High-cost equipment no longer necessary? Dramatically reducing civil engineering surveying costs with smartphone-compatible high-precision GPS terminal LRTK

Introduction

In civil engineering and construction sites, centimeter-level high-precision surveying is indispensable to ensure construction is carried out according to design drawings. However, achieving that high precision has traditionally required expensive dedicated equipment (such as total stations and surveying GPS receivers) and skilled technicians, which has been a heavy burden for small and medium-sized construction companies and local governments. Costs for purchasing and maintaining equipment and labor costs for specialists have accumulated, posing a major challenge in an industry that needs efficiency improvements and cost reductions.

Recently, a new solution that addresses this challenge— the smartphone-compatible high-precision GPS positioning terminal "LRTK"—has been attracting attention. This innovative technology enables centimeter-level positioning with the ease of use of a smartphone, allowing anyone with a phone to significantly reduce surveying costs. In this article, we review the traditional cost issues in surveying, explain the mechanism and functions of LRTK, show real-world use cases, discuss the benefits of adoption, and look at future prospects. We introduce the capabilities of this cutting-edge surveying technology that may render expensive equipment unnecessary.

Cost issues in traditional civil surveying

The precision required for civil surveying is extremely high; even deviations of a few centimeters are unacceptable. However, the accuracy of general GPS (the positioning functions embedded in car navigation systems and smartphones) is roughly 5–20 m (16.4–65.6 ft), which is far too large to be used for construction surveying. Therefore, dedicated expensive surveying equipment such as total stations that use light waves and high-precision GNSS receivers have been indispensable on site. These devices often cost several million yen to purchase, and ongoing expenses for rental and maintenance add recurring costs.

Furthermore, operating conventional surveying equipment requires the skills of experienced surveyors, and tasks typically require two or more personnel. For example, with a total station one person must set up the instrument while another holds a staff at the survey point, and such teamwork is essential. For large-area surveys, frequent instrument relocations and ensuring line-of-sight are time-consuming, making tasks long. The increases in labor costs and working hours have become a severe burden for the construction industry, which already suffers from chronic labor shortages.

In short, the cost of ensuring high precision has always been an issue in civil surveying. The dual hurdles of investing in and maintaining expensive equipment and securing specialist personnel have stood in the way of DX (digital transformation) for small and medium construction companies and local governments.

Overview of LRTK and how it reduces costs

LRTK is an ultra-compact RTK-GNSS receiver that attaches to a smartphone or tablet. It is a pocket-sized terminal weighing only about 125 g and approximately 13 mm (0.51 in) thick, with a built-in battery and high-performance antenna, and can be carried easily in one hand. It can be attached to a dedicated smartphone case with one touch, and when necessary it can be mounted on the included pole or tripod for fixed-point positioning. This single device serves as a versatile surveying tool capable of meeting a wide range of surveying needs, from high-precision positioning to 3D scanning and AR-based position display.

The mechanism by which LRTK achieves centimeter-level positioning is based on RTK (real-time kinematic) satellite positioning technology. Via a smartphone it connects to the Geospatial Information Authority of Japan’s Continuously Operating Reference Station network and private correction information services, receiving GNSS error correction data from reference stations in real time. At the same time, the LRTK terminal itself receives signals from multiple satellite constellations such as GPS, GLONASS, and Michibiki, and positioning calculations are performed in a dedicated smartphone app. This reduces errors that were several meters in standalone positioning down to a few centimeters. The latest LRTK models support multiple frequency bands for greater positioning stability and can receive the centimeter-level augmentation service (CLAS) broadcast by Japan’s quasi-zenith satellite system Michibiki. This allows high-precision positioning even in mountainous areas or disaster sites where cellular coverage is unavailable, enabling positioning without an Internet connection and reducing the labor and costs that used to be required for setting up base stations or post-processing.

