Table of Contents

• Basics of high-precision positioning and its expanding use in construction sites

• Use cases of high-precision positioning at construction sites (as-built verification, layout marking, pile center guidance, structure installation, exterior works)

• Use of latest technologies such as AR navigation and point-cloud comparison

• Efficiency, safety, repeatability, and labor savings brought by improved positioning accuracy

• Easy high-precision positioning and operational benefits with smartphones × GNSS × AR

• Implementation steps for the smartphone GNSS device “LRTK”

• Conclusion: Start high-precision positioning with LRTK

In recent years, the construction industry has paid growing attention to high-precision positioning technologies. Traditionally, surveying and staking out on civil engineering and construction sites relied heavily on specialized surveying instruments and skilled technicians, making efficiency a challenge. However, with the advent of GNSS (Global Navigation Satellite Systems)–based Real-Time Kinematic (RTK) positioning and QZSS’s centimeter-level positioning augmentation service (CLAS), centimeter-level positioning on-site is becoming increasingly accessible. Also, within the ICT construction trends promoted by the Ministry of Land, Infrastructure, Transport and Tourism such as “i-Construction,” these high-precision positioning technologies are rapidly spreading as key tools for improving productivity and quality control.

This article outlines the fundamentals of high-precision positioning and trends in its adoption on construction sites, and introduces practical on-site use cases. It also touches on recent technology applications such as AR (augmented reality) navigation and point-cloud data use, and examines effects like efficiency gains, improved safety, repeatability, and labor savings that come with better positioning accuracy. Special attention is given to easy high-precision positioning solutions that combine smartphones and GNSS devices, and as a concrete example, we explain implementation steps for simple surveying and AR construction using the smartphone GNSS device LRTK. We hope this provides useful insights and tips for site managers considering adopting high-precision positioning.

Basics of high-precision positioning and its expanding use in construction sites

High-precision positioning refers to techniques that add various corrections to position information obtained from GNSS satellites to determine position with errors reduced to on the order of a few centimeters. Standard GPS-based positioning can have errors of several meters (several ft), but the RTK (Real-Time Kinematic) method achieves centimeter-level (half-inch accuracy) high-precision positioning in real time by simultaneously receiving GNSS signals at two points—the base station and the rover—and correcting the relative error with respect to the base station. Traditionally, RTK positioning required the rover to receive correction information from a base station via radio or the Internet, but recently network RTK (correction distribution services from base station networks) using mobile communication networks has been established, making high-precision positioning easy to use anywhere nationwide.

In Japan, the start of the QZSS-provided CLAS is particularly noteworthy. CLAS is a free high-precision positioning augmentation signal transmitted directly from QZSS satellites; with a compatible receiver, centimeter-level (half-inch accuracy) positioning is possible even in areas without Internet coverage, such as mountainous regions (for details, see the [official Michibiki site explanation](https://qzss.go.jp/overview/services/sv06_clas.html)). This enables real-time acquisition of high-precision position information at sites where it was previously difficult to secure base stations or communications (e.g., mountain construction sites or disaster sites).

With these technical advances, the use of high-precision positioning on construction sites has greatly expanded in recent years. The Ministry of Land, Infrastructure, Transport and Tourism promotes ICT earthworks and other *ICT construction*, and in sites using 3D design data for construction and as-built management, adoption of high-precision GNSS equipment is progressing. While total stations and optical surveying instruments like levels were traditionally central, GNSS surveying equipment is increasingly used for quick surveying and stakeout in open sites. Moreover, not only large construction firms but also small and medium-sized contractors and local governments are increasingly using relatively low-cost high-precision GNSS receivers and correction services for in-house surveying. Recently, solutions that combine smartphones or tablets with compact GNSS receivers have emerged, making centimeter-class positioning accessible to anyone on site without special dedicated instruments.

Use cases of high-precision positioning at construction sites

High-precision positioning technologies are used across a variety of construction and civil engineering site tasks. Here are five representative use cases: as-built verification, layout marking, pile-center guidance, structure installation, and exterior works.

