LRTK Drawing Attention in the Surveying Industry｜Making One-Man Surveying Easier

How much would work efficiency improve if a single person could carry out surveying on site? For many years in construction and civil engineering, it was common sense that "surveying work requires at least two people." Typically, one person operates the surveying instrument while another stands at the survey point holding a staff (rod). However, in recent years a new surveying style called one-man surveying—which a single person can complete—has been attracting attention. Amid severe labor shortages and waves of workstyle reform, it is seen as a trump card to run sites efficiently with limited personnel.

In practice, the aging of civil engineering personnel and the decline in new entrants have made securing staff capable of surveying a major on-site challenge. As veteran surveyors retire, there are too few young successors, and it is not uncommon for each staff member to take on multiple sites. In addition, the time overtime regulations under the 2024 workstyle reform-related laws (the so-called "2024 problem") are imminent, increasing the need to carry out surveying work efficiently with limited time and personnel. Against this backdrop, one-man surveying, which allows surveying tasks that traditionally required multiple people to be completed by one person, has attracted significant attention.

What is one-man surveying and why is it drawing attention?

One-man surveying, literally, is surveying performed by a single person (also called "single-person surveying"). Normally, surveying work is carried out by teams of two or more workers cooperating. For example, with total station surveying, the basic operation involved two people: one operating the instrument and the other holding a prism at a remote point. But the use of advanced technologies has opened up the possibility of completing surveying tasks that used to require multiple people both accurately and quickly by a single person. The Ministry of Land, Infrastructure, Transport and Tourism–led *i-Construction* (ICT use on construction sites) initiative has also been a tailwind, and one-man surveying is coming into the spotlight as a next-generation workflow that achieves labor savings and efficiency on site.

The main reason one-man surveying is attracting attention is that it can compensate for on-site labor shortages and improve productivity. If surveying that previously required multiple people can be done by one person, not only are labor costs reduced, but surveying can be conducted in parallel with other tasks, smoothing overall site progress. In cases where heavy machinery had to be stopped and kept idle while waiting for the surveying team to arrive, one-man surveying allows measurements to be taken immediately when needed, significantly reducing time loss caused by "waiting for surveying." Also, if surveying does not have to rely solely on specific skilled personnel, the risk of construction stalling when those personnel are absent is reduced. In other words, surveying that can be done by one person increases site flexibility and contributes to better risk management and productivity for the entire project.

How one-man surveying changes site operations

When surveying can be done by a single person, various changes appear in construction site operations. First, the freedom of personnel allocation increases dramatically. Limited staff can be allocated more efficiently, allowing workers to be reassigned to other tasks as needed. Traditionally, it was necessary to secure dedicated survey personnel or assistants for surveying tasks, but with the introduction of one-man surveying, the premise of "securing separate surveying personnel" is beginning to break down. This is a great advantage especially at earthworks or land development sites where topographic surveys and as-built checks are frequently performed, because a person who can move nimbly alone is very beneficial.

The spread of one-man surveying also directly reduces on-site waiting times. If you no longer need to temporarily suspend heavy machinery or other work for surveying, it contributes to shorter construction periods and cost reductions. If the system is arranged so that the necessary person can measure immediately when required, it becomes possible to respond flexibly to sudden weather changes or schedule adjustments. Because specific tasks do not depend on specific staff, the overall site can continue to progress even if a person is absent, which is also advantageous for risk management. With population decline and an aging society, one-man surveying is not merely a labor-saving measure but an important key to supporting the sustainability of site operations.

Technological advances that made one-man surveying possible

What made one-man surveying possible is the dramatic recent progress in surveying technology. Conventional optical surveying inevitably required two or more people, but new technologies are overturning that common sense. A representative example is the emergence of the auto-tracking total station. Because the instrument itself automatically tracks the prism, an operator can walk around holding the prism and observe survey points alone. Also, solutions such as photogrammetry with drones and 3D point cloud surveys using terrestrial laser scanners—where terrain data can be acquired without a person operating the machine—have become widespread. These technologies reduce the personnel required for surveying and contribute to significant efficiency gains.

