precise coordinates obtained via LRTK, saving them to the cloud.
This approach digitizes inspection records, which were previously cross-checked with paper drawings, and allows photos and location data to be shared seamlessly. As a result, report creation and tracking of deterioration are significantly more efficient. For infrastructure inspections, such as those for JR or highways, carrying an LRTK device allows for immediate recording of the coordinates of any abnormalities, which can be helpful in planning repairs.
Dramatically Improve Surveying Accuracy and Work Efficiency on Site with LRTK
The LRTK series enables high-precision GNSS positioning in the fields of construction, civil engineering, and surveying, allowing for significant reductions in work time and major improvements in productivity. It is also compatible with i-Construction, a program promoted by the Ministry of Land, Infrastructure, Transport, and Tourism, making it the ideal solution for advancing digitalization in the construction industry.
For more details on LRTK, please visit the following links:
For any inquiries about the product, quotes, or consultations regarding implementation, feel free to contact us through the inquiry form below. Let LRTK help take your site to the next level.