Accuracy × Efficiency Combined One-Man Surveying Device 'LRTK'

Labor shortages and productivity challenges at surveying sites

Surveying is indispensable at construction and civil engineering sites. However, in recent years, the situation has worsened as limited personnel must handle many sites due to labor shortages and the aging of skilled technicians. Surveying, which traditionally required two people working as a pair (and sometimes three), is increasingly expected to shift to "one-man surveying", meaning tasks are completed by a single person. Reducing personnel lowers labor costs and makes scheduling easier, which is highly attractive to an industry chronically short of workers.

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

The risk of human error is also a major problem. Mistakes like miswriting numbers on handwritten notes or forgetting to attach location information to photos can cause rework and delay schedules. Additionally, operating advanced surveying equipment requires specialized skills, so sites tended to rely on experienced veterans; if that person is absent, work often halts while waiting for surveying. In short, surveying sites facing staff shortages, operational inefficiencies, and risk of errors need a way for one person to survey accurately and efficiently.

What is one-man surveying? Advantages and challenges of traditional methods

"One-man surveying" literally means surveying performed by a single person. Traditionally, surveying required two people: one to operate the instrument and one to place targets at observation points. For example, when using a total station, one person looks through the instrument to measure angles while another holds a prism at a distant survey point. One-man surveying simplifies this staffing by allowing work to be done without someone stationed at the surveying instrument.

The biggest advantages of one-man surveying are the cost reductions and improved efficiency from halving the required personnel. If one person can do the job, securing labor and scheduling become easier, and cumbersome communication such as calling out in noisy environments is unnecessary. It also enables consistent surveying with limited staff, making it easier to maintain quality even at sites lacking experienced personnel. Overall lead times for surveying can be shortened, accelerating the entire construction schedule.

On the other hand, traditional one-man surveying had challenges. Existing technologies that allow one-person operation—such as auto-tracking total stations and high-performance laser scanners—are expensive and bulky, requiring training to operate. They also have limitations like being unable to measure where visibility is obstructed and the burden of transporting heavy equipment. In other words, merely being "operable by one person" was not sufficient for true efficiency; further technological innovation was essential to reduce labor from setup through post-processing.

Evolution of one-man surveying supported by technological innovation

Recent advances in digital technology have propelled one-man surveying to a new evolutionary stage. Notably, a new approach combines smartphones with high-precision GNSS (Global Navigation Satellite Systems). By pairing a smartphone everyone carries with a GNSS receiver capable of centimeter-level position measurement (cm level accuracy (half-inch accuracy)), surveying tasks that once required multiple people are becoming completable by a single person.

The benefits of this "smartphone surveying" go beyond merely reducing personnel. Using GNSS enables surveying even in locations without direct line-of-sight and makes it efficient to measure wide areas or multiple distant points simultaneously. Where cellular signal is available, correction information (described later) can be received via the smartphone to obtain high-precision absolute coordinates instantly. Smartphone apps automate data recording and processing, reducing errors from handwritten notes and office transcription work. If data are shared to the cloud on the spot, stakeholders can review results without returning to the office, speeding decision-making.

Moreover, recent efforts have applied AR (augmented reality) to surveying. Overlaying survey data and design models on a smartphone camera view allows intuitive positioning and verification on site. For example, AR can display a virtual stake at a design location for on-site confirmation or guide rephotography from the same viewpoint and angle as a past photo. This greatly expands how survey data are used.

Thanks to these technological advances, one-man surveying has reached a new stage that does not compromise either precision or efficiency. A representative solution is the smartphone-mounted compact surveying device 'LRTK'.

What is LRTK? Its structure and features

LRTK is a compact RTK-GNSS device for one-man 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 can be attached and detached with one touch. By mounting the LRTK receiver on the back of an iPhone or iPad and connecting via Bluetooth or Lightning, setup is complete. Simply attaching the receiver, which weighs about 125 g (thickness about 13 mm (0.51 in)), instantly transforms an ordinary smartphone into a centimeter-level (half-inch accuracy) surveying device.

