What are the strengths of LRTK that lead the forefront of one-man surveying?

In recent years, a new style in the surveying world called "one-man surveying" has been attracting attention. This method, which allows a single person to complete surveying tasks, is expected to be a solution to challenges faced by the construction and surveying industries such as labor shortages and an aging workforce. Advances in technology—such as robotic total stations and high-precision GNSS positioning—have made it possible for surveying that once required multiple people to be performed by a single operator.

Leading the forefront of this one-man surveying movement is LRTK, a compact positioning device developed by Lefixea Inc., a startup originating from Tokyo Institute of Technology. LRTK (pronounced “el-are-tee-kay”), which enables centimeter-level precise positioning simply by attaching it to a smartphone, is driving DX (digital transformation) on job sites and making solo surveying a reality. This article explains in detail why LRTK can lead the industry in one-man surveying and what its key strengths are.

Background driving demand for one-man surveying

Traditionally, surveying work was performed by multi-person teams. For example, with a total station (TS), one person operates the instrument while another stands at a distant survey point holding a prism. A pair of a skilled surveyor and an assistant, sometimes with a recorder making a three-person team, was the norm, and on large sites it was not uncommon for the team to spend an entire day on tasks. Naturally, labor and time costs were significant, and administrative work such as data processing and drawing creation remained after fieldwork. Under these conventional methods, sites suffering from personnel shortages bore a particularly heavy burden and faced barriers to efficiency.

However, in recent years, amid population decline and a shortage of skilled workers, the challenge of “how to operate job sites efficiently with fewer people” has grown, and expectations for one-man surveying have increased. Technological innovation is part of this trend. The advent of automatic-tracking robotic total stations made it possible for one person to track targets and measure. In addition, advances in GNSS (satellite positioning) technology, particularly the spread of real-time kinematic (RTK) methods, now allow centimeter-level high-precision positioning by a single operator using correction information from base stations. National promotion of *i-Construction* and DX in the construction industry have also supported this shift, and the idea that “if one person can measure it, that’s preferable” is gradually taking hold on job sites.

What is LRTK? A smartphone positioning device that enables solo surveying

LRTK is an ultra-compact RTK-GNSS receiver used in combination with a smartphone. A device weighing approximately 165g and about 1 cm (0.4 in) thick is attached to the back of an iPhone or similar device and connected to the smartphone via Bluetooth or Lightning, instantly turning the handheld phone into a centimeter-level surveying instrument. Inside it contains a high-performance GNSS antenna and a battery; it operates by receiving power and control from the smartphone. With only a pocketable device and a smartphone, positioning work that used to require tripods and multiple people can now be completed by one person. It is truly a groundbreaking solution that opens the era of “smartphone surveying.”

The LRTK system supports network RTK and augmentation signals from Japan’s Quasi-Zenith Satellite System, enabling real-time high-precision positioning anywhere in the country. In addition to the Ntrip method for receiving correction data from base stations via mobile networks, it can obtain correction information directly from satellites (the QZSS CLAS signal) in areas where network connectivity is difficult, correcting errors down to several centimeters.

Despite its simple, smartphone-friendly design, the LRTK device is equipped with a battery that can endure several hours of continuous measurement. Bringing only an iPhone and an LRTK to the field allows you to start high-precision one-man surveying immediately. Positioning accuracy is in a different league from conventional smartphone built-in GPS: using LRTK can achieve errors within a few centimeters (within a few inches), a level adequate for surveying work.

Main strengths that make LRTK lead the forefront

LRTK attracts attention at the forefront of one-man surveying because of many strengths in functionality and usability. Here are the main points.

• Centimeter-level high-precision positioning: RTK GNSS positioning can increase positioning accuracy to errors of a few centimeters (a few inches). While typical smartphone built-in GPS has errors around 5–10 m (16.4–32.8 ft), LRTK can secure the accuracy required for surveying even when operated by a single person. With high-precision location information, it can be reliably used for as-built verification and layout marking.

