One-Person Surveying: What You Can Achieve! 10 Field Case Studies Using LRTK

Traditionally, survey work in the field has been carried out by two to three people. However, with the advent of the latest technologies, "one-person surveying" has become a reality, and conventional practices on site are undergoing major change. In this article, we explain the reasons and background behind the growing attention to one-person surveying, and the technical characteristics of LRTK (a smartphone-mounted RTK-GNSS device) that hold the key. Furthermore, we introduce a carefully selected set of 10 real-world cases in which LRTK was used to achieve high-precision surveying by a single operator, drawn from a wide range of fields including construction, surveying, agriculture, disaster prevention, and urban management. Be sure to check the concrete results and benefits to see how far on-site operations can be streamlined through one-person surveying.

Reasons and Background Behind the Growing Interest in Single-Person Surveying

In the construction and civil engineering industry in recent years, severe labor shortages and an aging workforce have become serious issues. Veteran surveying technicians are retiring one after another, and continuing the traditional practice of "relying on people for surveying" is becoming increasingly difficult. At the same time, job sites require precise survey data, and how to carry out surveying efficiently with limited personnel is a major concern. At the forefront of attention is a new approach that leverages satellite positioning technologies such as RTK-GNSS (Real-Time Kinematic GPS), enabling small teams, and in extreme cases a single person to complete the surveying work, to finish surveying tasks.

Traditional surveying used tools such as measuring tapes, staffs, and transits (surveying instruments mounted on tripods), requiring at least two people, with one person operating the instrument and another holding the staff (leveling rod) at a distance. When measuring large sites, it was not uncommon for the work to take a full day, and both setup and pack-up required significant time and effort. Manual surveying also carries the risk of human error. Misreads or recording mistakes can lead to rework in later stages, potentially causing schedule delays and increased costs.

Against this background, initiatives promoted by the Ministry of Land, Infrastructure, Transport and Tourism, such as i-Construction, have emphasized “efficient surveying with fewer people in less time” and “productivity improvement,” accelerating surveying DX (digital transformation). Among these, one-person surveying is expected to be a trump card that can simultaneously address labor shortages and improve accuracy. By leveraging the latest GNSS technology, even inexperienced operators can survey wide areas in a short time, with accuracy equal to or better than conventional methods—such possibilities are now opening up.

Technical Features of LRTK (Easy, High-Precision, Cloud Integration)

A representative technology that supports solo surveying is LRTK. LRTK (El-Arr-Tee-Kay) is an ultra-compact surveying device for smartphones developed by Refixia Co., Ltd., a startup originating from the Tokyo Institute of Technology. Simply attach it to an iPhone or iPad, and the device itself transforms the terminal into a surveying instrument with centimeter-level accuracy.

The main technical features of LRTK are as follows.

• Convenience (compact, lightweight and integrated with your smartphone): The LRTK device itself is pocket-sized, weighing approximately 165 g and about 1 cm thick. Attach it to the back of your smartphone using a dedicated cover or mount and simply connect via Bluetooth or Lightning — you’re ready. Carry just this one device in your pocket and take it out to start surveying the moment you need it. Previously, you had to carry several kilograms of equipment and set up a tripod, but with LRTK you can complete everything from on-site surveying to staking alone with just your smartphone.

• Centimeter-level high-precision positioning: LRTK is compatible with the RTK method and can determine positions with surveying-grade accuracy of approximately ±2–3 cm horizontally and ±3–4 cm vertically. While the GPS built into smartphones typically has errors of 5–10 m, LRTK reduces those errors to just a few centimeters using a dedicated antenna and RTK corrections. Because it supports the electronic reference point network that serves as base stations (Ntrip) and Japan’s quasi-zenith satellite Michibiki (CLAS augmentation signals), real-time high-precision positioning is possible anywhere in the country. This makes it fully capable of meeting the demands of surveys requiring high accuracy, such as topographic surveys, boundary checks, and as-built verification.

• Cloud integration and data sharing: Using a smartphone app dedicated to LRTK, measured data is automatically uploaded to the LRTK Cloud on the spot. Coordinates of survey points, photos, and memo information are plotted on a map in the cloud, and colleagues in the office can immediately check the situation on a web screen. Measurement results can be downloaded in CSV, PDF, or SIMA formats and can be used immediately for CAD drawings and report preparation. Also, if you send stakeholders a shared URL issued on the cloud, anyone can view the latest data without logging in, making information sharing with clients and partner companies smooth. By enabling real-time on-site visualization, the time required for post-survey data organization and communication can be drastically reduced.