As-built verification

As-built verification is the process of confirming whether the terrain or structures after construction match the design shapes and dimensions. Using high-precision positioning, you can immediately measure the elevation and slope of completed embankments or pavements on site and compare them with design data. For example, surveying machines equipped with RTK-GNSS receivers can survey large areas quickly, and the acquired coordinate data can be instantly checked against 3D design models for as-built inspection. For point-cloud data obtained from drone photogrammetry or iPad LiDAR scans, providing accurate position coordinates via GNSS positioning enables as-built measurements without misalignment. This makes it easier to identify areas requiring rework on the spot, contributing to quality assurance and schedule reduction.

Layout marking

Layout marking indicates lines and points on the ground or structures that serve as construction references. Traditionally, positions were set using drawings and tape measures or total stations, but using high-precision GNSS greatly improves efficiency. By plotting coordinates from design drawings on-site with a tablet equipped with a GNSS receiver, layout marking can be performed flexibly across large sites without being tied to survey control points. For example, land subdivision lines or building foundation positions for site development can be quickly marked with GNSS surveying, keeping errors between measured points within a few centimeters (a few in). Recently, solutions have emerged that overlay design lines on smartphone or tablet screens with AR display, reducing the need to read drawings and enabling intuitive and accurate stakeout.

Pile-center guidance

In piling work for bridges or building foundations, accurate guidance to the pile center is required. High-precision positioning equipment makes pile-center guidance efficient and reliable. For example, systems exist where the center coordinates of piles defined in the design are input into a GNSS receiver in advance, and a worker carrying the receiver on-site is guided to those coordinates. Following the guidance displayed on a tablet linked to the receiver, when the worker approaches the target, the display will show messages like “remaining: ○ cm,” enabling the worker to stand directly over the pile center. This allows even less experienced workers to locate pile positions without losing them and to always place piles at the design positions. For locations where physically driving piles is impossible (e.g., on hard concrete or right at a boundary), methods that virtually mark pile positions using AR technology, discussed later, are also used.

Structure installation

High-precision positioning is also powerful for installing large precast concrete elements and bridge girders. Traditionally, surveyors had to measure repeatedly and make fine adjustments to set structures at the designated position and elevation. By using RTK-GNSS, a receiver attached to the structure or a GNSS sensor mounted on the crane guiding the lift can provide real-time position coordinates to guide the placement. On site, workers can monitor the difference between the current coordinates (XYZ) of the structure and the design target value on a tablet and perform installation while instantly knowing adjustments such as “2 cm east, 1 cm up.” This enables one-shot placement at the designated position, reducing crane waiting time and manpower. High-precision positioning combined with digital monitoring improves both the quality and safety of structure installation.

Exterior works

High-precision positioning is used in exterior works with wide areas and many elements—road line markings, block walls, light poles, and installation of manholes and gutters for water and sewage. For example, when positioning curbs and gutters in road construction, GNSS allows direct confirmation of drawing coordinates on-site, minimizing misalignment even when aligning long runs. For buried water and sewage pipe work, recording as-built positions and depths accurately with GNSS produces data useful for future maintenance. In park development and site development exterior works, efforts have begun to confirm construction locations while AR-displaying the design model on-site. High-precision positioning enables low-error alignment across the entire site, improving finish accuracy of exterior elements and reducing rework.

Use of latest technologies such as AR navigation and point-cloud comparison

The fusion of high-precision positioning and digital technologies has led to notable recent use cases. Representative examples include AR (augmented reality)–based precise navigation, the comparison and use of point-cloud data, and data linkage to ICT construction.

