What Solo Surveying Can Achieve! 10 Field Case Studies of LRTK Applications

Traditionally, surveying sites typically required two to three people to carry out the work. But now, with the advent of the latest technologies, "one-person surveying" has become a reality, and the conventional practices at worksites are being significantly transformed. In this article, we explain the reasons and background why one-person surveying is gaining attention, and the technical features of LRTK (a smartphone-mounted RTK-GNSS device) that hold the key. Furthermore, we introduce 10 field case studies where a single person achieved high-precision surveying, carefully selected from a wide range of fields including construction, surveying, agriculture, disaster prevention, and urban management. Please review the concrete results and effects to see how far field operations can be streamlined by one-person surveying.

Reasons and Background for the Growing Attention to One-Person Surveying

In recent years, the construction and civil engineering industries have been facing serious labor shortages and an aging workforce. Veteran surveying technicians are retiring one after another, making it increasingly difficult to continue the traditional practice of "surveying that relies on people". At the same time, job sites demand precise surveying data, and how to carry out surveying efficiently with limited personnel has become a major theme. One approach gaining attention is the use of satellite positioning technologies such as RTK-GNSS (real-time kinematic GPS) to enable work with a small crew, and in the extreme case, to complete surveying work by a single person.

In conventional surveying, tools such as measuring tapes, staffs, and transits (surveying instruments mounted on tripods) were used, requiring at least two people—one to operate the instrument and another to hold the staff (survey rod) at a distant point. Measuring a large site often took an entire day, and the process from setup to takedown was both time-consuming and labor-intensive. Manual surveying also carried the risk of human error. Misreadings or recording mistakes could cause rework in later stages, leading to schedule delays and increased costs.

Against this backdrop, initiatives promoted by the Ministry of Land, Infrastructure, Transport and Tourism (MLIT), such as i-Construction, have emphasized "efficient surveying with fewer personnel and shorter time" and "increased productivity," accelerating surveying DX (digital transformation). Among these, one-person surveying is expected as a trump card that can simultaneously resolve labor shortages and improve accuracy. By leveraging the latest GNSS technology, even relatively inexperienced operators can survey wide areas in a short time, and the accuracy is 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 one-person surveying is LRTK. LRTK (Eru Āru Tī Kē) is a ultra-compact surveying device for smartphones developed by Reflexia Inc., a startup originating from the Tokyo Institute of Technology. By simply attaching it to an iPhone or iPad, the terminal itself transforms into a surveying instrument with centimeter-level accuracy (cm level accuracy (half-inch accuracy)).

The main technical features of LRTK are as follows.

• Ease of use (compact, lightweight, integrated with a smartphone): The LRTK device itself weighs approximately 165 g and is a pocket-sized unit about 1 cm (0.4 in) thick. Attach it to the back of your smartphone with a dedicated cover or mount, and simply connect via Bluetooth or Lightning to be ready. You can carry this single device in your pocket and, when needed, take it out and start surveying immediately. Traditionally you had to carry several kilograms of equipment and set up a tripod, but with LRTK you get the convenience that with just a smartphone, a single person can complete everything from on-site surveying to driving stakes.

• Centimeter-level high-precision positioning (cm level accuracy, half-inch accuracy): LRTK supports the RTK method and can determine positions with survey-instrument-level accuracy of approximately ±2-3 cm (±0.8-1.2 in) horizontally and ±3-4 cm (±1.2-1.6 in) vertically. While built-in smartphone GPS typically has errors of 5-10 m (16.4-32.8 ft), LRTK reduces errors at once to just a few cm (a few in) through a dedicated antenna and RTK corrections. Because it supports the electronic reference point network (Ntrip) that serves as base stations and Japan's quasi-zenith satellite Michibiki (CLAS augmentation signal), high-precision positioning is possible in real time anywhere in the country. This enables it to adequately meet the needs of surveys that require high accuracy, such as topographic surveying, boundary verification, and construction as-built management.

• Cloud integration and data sharing: Using the dedicated LRTK smartphone app, measured data is automatically uploaded on-site to the LRTK Cloud. Coordinate values, photos, and note information for survey points are plotted on a cloud-based map, allowing colleagues in the office to instantly check the situation via a web interface. Measurement results can be downloaded in CSV, PDF, or SIMA formats, making them immediately usable for CAD drawings and report generation. In addition, if you send stakeholders the shareable URL issued on the cloud, anyone can view the latest data without logging in, so information sharing with clients and partner companies is smooth. The real-time visualization of the field greatly reduces the time required for post-survey data organization and communication.