LRTK contains a high-performance antenna and a battery, allowing several hours of continuous use. Because equipment that once weighed several kilograms—GNSS units or total stations mounted on tripods—can be replaced by a palm-sized LRTK and a single smartphone, the burden of bringing equipment to the site is dramatically reduced. The portability of carrying it in a pocket and taking it out when needed is a major attraction not found in traditional surveying equipment.

Operability is designed with an intuitive UI typical of smartphone apps, making it easy for non-experts to use. Point the device at the location to be measured and press a button to start positioning. When measurement is complete, latitude, longitude, and elevation are recorded automatically. The app also lets users save point names, timestamps, and notes, eliminating the need for paper field books. Acquired coordinates are converted in real time to Japan’s plane coordinate system and elevations (including geoid height), saving surveyors the hassle of later coordinate transformations. Developed with the idea of one device per person, it’s designed so anyone on site can easily use their own surveying device.

LRTK technologies that realize both accuracy and efficiency (RTK-GNSS, CLAS, AR features)

LRTK achieves both high accuracy and high efficiency by combining cutting-edge technologies. First to note is LRTK’s support for RTK-GNSS positioning. RTK (Real-Time Kinematic) compares satellite data received by the rover (LRTK) and a reference station in real time to correct error factors, dramatically improving positioning accuracy. While typical smartphone GPS errors are on the order of several meters (several ft), LRTK’s RTK method corrects positions to errors of a few centimeters or less (a few inches or less). This ensures sufficient positioning accuracy for high-precision tasks such as boundary staking and as-built measurements, even when done by one person.

RTK requires correction information, and LRTK is designed for nationwide operation by supporting multiple correction sources. It supports network RTK via Ntrip using the Geospatial Information Authority of Japan’s continuous operating reference stations, and it is compatible with Japan’s quasi-zenith satellite Michibiki’s free centimeter-class augmentation service CLAS. In urban and plain areas with cellular coverage, correction data can be received over the internet via Ntrip, while in mountainous or disaster areas far from base stations, CLAS signals can be received directly from Michibiki satellites if the sky is open, enabling real-time correction of positioning errors of several centimeters (several inches). Thanks to these mechanisms, LRTK can provide instant centimeter-level positioning anywhere in the country without installing special base stations.

The LRTK app includes various digital features to streamline surveying. Acquired positioning data can be uploaded to the cloud with one tap and immediately checked from the office PC. Measured points are plotted on a map and coordinate values and notes can be shared with stakeholders, allowing survey results to be used immediately in subsequent processes. The app also offers distance and area calculation functions, making it easy to compute required values from on-site coordinates.

A major feature of LRTK is its AR functionality. An AR staking feature displays virtual stakes and lines on the smartphone screen so that a single person can perform accurate positioning tasks. When you input coordinates specified in the design into the app, it displays arrows and distances on the screen to the target point, and you simply follow the guidance to reach the correct location. Switching to the camera view projects virtual objects (stakes or markings) onto the field image, allowing confirmation as if the real object were present. Staking work that used to require a helper to align positions by calling out can now be done accurately and without getting lost by one person using LRTK’s AR navigation. Even on slopes or other locations where direct access is unsafe, AR displays let you check points or simulate staking from a safe distance, contributing to improved safety.

LRTK portability, usability, and field-friendliness

LRTK’s design prioritizes portability and usability for field use. As noted, the device fits in a pocket, so carrying it does not burden workers. This creates the mobility to "use it whenever surveying is needed." Without having to carry a tripod and set up heavy equipment, surveying can begin immediately upon arrival—a major advantage. Even when taking measurements continuously while moving, there is no need to set up equipment each time; you can efficiently collect data just by walking with your smartphone.

The app’s interface emphasizes intuitive field 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 manual naming. After measurements, all recorded data are automatically saved, so there is no need to transcribe to paper. The device is robust with dustproof and waterproof considerations, ensuring reliable use outdoors in rain or muddy conditions.

