"LRTK" — A Single-Operator Surveying Device That Balances Accuracy and Efficiency

Labor Shortages and Productivity Challenges at Surveying Sites

Surveying work is indispensable at construction and civil engineering sites. However, in recent years, the situation has become critical as labor shortages and the aging of skilled technicians force limited personnel to cover many sites. Surveying, which used to commonly be done by a team of two (or sometimes three), is increasingly expected to move toward "single-operator surveying", meaning tasks completed by just one person. Reducing personnel lowers labor costs and makes schedule coordination easier, making this approach highly attractive to an industry chronically short of workers.

However, traditional surveying methods also hide productivity issues. For example, measuring hundreds of points on a large development site can easily take a team a full day. Even after finishing fieldwork, office tasks such as plotting points on drawings, calculating quantities, and preparing reports remain. The inefficiency of shuttling between the field and the office and spending time organizing data is inevitable.

The risk of human error is also a major problem. Mistakes such as writing numbers incorrectly in handwritten notes or forgetting to attach location data to photos can cause rework and affect project schedules. Operating advanced surveying instruments requires specialized skills, so work tends to rely on experienced veterans; if they are absent, tasks can be stopped while waiting for surveying to be done. In short, surveying sites facing staff shortages, inefficient workflows, and error risks need methods that allow one person to measure accurately and efficiently.

What Is Single-Operator Surveying? Benefits and Challenges of Traditional Methods

"Single-operator surveying" literally refers to surveying performed by one person. Traditionally, surveying required two people: one to operate the instrument and another to set targets at observation points. For example, when using a total station, one person looks through the instrument to measure angles while another stands at a distant point holding a prism. Single-operator surveying eliminates the need for someone to remain with the instrument, allowing such staffing to be greatly simplified.

The biggest advantage of single-operator surveying is, of course, cost reduction and efficiency by halving the necessary workforce. If one person can manage the task, it becomes easier to secure personnel and coordinate schedules, and cumbersome communication like shouting in noisy environments becomes unnecessary. With fewer staff, consistent surveying becomes easier to maintain, even at sites lacking skilled workers. Overall lead times for surveying can be shortened, speeding up the entire process.

On the other hand, traditional single-operator solutions had challenges. Technologies that allowed one person to operate—such as auto-tracking total stations or high-performance laser scanners—were expensive, large, and required training. They could not measure where sight lines were blocked, and carrying heavy equipment was a burden. In other words, simply being able to be operated by one person was not enough for true efficiency; further technological innovation was needed to reduce labor from setup through post-processing.

Evolution of Single-Operator Surveying Driven by Technological Innovation

Recent advances in digital technology have pushed single-operator surveying to a new stage of evolution. Particularly noteworthy is the new approach combining smartphones with high-precision GNSS (Global Navigation Satellite Systems). By pairing an ordinary smartphone with a centimeter-level GNSS receiver, surveying work that previously required multiple people is becoming feasible for a single operator.

The appeal of this "smartphone surveying" goes beyond merely reducing personnel. Using GNSS enables surveying in locations without line-of-sight and makes efficient measurement of wide areas or multiple distant points possible. In environments with cellular coverage, correction data can be received via the smartphone to obtain high-precision absolute coordinates immediately. Smartphone apps also automate data recording and processing, reducing mistakes from handwritten notes and office transcription. If data are shared to the cloud on site, stakeholders can confirm results without returning to the office, accelerating decision-making.

Furthermore, the application of AR (augmented reality) to surveying has recently emerged. Overlaying survey data and design models on the smartphone’s camera view allows intuitive on-site positioning and verification. For example, showing a virtual stake at a design location for on-site confirmation or guiding re-photography to match a past viewpoint via AR greatly expands the usability of survey data.

Thanks to these innovations, single-operator surveying has reached a new level that does not compromise on accuracy or efficiency. A representative solution of this approach is the smartphone-mounted compact surveying device "LRTK".

What Is LRTK? Its Structure and Features

LRTK is a compact RTK-GNSS device for single-operator surveying developed by a startup originating from the Tokyo Institute of Technology. It has a simple structure consisting of a dedicated smartphone case (or magnetic holder) and a thin GNSS receiver that attaches and detaches with a single touch. Attach the LRTK receiver to the back of an iPhone or iPad and connect via Bluetooth or Lightning, and you are ready to go. By mounting a receiver that weighs only about 125 g (approximately 13 mm thick), an ordinary smartphone quickly becomes a surveying device capable of centimeter-level accuracy.