• Versatile features (point cloud measurement, photo positioning, AR display, etc.): The LRTK system is equipped with various functions that promote on-site DX, not just measuring point coordinates. For example, the detailed point cloud scan feature, which integrates with an iPhone’s LiDAR scanner, allows you to capture surrounding terrain and structures as 3D point cloud data while walking. The measured point clouds are automatically assigned absolute coordinates (latitude, longitude, height), so you can model the site in three dimensions and use it directly for earthwork volume calculations and drafting. It also includes a function that records the photo’s capture location and orientation simply by taking pictures with a smartphone camera. The photos are linked to maps in the cloud, making it immediately clear which location and direction each photo shows. Furthermore, you can use an AR (augmented reality) feature that overlays the obtained survey data and design models onto the smartphone camera view. This enables visualization of “points on the design” in real space, providing intuitive surveying and construction support such as stakeout position guidance and overlay displays of the completed form.

• Offline capability and safety: LRTK delivers powerful performance even outside internet coverage. Because it can receive the CLAS signal from Michibiki directly, it enables high-precision positioning using satellite augmentation information even in mountainous areas or disaster sites where cellular signals do not reach. Even in large-scale disasters where base stations and communications are cut off, a single person can obtain and record on-site location information. Also, LRTK has a built-in battery that allows about six hours of continuous operation. It can be extended by powering it from a mobile power bank, so it is reliable for long surveying sessions and work in remote locations. Its compact, lightweight design makes it easy to handle even in areas with poor footing, and being able to take measurements while minimizing entry into hazardous locations is also a major safety advantage.

• Cost-effectiveness: Conventional high-precision RTK surveying equipment often cost several million yen and large-scale units were not uncommon, but thanks to LRTK's simple design used in combination with a smartphone, upfront costs are significantly reduced. Because the price is very reasonable, deploying one unit per person is realistic. This allows multiple on-site staff to each carry an LRTK and perform surveying and recording at their convenience, leading to improved overall site productivity.

As described above, LRTK is an innovative tool that enables centimeter-accurate surveying "by anyone, anywhere, right away." Now, let's take a concrete look at real-world case studies where LRTK was used for one-person surveying. We'll introduce the kinds of benefits being realized across various fields—not only construction and surveying, but also agriculture, disaster prevention, and infrastructure management.

10 On-site Examples of LRTK Use

Case 1: Rapid Damage Survey at a Disaster Site (Noto Peninsula Earthquake)

Overview: In the 2023 earthquake off the Noto Peninsula, the strengths of single-person surveying were demonstrated. Immediately after the disaster, when roads were severed and base stations had lost power causing communications to fail, a member of the disaster response team conducted damage surveys using a single smartphone equipped with LRTK. Even on rubble-strewn sites where large surveying instruments could not be brought in, LRTK enables high-precision position data to be collected simply by walking with the smartphone mounted on a helmet. By receiving augmentation signals from the Michibiki satellites, centimeter-level positioning even outside internet coverage is possible, allowing accurate coordinates of damaged locations to be recorded despite communication outages.

Effect: Because surveying could be performed nimbly by a single person, investigations were completed with the minimum number of personnel even in hazardous areas where aftershocks continued. The collected data was immediately mapped at the on-site recovery headquarters, and the extent of the damage was quickly shared. As a result, the lead time to formulate recovery plans was greatly shortened, leading to earlier commencement of restoration work. In addition, because municipal staff were able to carry out measurements of the disaster situation themselves—work that had previously been outsourced to surveying companies—this also contributed to reduced outsourcing costs and the internalization of technical capabilities. The rapid situational awareness and information sharing enabled by single-person surveying greatly contributed to speeding up life-saving efforts and infrastructure restoration.

Case 2: One-person Volume Measurement at a Landslide Site

Overview: Solo surveying is proving effective even at landslide sites caused by intense torrential rainfall. In one such heavy-rain disaster, the person in charge inspected a mountainside buried by collapsed debris alone. Remaining in a safe position, they walked around the perimeter of the debris accumulation area using LRTK's continuous positioning function, continuously recording coordinates at a rate of up to 10 points per second. In a short time they accurately measured the extent of the collapsed material and immediately calculated the collapsed soil volume (volume) from that data.

Effect: Where previously teams had to risk danger conducting surveys with multiple people and then calculate earthwork volumes after returning with the data, with LRTK you can measure on site and complete the calculations immediately. Because volume information for the soil and debris is obtained instantly, teams can accurately determine the necessary heavy machinery and number of dump trucks, making the planning of restoration work smoother. Since measurements can be carried out by a single person, there is no need for time-consuming personnel arrangements, and unnecessary entry is avoided, improving safety. As a result, this is a good example of speeding up the initial disaster response while also contributing to worker safety.