These technical innovations enable LRTK to deliver dramatic cost reductions. By leveraging the smartphone’s display, communications, and processing capabilities, the need for dedicated equipment is minimized and initial deployment costs are set far lower than conventional instruments. Because it can be used with a smartphone on hand, there is no need to acquire additional expensive equipment. Its simple operation allows a single person to complete surveying tasks, directly reducing labor costs. Tasks that previously required multiple people and long hours can be completed in less time with fewer staff, making a “one device per person” deployment realistic. Small firms that used to share a limited number of instruments across sites can now have each worker conduct their own surveys, improving productivity and preventing lost opportunities. In short, LRTK aims to overturn conventional wisdom by enabling high-precision surveying that is “easy for anyone, anywhere, and affordable.”

Main functions of LRTK

• Centimeter-level high-precision positioning: Multi-GNSS support and RTK methods consistently achieve positioning accuracies of a few centimeters. Even across large sites, survey points can be acquired accurately, making it easy to secure the high precision necessary for construction management in accordance with design drawings.

• Smartphone integration and dedicated app: A dedicated surveying app that runs on a smartphone allows anyone to use the system without difficult operations. Tasks such as coordinate system conversion, drawing of observed data, and input of point names are automated, enabling data measured on site to be immediately reflected in plans and numerical outputs.

• 3D point cloud scanning support: In conjunction with the smartphone’s camera and sensors, users can walk around and rapidly scan surrounding structures and terrain to obtain high-density 3D point cloud data. Measurements are possible up to approximately 60 m (196.9 ft) away, and all acquired point clouds are assigned accurate coordinates. Outputs compliant with the Ministry of Land, Infrastructure, Transport and Tourism’s "Guidelines for As-Built Management" can be produced, so this point cloud data can be submitted as official as-built deliverables.

• Positioning possible even outside communication coverage: Supporting Japan’s satellite positioning augmentation service (CLAS), LRTK can perform real-time centimeter-level positioning even in mountainous or radio-coverage dead zones. This permits continued high-precision surveying at isolated post-disaster sites or in environments without communication infrastructure (where previously post-processing in the office or special wireless setups were necessary).

• AR guidance and visualization: Design drawings and measured point clouds can be overlaid on the actual site scenery using AR. Thanks to LRTK’s high-precision positioning, objects displayed in AR do not shift, allowing virtual models to be placed at true-to-scale positions. This can be used to intuitively indicate pile-driving or structure installation positions on site, or to visualize buried infrastructure such as pipes. It is also effective as a tool for sharing completion images between clients and contractors.

• Cloud sync and data sharing: All data obtained through surveying can be synced and saved to the cloud with one touch. Information can be shared in real time with office PCs via the Internet, allowing stakeholders to review geotagged photos, point cloud models, and measurement results on the spot. By issuing a shareable link, clients or other departments without dedicated software can view data through a browser. The ability to utilize survey data on handheld devices without expensive dedicated software or high-performance PCs is another advantage.

Use cases for LRTK

Slope surveying

Surveying the shapes of steep slopes and embankments/cuts has traditionally been fraught with danger. Surveyors would climb slopes to set staffs or take multiple measurements from a distance with a total station, a process that required time and manpower. With LRTK, one can simply walk while observing the slope from a safe, distant position to obtain the entire slope’s shape as a 3D point cloud. Because there is no need to climb to high locations and detailed terrain information can be obtained in a short time, both safety and efficiency of operations are dramatically improved. From the acquired point cloud, slope angles, surface areas, and cut/fill volumes can be calculated automatically, enabling immediate checks of stable slopes and soil quantity estimations on site.

Disaster response

At disaster sites such as landslides or earthquakes, rapid situation assessment and restoration planning are required. LRTK enables survey of the topography of affected areas without bringing in heavy or large equipment. Even in mountainous regions where communications are cut off, satellite augmentation signals can be used to generate maps and terrain models of the damage area in real time. The compact equipment allows surveyors to enter narrow collapse zones to take measurements and exit quickly, and the high-precision data obtained can be shared with headquarters via the cloud to solicit remote guidance or support rapid decision-making.

As-built management

LRTK is also powerful for as-built surveying after construction completion. Scanning completed structures or developed sites with LRTK yields 3D as-built surface data on site. By overlaying the design model and acquired point cloud in the dedicated app, it is immediately apparent whether the finished work matches the design. Areas with deviations are color-coded, so locations requiring correction are not overlooked. This prevents rework while ensuring quality, and streamlines the creation of as-built management documents. Processes that previously required site inspection followed by office drafting are substantially shortened, contributing to reduced time to project completion, including preparation of inspection documents.