LRTK includes a high-performance antenna and built-in battery, allowing several hours of continuous use. Where traditional GNSS equipment and total stations weighing several kilograms and requiring tripods were used, LRTK and a smartphone in the palm of your hand can substitute, dramatically reducing the burden of bringing equipment to the site. The portability of carrying it in a pocket and taking it out when needed is a major advantage not found in conventional surveying instruments.

The operation uses an intuitive UI typical of smartphone apps, designed so people without specialist knowledge can handle it. Point the device at the location you want to measure and press a button to start positioning. When measurement is complete, latitude, longitude, and elevation are recorded automatically. The app also allows saving point names, timestamps, and notes, eliminating the need for paper field notebooks. Acquired coordinates are converted in real time into the Japanese geodetic system’s plane coordinates and elevations (including geoid heights), saving surveyors the trouble of post-measurement coordinate transformations. Designed with one device per person in mind, the system enables anyone on site to use a personal surveying device easily.

LRTK’s Technology for Balancing Accuracy and Efficiency (RTK-GNSS, CLAS, AR Features)

LRTK can deliver both high accuracy and high efficiency by combining cutting-edge technologies. First and foremost is support for RTK-GNSS positioning. RTK (Real-Time Kinematic) compares satellite data received at the roving unit (LRTK) and a reference station in real time to correct error sources, dramatically improving positioning accuracy. While typical smartphone GPS error is on the order of meters, LRTK using RTK can obtain position coordinates corrected to below several centimeters. This ensures the positioning accuracy required for tasks demanding high precision, such as boundary layout and as-built measurements, can be handled by a single operator.

Correction information is essential for RTK, and LRTK is designed for nationwide operation by supporting multiple correction sources. These include network RTK using the electronic reference station network operated by the Geospatial Information Authority of Japan (via the Ntrip protocol), and CLAS—the free centimeter-level augmentation service provided by Japan’s Quasi-Zenith Satellite System, MICHIBIKI. In urban and plain areas with cellular coverage, correction data can be received from the internet via Ntrip; in remote mountainous areas or disaster sites far from base stations, if the sky is open, CLAS signals from MICHIBIKI can be received directly to achieve real-time centimeter-level correction. These mechanisms allow LRTK to provide instant centimeter-level positioning nationwide without installing dedicated base stations.

The LRTK app includes various digital functions to streamline surveying. Acquired positioning data can be uploaded to the cloud with one tap, allowing immediate verification from office PCs. Points measured in the field are plotted on maps and their coordinates and notes can be shared with stakeholders, so survey results can be put to use in the next steps right away. Distance and area measurement functions are also available, making it easy to automatically calculate necessary values from on-site coordinate data.

A major feature of LRTK is its AR support. The AR staking function can display virtual stakes and lines on the site through the smartphone screen, enabling accurate positioning work by a single person. Input target coordinates from the design into the app and it will display arrows and distances to the target point on the screen; following this guidance by walking leads you to the designated location. Switching to the camera view projects virtual objects (stakes or markings) onto the site imagery so you can verify the target as if it were physically there. Staking work that traditionally required an assistant calling out positions can now be performed accurately and without confusion by one person using LRTK’s AR navigation. Even on slopes or in locations inaccessible for direct entry, AR displays allow checking points or simulating staking from a safe distance, contributing to improved safety.

Portability, Usability, and Ease of Use of LRTK in the Field

LRTK is designed for field use with a focus on portability and operability. As noted, the device itself fits in a pocket, so carrying it is not a burden. This creates the mobility to "use it whenever surveying is needed." Without carrying tripods and heavy equipment, surveying can begin immediately upon arrival, which is a major advantage. Even when continuously taking points while moving, there is no need to set up equipment repeatedly—simply walking with a smartphone efficiently collects data.

The smartphone app’s UI prioritizes intuitive on-site operation. Positioning start and stop can be controlled with a single button, and necessary information is displayed clearly. For example, when measuring multiple points consecutively, the app auto-numbers point names, eliminating the need for manual naming. All recorded data are saved automatically after measurement, so there is no need to transcribe to paper. The device is robustly designed with dust and water resistance, allowing safe use outdoors where there may be soil or rain.