Case 3: Quantity management at earthwork sites using point cloud scanning

Overview: In civil engineering works (site formation, embankment, and excavation), surveying to accurately determine as-built shapes and earthwork volumes often takes considerable time. On one medium-sized earthworks site, substantial labor savings were achieved through mobile scanning using LRTK. A single operator walked the site holding an LRTK mounted to an iPhone, collecting LiDAR point cloud data of the ground surface. For example, for a development area of about 50 m by 50 m, a scan of only about five minutes produced point cloud data on the order of hundreds of thousands of points representing the terrain's shape.

Effect: This method dramatically shortened a workflow that previously required manually surveying control points one by one. Measurements around batter boards and earthwork volume checks that once took days are now completed on site. Because the acquired point clouds are assigned absolute coordinates from the outset, there is no need for alignment back at the office. By comparing point cloud datasets, you can instantly calculate the volumes of fill and excavation, enabling real-time earthwork quantity management and as-built inspection. The amount of information and the speed achievable by a single operator increased so much that site personnel were astonished, saying it felt like having double the manpower. As a result, this case achieved improved construction management efficiency and shortened project schedules.

Case 4: One-person marking on steep slopes and bedrock (AR staking)

Overview: Laying out reference lines for structures and marking stake positions (sumi-dashi) is usually a cumbersome task requiring two or more people. In particular, on bedrock or steep slopes it has been difficult to drive wooden stakes and set out positions. At one tunnel road construction site, they attempted to indicate stake positions single-handedly by leveraging LRTK and AR technology. They uploaded the coordinate data from the design drawings to the LRTK cloud, and when viewed on site through a smartphone camera, a virtual stake marker is displayed on the screen via AR. Using that marker as a guide, workers were able to accurately pinpoint locations even on hard ground where physical stakes could not be driven.

Effect: With this AR stake placement, the positioning work that had previously required survey teams to travel back and forth could be performed continuously by a single person. By simply moving to the next installation position displayed on the smartphone screen, they can mark stake points in sequence. As a result, stake positioning across a wide area can be completed in a short time and staffing requirements reduced. In particular, because no assistant is required even in locations with poor footing, safety has also improved. It is also possible to measure coordinates on the spot and immediately display them in AR in response to on-site instructions like “I want a stake here,” providing flexibility that allows the site supervisor’s intent to be shared instantly. Solo surveying combined with AR is a good example of achieving both significant labor savings in surveying processes and improved accuracy.

Case 5: Consensus building for construction through AR visualization of BIM/CIM models

Overview: On construction sites using 3D BIM/CIM models, it can be difficult to convey the finished image to all stakeholders with paper drawings alone. At one road construction site, an LRTK was attached to a tablet (iPad) and used in meetings to display the design 3D model as AR over the site scenery. By overlaying the planned embankment shapes and structure models onto the actual terrain, everyone—from the client and construction staff to heavy equipment operators and nearby residents—was able to intuitively understand the finished appearance.

Effect: Seeing the completed model emerge on the tablet screen at the site deepened stakeholders' understanding and smoothed communication. What had previously been explained by pointing to drawings could now be shared on-site simply by "viewing" the model, reducing rework caused by misunderstandings. On one site, this method made communication among construction personnel markedly smoother, and there were reports that errors in sharing design intent decreased. Additionally, during as-built inspections, overlaying design data and the constructed elements on a tablet made it possible to detect and correct defects on the spot. "Site visualization" through AR supported consensus-building and quality control, leading to improvements in productivity and construction quality.

Case 6: High-precision location recording and cloud sharing for road and bridge inspections

Overview: In infrastructure inspections of roads, bridges, and other assets managed by local governments, accurately recording the locations of anomalies is the key to maintenance. Traditionally, inspection results were managed with paper ledgers and photographs, and there were cases where teams relied on vague descriptions such as “streetlight failure approximately 50 m east of the XX intersection.” To address this, one city introduced a system in which maintenance inspectors photograph and geolocate faults using LRTK-equipped smartphones, and share the data. When an inspector finds a burned-out streetlight bulb, they only need to take a photo with their smartphone for the latitude, longitude, and date/time to be tagged, and the information is automatically uploaded to the cloud.