• Diverse functions (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 scanning function, which works with the iPhone’s LiDAR scanner, allows you to capture the surrounding terrain and structures as 3D point cloud data while walking. Since measured point clouds are automatically assigned absolute coordinates (latitude, longitude, altitude), you can model the site in three dimensions and use it directly for earthwork calculations and drafting. There is also a function that records the photo’s capture location and orientation simply by taking a picture with a smartphone camera. Photos are linked to maps in the cloud, making it immediately clear which location and direction each photo shows. In addition, you can use AR (augmented reality) features to overlay obtained survey data and design models on 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 finished appearance.

• Offline capability and safety: LRTK remains effective even outside internet coverage. Because it can directly receive the CLAS signal from Michibiki, high-precision positioning is possible using satellite augmentation information even in mountainous areas without mobile signal or at disaster sites. Even in large-scale disasters where base stations and communications are cut off, a single person can obtain and record on-site position information. LRTK has a built-in battery that allows continuous operation for about 6 hours, and operating time can be extended by powering it from a mobile battery, so it is reliable for long surveys or work in remote locations. Its compact, lightweight design also makes it easy to handle even in areas with poor footing, and the ability to take measurements while minimizing entry into hazardous areas is a major safety advantage.

• Cost performance: Conventional high-precision RTK surveying equipment often consisted of large machines costing several million yen, but thanks to LRTK’s simple design used in combination with a smartphone, initial costs have been greatly reduced. Because the price is very reasonable, deploying one unit per person is realistic. This allows multiple staff on site to each carry an LRTK and perform surveying and recording whenever they want, leading to an overall improvement in site productivity.

As described above, LRTK is an innovative tool that enables "anyone, anywhere, immediately" to perform centimeter-accuracy surveying (cm level accuracy (half-inch accuracy)). Now, let’s take a concrete look at a field case where this LRTK was actually used to carry out a one-person survey. We will introduce what kinds of effects are being produced in various fields — not only construction and surveying, but also agriculture, disaster prevention, and infrastructure management.

10 Real-World Examples of LRTK Applications

Case 1: Rapid Damage Surveying 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, with roads cut off and base stations without power leaving communications severed, a disaster response team member conducted a damage survey with a single smartphone equipped with LRTK. Even in rubble-strewn sites where bringing large surveying equipment was impossible, LRTK allows a smartphone mounted on a helmet to collect high-precision position data simply by walking. By receiving correction signals from the Michibiki satellites, centimeter-level positioning (cm level accuracy, half-inch accuracy) is possible even outside internet coverage, enabling damaged locations to be recorded with accurate coordinates despite communication outages.

Effect: Because it allows a single person to move nimbly while surveying, investigations could be completed with the minimum number of personnel even in hazardous areas where aftershocks continued. The acquired data were immediately mapped at the on-site restoration headquarters, and the extent of the damage was rapidly shared. As a result, the lead time to drafting restoration plans was greatly reduced, enabling earlier commencement of restoration work. In addition, because municipal staff could perform measurements of damage themselves—tasks that had previously been outsourced to surveying companies—this contributed to a reduction in external contracting costs and the internalization of technical expertise. This is a case where rapid situation assessment and information sharing through single-person surveying made a major contribution to speeding up life-saving operations and infrastructure restoration.

Case Study 2: Single-person Volume Measurement at a Landslide Disaster Site

Overview: Even at landslide sites caused by intense downpours, one-person surveying is proving effective. In one heavy-rain disaster, a surveyor inspected a mountainside buried by collapsed debris alone. While remaining in a safe position, they walked around 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 debris and from that data immediately calculated the volume of the collapsed soil (volume).

Effect: Whereas such situations traditionally required multiple people to take dangerous measurements and then calculate earthwork volumes after returning with the data, with LRTK you can measure on site and complete the calculations immediately. Having immediate access to volume information of the soil and sediment allowed them to accurately determine the required heavy machinery and number of dump trucks, making the organization of restoration work smoother. Because measurements can be performed by a single person, there is no need to arrange additional personnel, and unnecessary site entry is avoided, which also improves safety. As a result, this is a good example of speeding up the initial disaster response while also ensuring worker safety.