Precise guidance via AR navigation

Combining high-precision positioning with AR display enables visual on-site guidance to “this is the target point.” For example, there are systems that display arrows or markers in AR on a smartphone or tablet screen to guide the user to a target point at centimeter-level (half-inch accuracy) precision. By selecting coordinate data shared in the cloud on the device’s map and instructing “go to this point,” an arrow on the screen will show direction and distance in real time. As you approach the destination, the display enlarges into a fine-adjustment mode, allowing pinpoint arrival at points such as pile positions or inspection locations. Additionally, by pointing a smartphone and showing an AR marker on-site, you can place a virtual mark on the ground. For instance, hidden boundary markers in grass or previously inspected crack locations can be reached reliably with AR navigation, making repeat inspections or photography at the exact same spot easy. Such AR navigation functions are only possible because of high-precision positioning and greatly contribute to labor-saving and improved accuracy of on-site tasks.

Comparative use of point-cloud data

With the spread of drone photogrammetry and LiDAR scanners, acquiring 3D point-cloud data at construction sites has become common. High-precision positioning further increases the value of this point-cloud data. Specifically, by assigning accurate position information obtained via GNSS to all point-cloud points, the acquired point cloud can be precisely aligned with design models or existing terrain data. As a result, progress of excavation or embankment can be immediately compared by analyzing differences between on-site scanned point clouds and the 3D design model, enabling calculation of remaining soil or backfill volumes. While point-cloud processing previously required specialized software and time, cloud platforms that visualize and measure point clouds have recently appeared. For example, a system where uploaded point clouds from the site can be checked on the web and arbitrary two-point distances, cross-sections, and volume differences can be measured on the spot. With point clouds accurately aligned by high-precision positioning, daily as-built management can be semi-automated, dramatically improving construction management efficiency. Even without specialized surveying knowledge, anyone can intuitively grasp terrain changes, smoothing information sharing between site and office.

Data linkage with ICT construction

Position data and 3D models obtained via high-precision positioning produce greater effects when linked with other ICT construction tools. For example, there is increasing use of integration with machine guidance and machine control systems for construction equipment. By equipping bulldozers, backhoes, and other machines with GNSS receivers and design data, operators can view target excavation lines and finished surfaces on a monitor in the cab while working. With GNSS-based real-time position awareness, consistent precision in operation is achievable regardless of operator experience, reducing the need for frequent surveyor checks. Also, as-built data obtained on site (e.g., high-precision GNSS-measured point clouds or photos) can be shared immediately with design teams or clients via the cloud and automatically reflected in daily progress reports. Software that automatically generates forms required for electronic delivery based on on-site measured data is also becoming common, realizing digital end-to-end data linkage from surveying to design, construction, and inspection. In this way, high-precision positioning serves as foundational technology for ICT construction and supports data-driven site operations.

Efficiency, safety, repeatability, and labor savings brought by improved positioning accuracy

The benefits expected from adopting high-precision positioning technologies are wide-ranging, but especially four pillars stand out: “efficiency,” “improved safety,” “ensured repeatability of work,” and “labor savings.”

Improved work efficiency and productivity

Centimeter-level (half-inch accuracy) positioning greatly reduces unnecessary rework and adjustments in surveying and construction. Since the target precision can be achieved with a single measurement or stakeout, the number of retries decreases, accelerating overall work speed. Also, if site personnel themselves can operate high-precision positioning equipment, tasks that previously required specialized surveying departments or outsourcing can be performed in-house immediately. For example, if tasks that formerly required 2–3 people for batter board setup or as-built measurement can be completed by one person, manpower allocation becomes more efficient and productivity increases. In practice, on one site, a team using a tablet and GNSS receiver for as-built management reported elimination of waiting time for surveying and a shortened construction cycle. High-precision positioning thus contributes to overall day-to-day on-site efficiency.

Improved safety

Higher surveying accuracy also contributes to safety. Traditionally, surveying or verification in hazardous areas required workers to take risks by going to the site. Using high-precision GNSS and related technologies, more measurements and observations can be made without personnel entering dangerous areas. For example, conditions of high slopes can be documented from a safe distance using a GNSS-equipped camera, and accurate position information can be linked to the photos for later analysis. Also, point measurements on busy roads take less time with GNSS, reducing workers’ exposure. AR-based measures that set virtual “do not approach” zones for hazardous areas have begun to appear, and precise position awareness helps visualize near-miss incidents and dangerous areas. Furthermore, as machine-controlled construction with GNSS advances, the need for personnel guiding heavy machinery at close range decreases, lowering the risk of contact accidents. Thus, high-precision positioning greatly contributes to site safety.