That said, auto-tracking total stations are expensive and require operational proficiency, and drone surveys have constraints such as weather and no-fly zones. They are not universally applicable to all sites. Amid these limitations, particularly notable is RTK surveying using GNSS for one-man surveying. GNSS is a general term for satellite-based positioning systems, and the RTK (real-time kinematic) method uses correction information from reference stations to reduce satellite positioning errors to the centimeter level. With RTK surveying, a combination of a single receiver and a base station (or a correction information service) enables real-time centimeter-level high-precision positioning. It eliminates the need for complicated optical instrument setup and allows a single person to move nimbly even over wide sites.

With the advent of these new technologies, the fixed notion that "surveying requires large equipment and multiple-person teams" is beginning to break down. A symbol of this change is the arrival of the pocket-sized RTK-GNSS surveying device known as LRTK. In the next section, we will look in detail at how this LRTK makes one-man surveying possible and is reshaping conventional on-site practices.

What LRTK is: mechanism and basic performance

LRTK (el-ar-tee-kay) is a palm-sized, compact, lightweight RTK-GNSS receiver developed by a startup originating from Tokyo Institute of Technology. By attaching it to a smartphone such as an iPhone or iPad via a dedicated case, an everyday smartphone instantly becomes a centimeter-class precision surveying device. It weighs about 125 g and has a thickness of only about 1-2 cm (0.4-0.8 in), making it extremely compact and pocketable. There is no need to carry large tripods or heavy surveying equipment; it is a handy surveying terminal that you can quickly take out and walk around the site to take measurements as needed.

LRTK achieves high precision through the RTK technology mentioned above. A smartphone’s built-in GPS can have errors of several meters, but LRTK uses correction information via the internet to reduce that error to a few centimeters. It supports networked RTK services such as the Geographical Survey Institute’s continuous operating reference station network and private services (Ntrip method), receiving correction data from reference stations in real time to improve accuracy. After powering on and acquiring satellites, it typically obtains an RTK solution (Fix) in about 20-30 seconds, allowing surveying to start immediately. Furthermore, it supports Japan’s quasi-zenith satellite Michibiki’s centimeter-class positioning augmentation service (CLAS). Because it can receive augmentation signals directly from satellites even in mountainous areas where mobile signals do not reach, centimeter-level positioning is possible on-site even without network connectivity. It is revolutionary that precision surveying, which used to require specialized knowledge and expensive stationary equipment, can now be performed with a palm-sized device anyone can handle.

The existence of a dedicated smartphone app for positioning is also indispensable when discussing LRTK. Once you start the app and connect the receiver, satellite acquisition and correction information reception settings are handled automatically, and the user can intuitively record survey points. For example, at the point you want to measure, you can tap a button on the phone screen to instantly acquire and save position information including latitude, longitude, and elevation. Point names, timestamps, and GNSS reception status are recorded simultaneously, eliminating the need to take handwritten notes in a field notebook. Recorded coordinate data are automatically converted to Japan’s plane rectangular coordinate system or the World Geodetic System (WGS84), and geoid height calculations are performed automatically as well, so even those without expert knowledge can obtain accurate surveying results. The device is designed for ease of use so that anyone can operate it with simple button operations without worrying about complex settings or calculations.

In this way, LRTK, combined with a smartphone, becomes a versatile surveying terminal that enables anyone to perform precision surveying easily. Its convenience and practicality are quietly creating a trend on sites as a tool that allows measurements "anytime, anywhere." Developers say they aimed for "a one-per-person field tool that can be kept in a pocket at all times and used whenever needed," and LRTK is exactly the ideal device that allows advanced surveying tasks to be performed as an extension of daily work without special qualifications or experience.

Accuracy and reliability achievable with LRTK

Using LRTK, anyone on site can achieve high-precision positioning within an error range of several centimeters. The RTK method’s "Fix solution" is extremely precise, with errors around ±2-3 cm (±0.8-1.2 in), far surpassing standalone positioning. With this level of accuracy, it is sufficient for the surveying precision required for creating topographic maps and construction management. In practice, coordinate data obtained with LRTK can be used directly for as-built control, earthwork volume calculations, and plotting on drawings without additional corrections or manual adjustments.