On-site visualization with AR

Combining LRTK with AR technology makes it possible to intuitively visualize design data on site. For example, AR display of a planned structure on a preconstruction site allows checking of interfaces with surrounding elements and appearance in advance. During construction, projecting design reference lines and elevation information onto the site helps workers identify installation positions without referring to drawings. AR aligned with LRTK’s cm-level accuracy (half-inch accuracy) does not drift even after long walks, so it can be used reliably on large sites. This enables accurate construction without relying on the intuition of veterans, helping to prevent variability in quality.

Remote sharing via cloud integration

With cloud integration, data obtained on site can be shared instantly internally and externally, enabling remote project support. Because surveying data and site photos are uploaded to the cloud in real time, engineers in the office and clients can grasp the latest site conditions. This allows expert input to be reflected quickly in on-site decision-making and facilitates prompt issuance of design change instructions. Accumulating daily progress data in the cloud makes pre-checks for as-built inspections and root-cause analysis in case issues are found easier. Sharing information across physical distances helps prevent unnecessary rework and reduces communication losses.

Benefits of adoption

• Reduced work time: Time spent on surveying preparation/cleanup, inspections, and drafting is greatly reduced. Eliminating complex equipment setup and line-of-sight procedures speeds up the process from on-site measurement to data submission. Real-time data sharing and analysis accelerate decision-making and contribute to shorter construction periods.

• Reduced labor costs: Because one person can conduct surveys efficiently, required personnel can be reduced, leading to labor cost savings and allowing surveying tasks to be handled even at sites with labor shortages. If tasks previously outsourced to specialized surveying firms can be handled in-house, outsourcing costs can also be reduced.

• Improved safety: Compact, lightweight equipment reduces the need for workers to remain for long periods in hazardous areas, contributing to worker safety. Surveying in risky locations such as slopes or disaster sites can be conducted safely from a distance. Reduced burden of moving equipment lowers the risk of accidents in high places or on poor roads.

• Reduced training burden: Intuitive smartphone apps shorten the time required to become proficient. They are easy for young or novice staff to use, reducing the time and cost of in-house training. This allows surveying operations to be carried out without relying on particular veterans, preventing tasks from becoming person-dependent.

Future prospects

Smartphone-integrated surveying technologies represented by LRTK are expected to become increasingly widespread. The Ministry of Land, Infrastructure, Transport and Tourism’s promotion of *i-Construction* will be a tailwind, and high-precision GNSS terminals will likely become standard equipment as tools that support site digitalization and labor savings. Against the backdrop of chronic workforce shortages in the construction industry, movements to streamline site operations through “one device per person” surveying devices are accelerating. As surveying tasks that were once the domain of specialists become accessible to anyone, the challenge of skill succession across generations should become easier to overcome.

Technologically, advances in satellite positioning systems and improvements in mobile device performance will further enhance the accuracy and reliability of devices like LRTK. In the future, integration with wearable devices such as AR glasses and combinations with AI-based automatic analysis are expected to further expand the range of surveying data applications. With compact equipment and the power of the cloud, surveying and measurement tasks that previously required large machines and many personnel will soon be performable with ease. LRTK can be seen as a precursor to this emerging new era of surveying practices that are becoming the new norm.

Conclusion

In a field that until now depended on expensive equipment and specialist technicians, LRTK offers a new option: simple surveying with a smartphone. This solution, which maintains centimeter-level precision while greatly reducing cost and effort, will demonstrate practicality and reliability across a wide range of sites, from small and medium construction companies to local governments. Actual adoption of LRTK can reduce the time and personnel previously devoted to surveying, freeing those resources for other important tasks.

Whether expensive equipment will truly become “no longer necessary”—the answer will become clear once LRTK is used on site. The groundbreaking approach of high-precision surveying that can be started with a single smartphone is expected to lower the bar for surveying work and contribute to productivity improvements across the industry. Sites struggling with costs have an excellent opportunity to adopt LRTK’s easy and high-precision surveying. Actively embrace the latest technology and evolve civil surveying into something smarter and more efficient.