Improved repeatability of measurement results

“Repeatability” means obtaining the same result each time the same measurement is performed. With high-precision positioning, it becomes easy to revisit and verify coordinates or measurement points accurately at a later date. For example, in post-disaster recovery sites where repeated fixed-point observations are required, if the coordinates measured by GNSS at the initial survey are saved, subsequent visits can use AR navigation to return to the exact same coordinates and capture photos from the same position and orientation. This enables much more accurate and simple comparisons of changes over time or differences before and after construction. In the past, relying on paper drawings or human memory sometimes resulted in slight misalignments going unnoticed during comparisons, but digital coordinate management prevents such errors. For point-cloud acquisition too, if a common reference coordinate system is maintained, point clouds taken at different times can be overlaid for accurate difference analysis. These are all benefits of repeatability provided by high-precision positioning and are key to data-driven quality and progress management.

Contribution to labor savings

Labor savings and automation are urgent challenges for the construction industry facing severe workforce shortages. Introducing high-precision positioning helps standardize tasks that depended on specialists like surveyors, resulting in reduced required personnel. For instance, as mentioned earlier, if one person can handle as-built measurement and layout marking, teams that previously needed 2–3 people can be reorganized. Also, with GNSS and AR support enabling less experienced staff to perform at the same accuracy as veterans, dependency on individuals is reduced. In the future, automated construction by GNSS-guided machines and autonomous surveying by drones and robots will further spread. In those scenarios, high-precision positioning that provides accurate location information will be the core of automation. Labor savings are not just about reducing headcount but about enabling a limited workforce to service more sites and redirecting human resources to creative tasks. The spread of high-precision positioning strongly supports on-site labor-saving and effective use of personnel.

Easy high-precision positioning and operational benefits with smartphones × GNSS × AR

A new operational style combining smartphones or tablets with GNSS receivers and AR technology has dramatically lowered the barrier to high-precision positioning. Traditional RTK-GNSS receivers were expensive, survey-dedicated devices requiring specialized knowledge, but recently compact GNSS devices that attach to smartphones have appeared, creating an environment where anyone on site can easily use centimeter-level (half-inch accuracy) positioning.

:contentReference[oaicite:0]{index=0} *An example of a small GNSS receiver that can be attached to a smartphone (LRTK Phone). Devices like this enable easy centimeter-level (half-inch accuracy) positioning. While high-precision GNSS equipment was once mainly stationary, integrating it with smartphones greatly improves on-site mobility.*

The biggest benefits of these smartphone GNSS devices are their ease of use and versatility. Smartphones are tools that field technicians always carry, so there’s no need to carry additional dedicated equipment. Attaching a pocket-sized receiver to a smartphone and launching an app instantly turns the smartphone into a surveying instrument. Because you operate through a familiar smartphone interface, you can start using it intuitively without extensive training. For example, with just a button press in an app you can record high-precision coordinates of the current location or display a 3D model in AR on the screen.

Also, smartphone-cloud integration enables real-time information sharing. Data measured with a smartphone GNSS device can be uploaded directly to cloud storage and shared internally and externally. Office personnel can immediately view coordinate-tagged photos or point-cloud data acquired on-site and issue instructions. This reduces communication loss between site and office and speeds decision-making. It also eliminates the hassle of bringing paper records back for整理, shortening administrative work time.

Furthermore, the smartphone × GNSS combination is cost-effective. A full set of dedicated high-precision positioning equipment can cost several million yen, but smartphone GNSS devices leverage existing smartphones, lowering initial investment. The devices themselves are becoming relatively inexpensive through miniaturization and mass production, with product price ranges that make it feasible to equip each employee. For example, a domestic startup’s smartphone-mounted GNSS receiver offers high performance at a very reasonable price, and adoption among field practitioners is increasing.