Moreover, because LRTK combines signals from multiple satellites with base station correction information, it provides stable accuracy and thus reliability. Its compatibility with the CLAS signal from Michibiki, Japan’s quasi-GPS, is a major strength, enabling it to maintain centimeter-level accuracy even at sites in mountainous areas that are normally difficult to position. Even if internet connectivity is lost during measurement, CLAS can autonomously maintain accuracy, allowing stable surveying that is less affected by site conditions.

From a data reliability perspective, LRTK also offers strong advantages. Survey point information is automatically recorded and saved by the smartphone app, eliminating transcription or input errors caused by manual writing. Acquired data are backed up to the cloud, so even if the on-site device fails or is lost, the information is not lost. Cloud-based coordinate data can be immediately checked and verified from office PCs, making it easy for supervisors and colleagues to confirm the on-site measured values. LRTK is a highly reliable solution that can be used with confidence on site due to its high positioning accuracy and robust data management.

Effects on work efficiency and labor savings

One of the effects expected from introducing LRTK is a dramatic improvement in surveying work efficiency. Traditionally, tasks from survey planning to equipment preparation, observation of survey points, teardown, data organization, and drafting required a lot of time and effort. With smartphone surveying using LRTK, you can take out the device and start observations immediately when you want to measure, obtaining results with minimal steps. For example, even when measuring numerous points across a large site, one person can complete measurements quickly without carrying heavy equipment for setup and relocation. In rough terrain or on difficult walking surfaces, the pocketable LRTK reduces the burden of movement, allowing safe measurement of necessary locations. As a result, daily work volume can increase while reducing physical strain on workers.

Regarding operational efficiency, the ease of operation and automation of data processing are also notable. The LRTK app features a simple UI that anyone can use without specialized knowledge, and point recording is completed with the push of a button. Users do not need to consider coordinate calculations or correction procedures each time they measure, so anyone on site can use it without confusion. This shortens the training period required for surveying and allows immediate deployment as practical personnel from the day they start fieldwork. Also, measured data are automatically saved and synchronized to the cloud on-site, significantly reducing later office tasks such as manual data entry or drawing creation. Because site-acquired information can be shared immediately with everyone, there is no waiting time for survey results. Real-time information linkage between the field and the office enables faster decision-making and schedule management.

From the perspective of labor savings, LRTK has a large impact. The device itself is very low cost compared to traditional surveying instruments, removing the constraint of "only a limited number of expensive machines can be provided." In extreme cases, it is conceivable that every on-site worker could carry their own LRTK. If everyone from newcomers to veterans has a precision surveying tool at hand and can measure immediately when needed, the reliance on a single surveyor can be eliminated. Multiple people can measure different locations simultaneously without issue, and by eliminating "waiting for surveying" and advancing tasks in parallel, overall site productivity can skyrocket. Allowing non-survey specialists to measure and record on site removes the dependence on specific individuals, enabling more standardized and efficient workflows.

Concrete examples on operating sites

Now let’s look at concrete examples of how one-man surveying can affect actual sites. LRTK’s strength is particularly evident in civil engineering works such as earthworks. Earthworks refer to tasks for shaping the ground, such as excavation, embankment, and leveling. On earthwork sites, surveying is frequently required for confirming ground elevations before and after start, measuring excavation and fill volumes, and checking as-built shapes after construction. In the past, surveyors would be called to site each time, or heavy equipment operators would have to halt work while waiting for a surveying team to arrive. But with LRTK, site workers can measure needed data themselves on the spot, enabling instant assessment without interrupting workflow.

For example, a heavy equipment operator or site supervisor can take an LRTK device from their pocket, quickly measure several surrounding ground elevations, and immediately calculate fill or excavation volumes based on that information. Because a nearby specialist surveyor is not required and one person can respond, personnel allocation becomes more efficient and construction costs are reduced. Also, measurement data shared in real time via the cloud can be instantly checked from headquarters or the office. This allows headquarters staff to immediately grasp the latest site conditions and give instructions, facilitating a speedy PDCA cycle for earthwork management and schedule control.

Furthermore, because LRTK is compact and lightweight, it can be easily carried and used in steep development sites or locations with poor footing. There is no need to carry heavy tripods or instruments up and down slopes, enabling one person to safely measure required points. This not only reduces physical burden on workers but also decreases risks such as falls, contributing to improved site safety.