Case Study 3: Quantity Management Using Point Cloud Scanning at an Earthwork Site

Summary: In civil engineering works (land development, embankment, and excavation), surveying to accurately determine as-built conditions and earth volumes tends to be time-consuming. At a certain medium-scale earthworks site, they achieved a significant reduction in labor through a mobile scan using LRTK. A single operator walked around the site holding an LRTK mounted on an iPhone, collecting LiDAR point cloud data of the ground surface. For example, for a development site of about 50 m (164.0 ft) square, a scan operation of just about 5 minutes was enough to obtain point cloud data consisting of several hundred thousand points representing the terrain shape.

Effect: This method has dramatically shortened processes that used to require manually surveying measurement points one by one. Measurements around batter boards and earthwork quantity checks that used to take days can now be completed on the spot. Because the acquired point clouds already have absolute coordinates from the start, there is no need to perform alignment after returning to the office. By comparing point cloud datasets, the volumes of fills and excavations can be calculated instantly, allowing earthwork quantity management and as-built inspections to be carried out in real time. The amount of information and speed obtainable by a single worker increased so much that site personnel were surprised, saying it felt like the workforce had doubled. This is a case that achieved both construction management efficiency and shortened construction schedules.

Case 4: Solo layout on steep slopes and bedrock (AR stake driving)

Overview: Establishing reference lines and marking stake positions (sumi-dashi) for structures is normally a laborious task performed by two or more people. It was particularly difficult to set out positions on bedrock or steep slopes, where wooden stakes cannot be driven. At a tunnel road construction site, they attempted to indicate stake positions alone by utilizing LRTK and AR technology. They registered the coordinate data from the design drawings in the LRTK cloud, and when viewed on site through a smartphone camera, virtual stake markers are displayed in AR on the screen. Workers were able to use those as references to accurately identify points even on hard ground where physical stakes could not be driven.

Effect: With this AR staking, the positioning work that previously required a surveying team to go back and forth could be performed continuously by a single person. By simply moving to the next placement position displayed on the smartphone screen, they can sequentially mark stake points. As a result, stake layout over a wide area could be completed in a short time, and personnel were reduced. Especially in locations with poor footing, no assistant is required, so safety has also improved. In addition, in response to on-site instructions like “we want to place a stake here,” it is possible to measure the coordinates on the spot → immediately display them in AR, creating flexibility to instantly share the site supervisor’s intent. One-person surveying × AR is a good example of achieving both a significant reduction in surveying work effort and an improvement in accuracy.

Case Study 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 completed image to all stakeholders using only paper drawings. Therefore, at a road construction site, a tablet (iPad) equipped with LRTK was used in meetings to overlay the design 3D model onto the real site scenery in AR. By superimposing the planned embankment shapes and structural models onto the actual terrain, everyone—from the client and construction staff to heavy equipment operators and nearby residents—could intuitively grasp the completed appearance.

Effect: The sight of the completed model appearing on-site through a tablet screen deepened stakeholders' understanding and facilitated smoother communication. What had conventionally been explained by pointing at drawings can now be shared on-site simply by "viewing" the model, reducing rework caused by misalignments in understanding. At one site, this approach made communication among construction personnel markedly smoother, and there are reports that mistakes in sharing design intent decreased. Also, by overlaying design data and the constructed work on a tablet during as-built inspections, it became possible to discover deficiencies on the spot and correct them. AR-based "visualization of the site" supported consensus building and quality control, leading to improvements in productivity and construction quality.

Case Study 6: High-Precision Location Recording and Cloud Sharing for Road and Bridge Inspections

概要: In inspections of infrastructure such as roads and bridges managed by municipalities, accurately recording the locations of anomalies is the key to maintenance management. Traditionally, inspection results were managed in paper ledgers and photographs, and there were cases where vague descriptions such as "streetlight failure near 50 m (164.0 ft) east of the ○○ intersection" were relied upon. To improve this, one city introduced a system in which maintenance inspectors photograph and survey defect locations with LRTK-equipped smartphones and share the data. When an inspector finds a streetlight bulb out, simply taking a photo with the smartphone results in the latitude, longitude, and the date/time being tagged, and the data is automatically uploaded to the cloud.