LRTK also has a low barrier to adoption. Conventional high-precision GNSS equipment cost hundreds of thousands of dollars per unit, but LRTK is offered at a dramatically more affordable price range of tens of thousands to low hundreds of thousands of yen (the dedicated app is available free). This makes it realistic for each field staff member to own their own LRTK. By overturning the old norm of "one surveying device per team," LRTK’s cost design anticipates a one-device-per-person era. Moreover, using free correction services like CLAS helps keep operational costs low, making adoption easier for small and medium enterprises and local governments.

On-site improvements realized by LRTK adoption

Sites that have adopted LRTK report significant efficiency gains and cost reductions. At one civil engineering project, as-built measurements that previously took two people a full day could be completed by one person in a few hours after introducing LRTK. In that case, work time was reduced by over 70%, directly freeing up staff time and reducing labor costs. Shorter surveying lead times allowed subsequent construction stages to be advanced, shortening the overall construction period.

Local governments have also started using LRTK. For example, one municipal office quickly adopted LRTK for post-disaster damage assessments. Staff could immediately survey and record damaged locations with a smartphone on site, eliminating repeated trips between the office and the field. They were able to digitally document detailed damage in less time than before, which shortened the period needed to prepare recovery plans. This on-the-spot responsiveness—light-footedness—is another major strength of one-person surveying.

Additionally, small construction companies that introduced LRTK have been able to complete as-built management in-house rather than outsourcing to external surveying firms. By performing surveys themselves, they achieved cost reductions and accumulated know-how internally. These success stories demonstrate the effectiveness of one-man surveying and highlight it as part of industry-wide DX (digital transformation).

Concrete surveying steps realized with LRTK

Finally, here is an image of the basic flow for one-person surveying using LRTK. The field survey can be completed simply and quickly with the following steps.

• Preparation and setup: Upon arriving at the survey location, attach the LRTK receiver to your smartphone and power it on. Launch the app and confirm GNSS satellite reception—you're ready (connect to correction services as needed; automatic connection settings are available).

• Acquiring a survey point: Move to the position you want to measure and place the tip of the device (a stylus or point attachment can be used) on the survey point. Tap the app’s "Start Positioning" button, and the high-precision coordinates of that point will be measured. 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 if needed. Measured coordinates are converted in real time to Japan’s plane rectangular coordinate system and elevation and displayed on the screen. No additional calculations or handwritten records are necessary.

• Cloud sharing: Once all required points are acquired, upload the data to the cloud with one click from the app. Because data can be viewed immediately from office PCs or other devices via the internet, you can share and review results with supervisors and colleagues on the spot and smoothly request checks or instructions for the next steps.

• Staking and positioning (using AR): When performing staking based on measured points or design coordinates, LRTK excels. Selecting a target coordinate in the app displays guidance such as "move ○○ direction by △△ cm," and you simply follow it to reach the designated position. Switching to the camera view shows a virtual stake at the target location (AR staking). By marking the site with reference to this AR display, even first-time users can stake accurately without getting lost.

• Verification of results: After surveying, you can immediately confirm acquired points on the cloud map, calculate distances and areas between points, and obtain required outputs. There is no need to replot on paper; digital data can be easily imported into various software. If additional measurements are required on site, you can respond immediately if you have your smartphone and LRTK at hand.

With these steps, surveying and drawing processes that once took several days can be completed the same day using LRTK. The seamless workflow from point acquisition to staking, all performed by one person, is revolutionary.

A message for those considering adoption

LRTK, which enables one-man surveying, is a practical solution to the difficult challenge of balancing surveying accuracy and work efficiency. For the construction industry suffering from chronic labor shortages, the benefits of one-person surveying—reducing manpower while maintaining quality—are immense. Adopting LRTK can reduce interruptions from "waiting for surveying" and powerfully promote on-site DX. By making advanced surveying technology usable by anyone on site, it also enables organizations to share know-how across the team without relying solely on veterans.

The one-man surveying device LRTK, which achieves both accuracy and efficiency, is already delivering results at sites across the country. As adoption spreads further, it could fundamentally change how surveying is done and greatly contribute to improving productivity on construction sites. If you are currently facing challenges in reducing labor or improving efficiency in your surveying operations, consider the new surveying style enabled by LRTK. Experience the measurement possibilities that open up with just a smartphone and a small device, and take the chance to evolve your sites to the next stage.