Thus, the smartphone × GNSS × AR model is set to revolutionize the integration of high-precision positioning into daily operations. The convenience of being able to pull a device out and measure anytime has opened the door to people who previously avoided surveying. As a result, accurate data is collected across sites, enabling a more precise PDCA cycle for construction and maintenance. The ability to “just measure the site for now” or “check immediately on the spot” enables agile operations, and the potential value of smartphone GNSS devices is very large.

Implementation steps for the smartphone GNSS device “LRTK”

So, what steps should you take to introduce a smartphone GNSS device on-site? As an example, below are implementation steps for LRTK, a smartphone-mounted RTK-GNSS receiver. LRTK offers ease of use and high functionality, but the basic flow is similar for other similar devices.

• Prepare equipment and apps: First, prepare the smartphone or tablet and the LRTK receiver. Check compatible OS and models, and prepare any dedicated smartphone cases or mounting attachments if necessary. Install the manufacturer-provided app on the smartphone.

• Initial setup and connection to correction service: Attach the LRTK receiver to the smartphone and launch the app. On first launch, configure the positioning augmentation service to use. For sites with Internet access, connect to an Ntrip base-station network; if out of communication range, switch to LRTK’s QZSS CLAS mode if available. Also select the coordinate system to output positioning results (e.g., WGS84 or plane rectangular coordinate systems) in the app.

• Operation check and trial surveying: At the start of deployment, perform positioning at known control points to verify that centimeter-level (half-inch accuracy) precision is achieved. For example, place LRTK on a control point and compare the measured coordinates with the known coordinate values. Also check whether stable values are obtained using functions such as averaged positioning. If there are no issues, try simple as-built measurements or layout marking on company grounds and compare results with traditional methods.

• Full application on-site: Once users are comfortable with the device, start using LRTK on actual construction sites. Begin with relatively low-risk tasks such as as-built management, and gradually expand to layout marking and pile positioning. Because radio conditions (satellite visibility and multipath) differ by site, monitor positioning status each time and learn appropriate usage.

• Establish operation rules and provide training: When multiple sites begin using LRTK, establish internal operating rules. For example, decide file naming conventions for positioning data, methods for saving to the cloud, and procedures for handling low-accuracy situations (re-measurement or verification by alternate methods). Training site staff is also important. Even though operation is simple, make sure to share safe handling procedures and basic knowledge (e.g., recognizing places with poor satellite reception).

• Evaluate effects and provide feedback: After some period of operation, quantitatively and qualitatively evaluate productivity improvements and contributions to accuracy and quality. For example, collect outcomes such as “average time for batter board setup shortened by 30%” or “as-built inspections had zero rework due to missed measurements.” Use site feedback to decide on wider deployment (extend to other departments, add devices).

The above outlines the general flow for LRTK introduction. The key point is to start small, verify effects, and scale up. Because these are easy-to-use tools, field-oriented trials and iterative improvements are essential to integrate them into site routines. Once trusted on site, devices like LRTK become indispensable daily tools that fundamentally change how positioning tasks are done.

Conclusion: Start high-precision positioning with LRTK

High-precision positioning technologies have evolved from tools for a few specialists into familiar tools usable by all site workers. The smartphone GNSS device LRTK, a symbol of this change, lowers the barrier to centimeter-level (half-inch accuracy) positioning and creates an environment where anyone can handle accurate position information at any time. The role of high-precision positioning in improving productivity and ensuring safety on construction sites will only grow.

If you have not yet used high-precision positioning on-site, consider starting with a small-scale introduction. Lightweight devices like LRTK require less initial investment and operational burden, making trials easy. Once you try them, you may find their accuracy and convenience make you feel “we can’t go back to the old ways.” Introducing high-precision positioning is a step not only toward operational efficiency but also toward a new stage of data-driven construction management.

Actively adopt high-precision positioning to raise the quality and efficiency of your construction work one level. Smartphone GNSS solutions like LRTK will be a powerful partner. The future of construction sites is steadily approaching smart construction supported by accurate data. Ride this wave and realize construction innovation through high-precision positioning at your sites.