Because earthwork sites demand speed and flexibility, they stand to gain the most from one-man surveying. With LRTK, short moments before morning meetings can be used to measure progress up to the previous day and share it with stakeholders, or discrepancies between design drawings and current conditions can be checked on the spot and immediate countermeasures taken. Having a system where you can "measure immediately when you want to measure" allows site operations to become faster and less wasteful than before.

Workflow for one-man surveying with LRTK

Let’s look at the typical procedure when conducting one-man surveying with LRTK. Here we assume a case where a single person performs everything from reference point surveying to stake setting, and introduce the sequence of operations.

• Attach device and start positioning: Upon arrival at the site, first attach the LRTK receiver to your smartphone (e.g., iPhone) and power it on. Start the dedicated app and set how to receive satellite correction information (network RTK via mobile networks or Michibiki CLAS reception). Within about 20-30 seconds the RTK status will typically become FIX (error around ±2-3 cm (±0.8-1.2 in)), and high-precision positioning will be ready.

• Measure reference points: Next, at known reference points or chosen control points, hold the LRTK and tap the app’s measurement button to record coordinates. Latitude, longitude, and elevation data are saved instantly, and you can enter point names or notes as needed. Recorded point information is automatically synchronized to the cloud, so if you have network connectivity on site, it can be checked in real time from the office PC (if recorded offline, you can upload it manually later).

• As-built surveying (including point cloud acquisition): Then proceed alone to measure necessary locations around the site in sequence. At each point to be measured, simply hold up your smartphone and press the button to acquire coordinates one after another. If vertical measurements are needed, attach the LRTK to an included pole (monopod), place the pole tip on the ground, and measure to obtain accurate ground elevations. At key locations, you can also use the iPhone or iPad’s built-in LiDAR sensor to scan the surroundings and capture terrain and structures as point cloud data. This point cloud data will be useful later for creating 3D models or checking cross-sections.

• Import design data: Next, call up pre-uploaded design coordinates and drawing data from the cloud within the app, and select target points for staking or checking. For example, if a list of design coordinates for stakes to be installed on site is prepared, select a coordinate from that list. Because design data are synchronized via the cloud, this action alone sets the target point information on the smartphone.

• Navigation and AR-based stake setting: When you press the app’s navigation start button, the phone screen displays the direction and distance to the target point. Follow the arrow guidance and, when you reach the target vicinity, switch the display to AR mode. A virtual stake (AR marker) appears in the camera view at the specified coordinate position, so adjust your position until the virtual stake appears to be firmly placed in the actual ground. That is the point to set the stake. Mark the ground there and install the stake. This completes accurate positioning (layout) without needing another person’s assistance.

• As-built confirmation and recording: After placing the stakes, check and record the surrounding as-built conditions as required. For instance, to verify that stake head elevations and nearby pavement elevations conform to design, measure the stake top or pavement elevation with LRTK. Measured point data are displayed instantly on the smartphone screen, and differences from preloaded design elevations are calculated automatically. You can determine on the spot whether the values fall within allowable tolerances; if so, the inspection is complete. Finally, take a few site photos for records (photos are geotagged, so you can immediately identify where each photo was taken later).

Being able to perform all these steps alone with a single smartphone is the greatest strength of one-man surveying with LRTK. Tasks that previously required multiple people and days—such as reference point surveys and stake setting—can be completed with a few simple steps. This enables construction managers to conduct necessary surveying and inspections at the right time, dramatically improving site productivity and agility.

Conclusion: The new era of one-man surveying and why you should adopt LRTK

Amid severe labor shortages and ongoing workstyle reforms, the realization of one-man surveying is becoming a major boon for the construction and surveying industries. The new surveying workflow enabled by LRTK allows high-precision surveying with small teams, and its real-time information sharing and standardization of operations are transforming site management. It eliminates inefficiencies such as "waiting for surveying" and rework caused by human error, enabling both quality assurance and DX (digital transformation) promotion. As complex surveying tasks are replaced by intuitive smartphone operations, conventional site practices are undergoing major change.

Take this opportunity to introduce one-man surveying with LRTK on your site. Embrace the latest technology, update traditional workflows, and evolve your site to the next stage.