• Pile-driving support with AR navigation: LRTK’s dedicated smartphone app includes a coordinate navigation function using AR technology. For pre-set target point coordinates, the screen displays in real time instructions like “move east by ○ cm” or “move north by ○ cm” from your current position, so a single operator can perform stakeout (layout) tasks accurately without getting lost. Traditional multi-person layout work can be completed solo with just a smartphone in hand.

• 3D surveying in cooperation with LiDAR: By linking with an iPhone’s LiDAR sensor and camera, you can easily scan the surroundings to acquire three-dimensional point cloud data. Because LRTK can attach high-precision coordinates to each point during scanning, you can measure wide areas of terrain and structures by walking around with the smartphone held up. Details that were overlooked in traditional spot-check surveys are recorded in the point cloud, aiding as-built confirmation and digital twin construction.

• Automatic recording of positioning data and photos: With a tap of the measurement button, latitude, longitude, and elevation at that moment are automatically saved with a timestamp. Survey point names are auto-numbered and listed, eliminating the need to transcribe into field notebooks. Photos taken with the smartphone are automatically linked with positioning information. Being able to record site conditions with photos shortens data processing time and reduces human error.

• Immediate data utilization through cloud sharing: Survey data acquired on site can be uploaded to the cloud and shared with stakeholders on the spot. If you send the result data from your smartphone immediately after measuring, your supervisors and colleagues can be reviewing it by the time you return to the office. Since coordinates and point clouds can be viewed and utilized instantly in the cloud, any missed measurements can be reported back for immediate re-measurement on site. This minimizes rework and contributes to lead-time reduction.

• Intuitive operation by leveraging smartphones: Setup is as simple as attaching the LRTK device to your smartphone. No complicated initial configuration is required, and even at a first-time site it takes only a few dozen seconds from power-on to obtaining an RTK “FIX” solution. The dedicated app’s interface is simple and easy to understand, allowing even technicians with limited experience using specialized equipment to operate it intuitively. From young workers accustomed to smartphones to veterans, anyone can master it with short training, enabling smooth adoption on sites.

• Low-cost and easy to introduce: Low introduction cost is another major attraction of LRTK. Conventional high-precision GNSS survey systems with integrated antennas typically cost several million yen per unit, but a pocket-sized LRTK device is priced in the tens of thousands to low hundreds of thousands of yen range, making it drastically more affordable. The dedicated app is provided free, and existing smartphones can be used so no new dedicated terminals are necessary. There are communication fees when using high-precision positioning services, but overall initial investment and running costs are greatly reduced compared to conventional equipment. This price range makes it easy for small and medium-sized enterprises and local governments to adopt, allowing them to enjoy the benefits of improved accuracy and efficiency at low cost—another reason LRTK is chosen.

Simple steps for one-man surveying with LRTK

One-man surveying with LRTK can be started easily by anyone using the following steps.

• Prepare the device and app: First, prepare the LRTK device and attach it to the smartphone you will use (iPhone/iPad, etc.) with a dedicated holder or case. Download and install the free “LRTK” dedicated app from the App Store or Google Play in advance.

• On-site setup: Upon arrival at the survey site, turn on the LRTK device attached to the smartphone. Launch the LRTK app and connect to the device; satellite acquisition will begin and RTK positioning will start. After waiting several dozen seconds until the app displays an RTK “FIX” solution (the high-precision positioning state), you are ready to measure.

• Execute positioning and measurement: Move to the point you want to measure and simply tap the “Measure” button in the app to record the high-precision coordinates of that location. No assistant is required. If you want to continuously measure a wide area, just walk while holding the smartphone and automatic point cloud scanning will occur, generating a surrounding 3D model. For layout tasks like stakeout, use the coordinate navigation function and follow the on-screen directions to accurately mark target positions solo.

• Data verification and sharing: Measured coordinate data and generated point clouds are displayed instantly in the app, and distance and area calculations can be performed on the spot. If desired, take photos on site and save them as record photos with positioning information. After finishing work, upload data to the cloud with one tap from the app so that stakeholders can already be sharing the results by the time you return to the office. Because you can receive additional instructions or re-measure requests immediately, you can complete surveying tasks efficiently and reliably.