Moreover, LRTK’s low entry barriers make it attractive. Conventional high-precision GNSS equipment cost hundreds of thousands of dollars per unit, whereas LRTK is offered at an overwhelmingly affordable price range of tens to hundreds of thousands of yen (the dedicated app is available for free). This makes it realistic for each field staff member to own their own LRTK. By overturning the conventional wisdom of "one surveying instrument per team," LRTK is designed with one device per person cost considerations. Using free correction services like CLAS also keeps operating costs down, making adoption easier for small and medium-sized enterprises and local governments.

Case Studies of Site Improvement Following LRTK Introduction

Sites that have actually introduced LRTK report significant efficiency gains and cost reductions. At one civil engineering site, an as-built measurement that previously required two people and a full day was completed by one person in a few hours after adopting LRTK. This case achieved a more than 70% reduction in working time, directly freeing staff time and reducing labor costs. Shorter surveying lead times allowed subsequent construction steps to be moved forward, contributing to overall project schedule reductions.

Local governments are also starting to adopt LRTK. For example, one city hall quickly adopted LRTK for post-disaster damage surveys. Staff could immediately measure and record damaged locations on site with a smartphone, eliminating the need for multiple trips between the office and the field. As a result, detailed digital damage records were completed more quickly than before, shortening the period required to develop recovery plans. This on-the-spot responsiveness is another major strength of single-operator surveying.

A small construction company that adopted LRTK was able to bring as-built management—previously outsourced to surveying firms—back in-house. By performing surveying themselves, they achieved cost reductions and began accumulating know-how internally. These success stories demonstrate the effectiveness of single-operator surveying and highlight its role in the industry’s digital transformation (DX).

Concrete Surveying Steps Achievable with LRTK

Finally, imagine the basic workflow for one-person surveying using LRTK. The following steps show how field surveying can be completed simply and quickly.

• Preparation and setup: Upon arriving at the survey point, attach the LRTK receiver to your smartphone and power it on. Launch the app and confirm that GNSS satellites are being received—then you’re ready (connect to a correction service if necessary; auto-connect settings are available).

• Acquiring survey points: Move to the location to be measured, place the tip of the device (a stylus-like tip can be attached) on the point, and tap the app’s "Start Positioning" button. The app will perform a high-precision coordinate measurement for that point. During positioning, satellite reception status and accuracy indicators are displayed, and results stabilize in a few to several seconds.

• Data recording: After measurement, tap "Save" in the app to record the coordinate data. Point names and timestamps are recorded automatically, and you can add notes as needed. Measured coordinates are converted in real time to plane rectangular coordinates and elevations and displayed on the screen. No additional calculations or handwritten records are required.

• Cloud sharing: After obtaining all necessary points, upload the data to the cloud with one click. Data can be viewed immediately from office PCs or other devices over the internet, allowing supervisors and colleagues to review results on the spot and provide checks or instructions for the next steps smoothly.

• Positioning and staking (using AR): If staking based on measured points or design coordinates is required, LRTK excels. Select target coordinates in the app’s navigation feature and it will display guidance such as "move XX direction by YY cm," so simply following the guidance leads you to the designated location. Switching to the camera view displays a virtual stake at the target point (AR staking). Using this AR reference to mark the site enables even first-time users to stake accurately without confusion.

• Verification of results: After surveying, verify acquired points on the cloud map and easily calculate distances or areas between points to obtain the required deliverables. There is no need to replot on paper; digital data can be imported into various software tools for further use. If additional on-site measurements are needed, having a smartphone and LRTK on hand allows immediate response.

With these steps, surveying and plotting processes that used to take days can be completed the same day using LRTK. The seamless connection from point acquisition to staking—and the fact that all of it can be done by one person—can be considered revolutionary.

Message to Those Considering Adoption

LRTK, which enables single-operator surveying, is a practical solution to the challenge of balancing surveying accuracy and operational efficiency. In an industry struggling with chronic labor shortages, the benefits of one-person surveying—reducing manpower while maintaining quality—are invaluable. By adopting LRTK, you can reduce interruptions caused by "waiting for surveying," and strongly promote DX on site. Making advanced surveying technology operable by anyone on site means that knowledge can be shared across the organization without relying solely on veterans.

The single-operator surveying device LRTK, which achieves both accuracy and efficiency, is already delivering results at sites across the country. As adoption expands, the way surveying is conducted will fundamentally change and significantly contribute to productivity improvements in construction sites. If you are currently facing challenges in streamlining or improving the efficiency of surveying operations, consider the new surveying style enabled by LRTK. Experience the expanded possibilities of measurement with just a smartphone and a small device, and seize the opportunity to evolve your site to the next stage.