Effect: In the office, staff can look at the photos and the plotted points on the map that were sent and immediately grasp the exact location and situation. For example, in the past they might hear “a streetlight near XX is out” and have to hunt around the site, but if they navigate using the coordinates obtained with LRTK they can arrive on site in one go. As a result, repair crews can head straight to the site without wasted time, and response speed has improved dramatically. In addition, the accumulated high-precision positional data is useful for long-term monitoring of infrastructure assets. Measuring the same bridge pier with LRTK every year and comparing the coordinates can capture long-term settlement and displacement down to the centimeter level. Anomaly detection that used to depend on individual judgment has been transformed into objective, data-based evaluation, and the accuracy and efficiency of maintenance management have improved. By incorporating a smartphone surveying tool for each inspector into inspection operations, site information is shared in real time and with accuracy, leading to smarter infrastructure preservation.

Case 7: Bulk surveying and asset register preparation for urban infrastructure assets (signage, etc.)

Overview: Cities are dotted with various facilities—streetlights, traffic signals, fire hydrants, benches, playground equipment, and more—and some municipalities face the challenge of creating a digital registry of those facilities' accurate location data. For older installed equipment, coordinate information is often incomplete or only paper maps exist. To address this, one city launched a project in which staff used LRTK to survey road signs across the entire city and update the location registry. Staff approached each signpost one by one and, by pressing a button on a smartphone, measured the coordinates of the installation location. They also entered attribute information such as management numbers and types, and aggregated the data in the cloud.

Effect: As a result of this initiative, a latitude/longitude list for all signs was completed with centimeter-level accuracy, enabling a digital understanding of the up-to-date layout of urban assets. Managing installation and removal histories in the cloud also streamlines planning for future equipment replacements. For example, during road construction, knowing the exact positions of buried utilities and signs in advance reduces the risk of damage during excavation and improves safety. In addition, when facilities are damaged by major disasters or traffic accidents, affected locations can be identified on a map instantly, supporting rapid response. Using AR features, you can overlay the positions of underground pipes and cables onto the scene seen through a camera on site, which can be applied to pre-excavation checks. By steadily building asset information through easy on-site surveying with LRTK, constructing a digital twin of urban infrastructure (a detailed digital model of the real city) is within reach. This case demonstrates how methodical asset registry maintenance carried out through one-person surveying contributed to laying the groundwork for a smart city.

Case 8: Routine Inspection and Smart Management of Agricultural Waterways

Summary: The benefits of solo surveying are becoming apparent even in rural areas. In the agricultural administration division of a certain local government, LRTK was introduced for inspections of agricultural waterways and reservoirs spread across a wide area. Many agricultural civil engineering structures have been in use for decades, and accurate location or shape data is often lacking. So staff patrolled along the waterways and embankments with an LRTK-equipped smartphone in hand. Each time they discovered cracks or leaks, they took photos, geolocated the locations, and recorded them in the cloud.

Effect: As a result, facility management, which until now relied on staff experience and intuition, has shifted to being data-driven. By reviewing geotagged photos stored in the cloud from the office, they can rationally set repair priorities and plan work schedules. For example, if the data clearly shows that “there was a leak in the same spot last year,” they can take focused reinforcement measures. Also, when waterways are damaged by heavy rain or earthquakes, the exact coordinates of the damage can be recorded and shared immediately, speeding up the preparation of documents for subsidy applications and requests for assistance. This is a case where, even with a limited number of personnel, using LRTK to efficiently patrol and record has improved the standard of maintenance and management for agricultural infrastructure distributed across a wide area. Patrol inspections that had been conducted with paper maps and notebooks have been digitized, making it easier for staff to share information, which enables stable facility management even amid generational turnover.

Case 9: Streamlining Boundary Surveys and Stake Position Verification

Overview: One-person surveying tools are proving useful even in the work of private surveyors and land and house surveyors. For example, when verifying property boundaries, it has often been time-consuming to relocate boundary stakes or survey points that were placed in the past. If they are hidden by vegetation, or if the previous surveyor was different and you don’t know the approximate position, you end up searching around the site. Therefore, one surveying office registered the known boundary coordinates in the LRTK Cloud in advance and introduced a method of locating stakes on site using the coordinate navigation feature. When they go to the site with a smartphone and select the target boundary point, an arrow and the distance are displayed on the screen in real time. By simply following it, you are guided to the stake’s location with pinpoint accuracy within a few centimeters.

Effect: With this method, it became possible to revisit boundary stakes and survey markers in a short time without losing them. In particular, even for repeated fixed-point observations or field surveys conducted at long intervals, the exact points measured previously can be easily reproduced. As a result, the time spent on boundary verification was greatly reduced and survey efficiency improved. In addition, because photos and notes of boundary markers taken in the past can be reviewed in chronological order on the LRTK app, it also helps confirm changes over time and prevent oversights. By enabling boundary surveys to be completed by a single person, small surveying offices can handle many projects in parallel and respond to clients faster. A one-person surveying tool that improves efficiency without compromising accuracy is a powerful ally not only in public but also in private surveying sites.