Major benefits gained by introducing LRTK

The benefits that one-man surveying with LRTK brings to job sites include the following points.

• Labor savings and reduced personnel costs: Surveying that previously required 2–3 people can be performed by one person, helping to resolve manpower shortages and significantly reducing labor costs. Limited personnel can cover multiple sites, directly increasing productivity.

• Shorter work times: Fast positioning and data processing dramatically reduce lead times from surveying to drawing creation, quantity calculation, and reporting. Because field data can be immediately shared in the cloud and reviewed, as-built confirmation work that used to take several days can be completed within the same day.

• Improved surveying accuracy and data quality: RTK-GNSS enables measurements with centimeter-level accuracy, allowing acquisition of data that meets precision requirements. Point cloud measurement enables high-density measurement of the entire site, producing comprehensive, high-quality deliverables without omissions. With smaller errors, re-measurement and rework are also reduced.

• Improved safety: Shorter surveying time on site reduces workers’ time in the field, lowering risks of heatstroke and accidents. Nighttime surveying or work on roads with heavy traffic can be completed in shorter time, reducing exposure to hazardous situations.

• Reduction of human error: Because measurements and photos are digitally recorded automatically, mistakes from handwritten notes or data transcription are eliminated. Missed measurements and record omissions can be prevented, enabling more reliable deliverables.

• Easier skill acquisition and reduced dependence on individuals: Smartphone-app-centered operation is easy to understand and can be learned in a short period. Surveying know-how is systematized, allowing work to be performed at a consistent level without relying on specific veterans. Work is less affected by individual experience, enabling stable surveying across the organization.

Proven efficiency and quality improvements on sites

The effects of introducing LRTK have already been demonstrated on job sites. For example, at a certain civil engineering site, the introduction of LRTK reported major efficiency gains in surveying. Where as-built measurement used to take a full day with two people, after introducing LRTK one person completed the task in several hours, achieving about a 70% or greater reduction in work time. Labor costs were also significantly reduced, and because LRTK enabled real-time acquisition of high-density survey data, the entire site was measured comprehensively, improving accuracy and quality. Thanks to the detailed point cloud data acquired, areas that were overlooked in traditional spot-check surveys could be verified, contributing to early detection of construction errors and prevention of rework.

Local governments have also begun utilizing LRTK for DX in on-site surveying. For example, Fukui City was quick to introduce the LRTK system in 2023 for on-site disaster recovery surveys. Because staff can start smartphone surveying immediately upon discovering damaged areas, the back-and-forth between the field and the office is reduced and detailed damage records can be created in less time than before. As a result, the lead time from planning recovery to starting construction was shortened, contributing greatly to early recovery and cost reduction. The relatively low introduction cost is also attractive to municipalities, enabling them to perform surveying in-house instead of outsourcing, resulting in cost compression and internalization of technical capability. In this way, one-man surveying using LRTK is steadily producing results in the public sector, and motivated by these outcomes, other municipalities are beginning to consider adopting LRTK.

Conclusion

LRTK is changing conventional wisdom on job sites with a number of strengths that make one-man surveying possible. It enables anyone to handle centimeter-level positioning easily, turning surveying tasks that once required multiple people into remarkably simple operations with LRTK. By allowing one person to efficiently measure sites and immediately share and utilize data, LRTK supports a smart way of working and is a reliable partner leading DX on the front lines. Furthermore, the LRTK series is compatible with the Ministry of Land, Infrastructure, Transport and Tourism’s *i-Construction* initiatives, strongly supporting the digitalization of the construction industry.

Use the high-precision, easy-to-use LRTK to achieve labor savings and improved efficiency at your sites. If you are interested, please visit the [LRTK official site](https://www.lrtk.lefixea.com) and feel free to contact us via the [inquiry form](https://www.lrtk.lefixea.com/contactlrtk). Experience LRTK’s “simple surveying” that starts with just a smartphone and evolve your site to the next stage.