Effect: From the office, staff can view the photo sent and the plot on the map and instantly grasp the exact location and situation. For example, in the past they sometimes had to search around the site after hearing that “a streetlight near XX is out,” but by navigating using the coordinates obtained with LRTK they can reach the site in one go. As a result, repair crews can go straight to the site without wasted effort, and response speed has improved dramatically. In addition, the accumulated high-precision position data is useful for the long-term monitoring of infrastructure assets. If the same bridge pier is measured with LRTK every year and the coordinates are compared, long-term subsidence and displacement can be detected on the order of several centimeters (a few in). What had been subjective anomaly detection based on individual judgment has been transformed into an objective, data-based evaluation, and the accuracy and efficiency of maintenance and management have improved. By incorporating a one-smartphone-per-person surveying tool into inspection operations, field information is shared in real time and with accuracy, leading to the smartization of infrastructure preservation.

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

Overview: Cities have various facilities such as streetlights, traffic signals, fire hydrants, benches, and park playground equipment scattered around, but some municipalities face the challenge of digitizing the precise location data of these. For equipment that has been in place for a long time, coordinate information may be unorganized or only paper drawings may exist. Therefore, one city launched a project in which staff used LRTK to conduct a citywide survey of road signs and update the location registry. Staff approached each signpost one by one and measured the installation location coordinates by pressing a button on a smartphone. They also entered attribute information such as management number and type, and aggregated the data in the cloud.

Effect: This initiative produced a complete latitude-and-longitude list of all signs with accuracy on the order of several centimeters (a few inches), enabling a digital understanding of the current placement of urban assets. Managing installation and removal histories in the cloud also streamlines planning for future equipment renewal. For example, during road construction, knowing the exact locations of buried objects and signs in advance reduces the risk of damage during excavation and improves safety. Likewise, when facilities are damaged by large-scale disasters or traffic accidents, the damaged locations can be immediately identified on a map, aiding rapid response. Using AR functionality, it is also possible to overlay the positions of underground pipes and cables onto the scene viewed through a camera on site, which can be applied to pre-excavation checks. By steadily building up 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 not out of reach. This is a case where diligent ledger maintenance, carried out bit by bit using single-person surveying, contributed to building the foundation for a smart city.

Case 8: Patrol Inspections and Smart Management of Agricultural Irrigation Channels

Overview: The benefits of one-person surveying are now appearing in rural areas as well. At the agricultural affairs department of a local government, LRTK was introduced for the wide-ranging inspection of agricultural waterways and irrigation ponds. Many agricultural civil engineering structures have been in use for decades and may lack accurate positional or shape data. Staff members patrolled along waterways and embankments with an LRTK-equipped smartphone in hand; whenever they discovered cracks or leaks, they photographed them, measured their locations, and recorded them in the cloud.

Effect: As a result, facility management that had previously relied on staff experience and intuition has become data-driven. By reviewing geotagged photos stored in the cloud from the office, repair priorities and work schedules can be rationally planned. For example, if the data clearly shows that "there was also a leak at the same location the previous year," focused reinforcement measures can be taken. Also, when waterways are damaged by heavy rain or earthquakes, the exact coordinates of damaged locations can be recorded and shared immediately, speeding up the preparation of materials for subsidy applications and requests for assistance. This is an example of improving the level of maintenance and management of agricultural infrastructure dispersed over a wide area by enabling efficient patrols and records with LRTK even with a limited number of personnel. Patrol inspections that had been done with paper maps and notebooks have been digitized, and easier information sharing among staff has made stable facility management possible even as generations change.

Case Study 9: Streamlining Boundary Surveys and Stake Position Verification

Overview: Single-person surveying tools are also useful in the work of private surveyors and land and house surveyors. For example, in boundary verification work it was often time-consuming to relocate boundary stakes and survey points placed in the past. When they are hidden by vegetation or when the person on site is different from the previous worker and does not know the reference positions, you end up searching around the site. Therefore, one surveying office registered known boundary coordinates in the LRTK cloud in advance and introduced a method to locate stakes on site using the coordinate navigation function. Going to the site with a smartphone and selecting the target boundary point causes an arrow and distance to be displayed on the screen in real time. Simply following it will guide you pinpoint to the stake location within an error range of a few centimeters (cm level accuracy (half-inch accuracy)).

Effect: With this method, boundary stakes and survey markers can be revisited quickly without losing sight of them. It is especially effective for repeated fixed-point observations and field surveys carried out at long intervals, as it makes it easy to reproduce the exact point measured previously. As a result, the time spent on boundary verification has been greatly reduced and survey efficiency has improved. Also, because photos and notes of boundary markers taken previously can be reviewed in chronological order within the LRTK app, it helps with checking changes over time and preventing oversights. By enabling complete boundary surveys single-handedly, small surveying firms can handle many projects in parallel and improve their response speed to clients. The solo surveying tool that improves efficiency without sacrificing accuracy is a powerful ally in both public and private surveying environments.