Case 10: Safe Surveying with Non-Contact Positioning Indoors and at Heights

Overview: LRTK can be adapted, with creative measures, not only for outdoor use but also for measurements under structures and at elevated locations where GPS reception is poor. For example, in places where GNSS signals are usually not receivable—such as under bridge girders or inside tunnels—LRTK’s indoor positioning mode is effective. By first obtaining a reference position at a location where GPS is available, and then calculating relative positions inertially after entering an area outside GPS coverage, it enables continued centimeter-level positioning. In fact, in a case where LRTK was used for an inspection of a bridge’s underside, point acquisition beneath a bridge pier was safely completed by a single person.

Also, for measuring points at heights that are out of reach, LRTK’s subject positioning function (non-contact positioning) is useful. For example, if you want to measure the coordinates of a bolt located at the top of a slope or in a high position on a bridge, instead of forcibly extending a pole or having someone climb up, you can simply capture the target with a smartphone camera from a distance and press the positioning button to obtain the latitude, longitude, and elevation of that point. During an inspection of a plant facility, valve mounting positions were photo-positioned from the ground, allowing the coordinates needed to update the drawings to be obtained without having to deploy an aerial work platform.

Effect: These functions made it possible to acquire data from locations that were previously unmeasurable and to reduce labor for hazardous high-elevation work. In surveying beneath bridges, it eliminated the need to erect temporary scaffolding or have multiple people peering in, providing significant safety and cost benefits. The non-contact positioning feature enables accurate positional information for inspections of equipment at height without using tape measures or stepladders, resulting not only in reduced work time and effort but also in lowered risks for workers. The one-person surveying tool has made hard-to-measure locations reachable and is a prime example of expanding the scope of on-site work.

Summary: The ease of surveying with LRTK and the benefits of adoption

That concludes our presentation of 10 on-site case studies using LRTK. You may have thought, "Can one person really accomplish this much in surveying?!" With the advent of LRTK, surveying work is no longer the exclusive preserve of experienced veterans; it is being transformed into an everyday tool that anyone can use. All you need at the site is a smartphone and an LRTK, and high-precision surveying, inspection records, photography, and data sharing can be completed in no time.

Put simply, the advantages of single-person surveying are a dramatic increase in productivity and safety. Because the necessary surveying data can be obtained with a small team in a short amount of time, the burden of arranging personnel and the time spent on site are reduced, allowing those resources to be allocated to other tasks. Direct effects such as reduced labor costs and shorter construction schedules also contribute to cost management for companies and municipalities. Additionally, because the work can be completed by a single person, it avoids close contact and is well suited to the contactless and remote approaches that gained attention during the COVID-19 pandemic.

Precision and quality assurance are also strengths of one-person surveying. Tools like LRTK have apps that automatically guide and record, which reduces the risk of human error. Because less-experienced staff can take accurate measurements without relying on a veteran's intuition, concerns about skills transfer are also alleviated. Since data measured in the field can be checked and shared on the spot in real time, this also enables early detection of mistakes and prevents rework. In short, one-person surveying is bringing the field's ideal of "fast, cheap, safe, and accurate" much closer.

Furthermore, in recent years national and local governments have also stepped up their digitalization support measures. There are cases where subsidies can be used to introduce high-precision GNSS equipment, and there are programs that encourage equipment procurement as part of strengthening disaster response capabilities. Even small and medium-sized enterprises and municipalities that had been hesitant to adopt such technology because of the high cost can realistically adopt cost-effective solutions like LRTK.

The new approach of one-person surveying is poised to bring significant changes not only to the surveying and construction industries but also to infrastructure maintenance and management across society. With LRTK, a smartphone becomes "the site's eyes and feet", allowing on-site conditions to be digitally recorded and shared exactly as they are. This is truly a driving force behind on-site DX and can be regarded as part of work-style reform.

Finally, if in your workplace or project you feel that “surveying takes too much manpower or time” or “you want to gather site information more efficiently,” please consider solo surveying with LRTK. By adopting this technology, which combines ease of use with high accuracy, the barriers to surveying are dramatically lowered and the possibilities at the site expand. Its intuitive operation can be handled even by those who are not experts, so it can become an immediate asset right after implementation. The extra time and capacity gained from one-person surveying can surely be redirected toward other value-creating activities. Why not step up your site to the next stage with the new surveying style that LRTK enables?