Case 10: Safe surveying using non-contact positioning indoors and at height

概要: LRTK can be adapted through creative measures not only for outdoor use but also for measurements beneath structures where GPS is difficult to receive and at elevated locations. For example, in places where GNSS signals are normally not receivable, such as under bridge girders or inside tunnels, LRTK's indoor positioning mode is effective. Once the current position is acquired as a reference at a location where GPS can be received, even after entering an area outside GPS coverage it computes relative positions using inertial navigation and continues to enable positioning with cm level accuracy (half-inch accuracy). In fact, in a case where LRTK was used for under-bridge inspection, acquiring measurement points by going under a bridge pier was safely completed by a single person.

For measuring high points that are out of reach, LRTK's target positioning function (non-contact positioning) is useful. For example, if you want to measure the coordinates of bolts located at the top of a slope or in a high position on a bridge, 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—without forcibly extending a pole or having someone climb up.

During an inspection of a plant facility, valve mounting positions were photogrammetrically positioned from the ground, allowing the coordinates needed for drawing revisions to be obtained without deploying an aerial work platform.

Effect: These functions have made it possible to acquire data from places that previously could not be measured and to reduce labor for hazardous work at height. In surveying under bridges, there is no need to erect temporary scaffolding or have multiple people lean in, yielding significant benefits in terms of safety and cost. With non-contact positioning capabilities, accurate positional information can be obtained during inspections of equipment located at elevated positions without using tape measures or step ladders, which leads not only to reductions in work time and effort but also to reduced risk for workers. One-person surveying tools are a prime example of turning locations that were difficult to measure into accessible ones, thereby expanding the scope of on-site work.

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

That concludes our introduction of ten on-site case examples using LRTK. You may have thought, "Can you really do this much with one-person surveying?!" With the advent of LRTK, surveying work is transforming from the exclusive preserve of experienced veterans into an everyday tool that anyone can use. If you bring nothing more than a smartphone and LRTK to the site, high-precision surveying, inspection records, photography, and data sharing can all be completed in no time.

The advantages of one-person surveying, put simply, are dramatic improvements in productivity and safety. Because it can acquire the necessary and sufficient survey data with a small crew and in a short time, the burden of personnel coordination and on-site time is reduced, allowing those resources to be allocated to other tasks. Direct effects such as reduced labor costs and shortened project schedules also contribute to cost management for companies and municipalities. In addition, because tasks can be completed by a single person, it helps avoid "close-contact" situations and is therefore well suited to the non-contact and remote measures that attracted attention during the COVID-19 pandemic.

Even in terms of Accuracy and Quality Assurance, solo surveying excels. Tools like LRTK automatically guide and record via an app, reducing the risk of human error. Young staff can take accurate measurements without relying on the intuition of experienced workers, which alleviates concerns about skill transfer. Because data measured on-site can be checked and shared in real time, this also enables early detection of mistakes and helps prevent rework. In short, solo surveying is bringing the on-site ideal of "fast, cheap, safe, and accurate" much closer.

Furthermore, in recent years national and local government support measures for digitalization have been strengthened. There are cases where subsidies can be used to introduce high-precision GNSS equipment, and programs that encourage equipment procurement as part of efforts to strengthen disaster response capabilities can also be seen. Even small and medium-sized enterprises and municipalities that have been hesitant to adopt such systems due to high costs can realistically implement cost-effective solutions like LRTK.

The new style of one-person surveying is poised to bring major transformations not only to the surveying and construction industries but also to the maintenance and management of infrastructure across society. Using LRTK, a smartphone becomes "the eyes and feet on site", enabling on-site conditions to be recorded and shared digitally exactly as they are. This is precisely the driving force behind on-site DX and can also be seen as part of work-style reform.

Finally, if in your workplace or project you feel that "surveying takes too much manpower and time" or you want to "collect site information more efficiently," please consider single-person surveying with LRTK. By adopting this technology, which combines ease of use with high accuracy, the barriers to surveying will be dramatically lowered and the possibilities on site will expand. Its intuitive operability means it can be handled even by non-experts and will be immediately effective from the moment of introduction. The time and flexibility gained through single-person surveying can surely be redirected to other value-creating activities. Why not take your site to the next stage with the new surveying style made possible by LRTK?