LRTK in the Spotlight in the Surveying Industry | Making One-Person Surveying Easier

How much could work efficiency improve if a single person could survey a site alone? For many years in construction and civil engineering, the norm has been 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-person surveying that can be completed by a single person has been attracting attention. Amid severe labor shortages and the push for work-style reform, it is being seen as a trump card for running sites efficiently with limited personnel.

In reality, the aging of civil engineers and the decline in young entrants has made securing personnel capable of surveying a major challenge on job sites. As veteran surveyors retire, there are insufficient successors, and it’s not uncommon for staff to be assigned to multiple sites. In addition, the working-hours regulations under the 2024 work-style reform-related laws (the so-called "2024 problem") are fast approaching, increasing the need to complete surveying tasks efficiently within limited time and manpower. Against this backdrop, one-person surveying, which allows tasks that used to require multiple people to be completed by a single person, is drawing significant attention.

What is one-person surveying and why is it attracting attention?

One-person surveying, as the name implies, is surveying carried out by a single person (also called "solo surveying"). Typically, surveying tasks are performed by teams of two or more people cooperating. For example, with total station surveying, the basic operation used to be a two-person team where one person operates the instrument and the other holds a prism at a distant point. However, thanks to advanced technologies, tasks that previously required multiple people can now potentially be completed by one person accurately and quickly. The Ministry of Land, Infrastructure, Transport and Tourism–led *i-Construction* initiative (promoting ICT use on construction sites) has also provided a tailwind, and one-person surveying is being highlighted as a next-generation workflow to reduce manpower and increase efficiency on sites.

The main reason one-person surveying is attracting attention is that it helps cover labor shortages and improve productivity. If surveying that once required multiple people can be done by one, not only can labor costs be reduced, but surveying can be carried out in parallel with other tasks, smoothing overall site progress. In cases where heavy machinery had to be stopped while waiting for the surveying crew to arrive, one-person surveying allows immediate measurement when needed, dramatically reducing time loss due to "waiting for surveying". Also, if surveying work does not rely solely on a specific skilled person, the risk of work being delayed when that person is absent is reduced. In short, surveying that one person can perform increases site flexibility and contributes to overall risk management and productivity improvements.

How one-person surveying changes site operations

When surveying can be done by one person, various changes occur in construction site operations. First, the flexibility of personnel allocation increases significantly. Limited staff can be deployed more efficiently, allowing people to be reassigned to other tasks as needed. Traditionally, it was necessary to secure dedicated survey personnel or assistants for surveying tasks, but the introduction of one-person surveying is beginning to break down the premise of "securing separate surveying staff." In sites such as earthwork or land development, where terrain surveys and as-built checks are frequently required, the ability for one person to move nimbly is a major advantage.

Furthermore, the spread of one-person surveying directly reduces on-site waiting times. If it’s unnecessary to pause heavy equipment or other work for surveying, it contributes to shorter construction periods and cost savings. Having a system where the person who needs to measure can do so immediately makes it possible to respond flexibly to sudden weather changes or schedule adjustments. Because specific tasks are not dependent on specific staff, the site can continue progressing even if someone is absent, which is also advantageous for risk management. As Japan’s population ages and birthrates decline, one-person surveying will be more than just a manpower-saving measure; it will become an important key to sustainable site operations.

Technological advances that made one-person surveying possible

One-person surveying has been enabled by recent leaps in surveying technology. Traditional optical surveying inevitably required two or more people, but new technologies are overturning that assumption. A representative example is the emergence of automatically tracking total stations. Since the instrument itself can automatically track the prism, an operator can walk around holding the prism and observe survey points by themselves. Additionally, solutions such as drone photogrammetry and ground-based laser scanners for 3D point cloud surveying, which can acquire terrain data without manual operation, are also becoming widespread. These technologies reduce the personnel required for surveying and contribute greatly to efficiency.

That said, automatically tracking total stations are expensive and require operational skill, and drone surveys face constraints such as weather and no-fly zones. They are not universally applicable to all sites. In this context, RTK surveying using GNSS has drawn particular attention for enabling one-person surveying. GNSS is the general term for satellite-based positioning systems, and the RTK (real-time kinematic) method uses correction information from a base station to reduce satellite positioning errors to the order of centimeters. With RTK surveying, a single receiver combined with a base station (or correction information service) can provide real-time centimeter-level high-accuracy positioning. Because it does not require setting up complex optical equipment, and because a single operator can survey large sites with high mobility, this advantage is significant.

With these new technologies, the fixed belief that "surveying must be performed with large equipment and a multi-person team" is beginning to crumble. Symbolizing this shift is the emergence of the pocket-sized RTK-GNSS surveying device known as LRTK. The next section examines in detail how LRTK enables one-person surveying and is poised to rewrite site conventions.

What LRTK is: mechanism and basic performance

LRTK (pronounced “ell-ahr-tee-kay”) is a palm-sized, lightweight RTK-GNSS receiver developed by a startup from the Tokyo Institute of Technology. When attached to a smartphone such as an iPhone or iPad via a dedicated case, an everyday smartphone instantly becomes a centimeter-level precision surveying instrument. Weighing about 125 g and with a thickness of about 1–2 cm, it is extremely compact and pocketable. There is no need to carry large tripods or heavy surveying equipment, and it becomes an easy-to-use surveying terminal that can be quickly taken out and used to walk around the site to take measurements.

LRTK achieves high accuracy through the RTK technology mentioned earlier. Standalone smartphone GPS can have errors of several meters, but LRTK corrects those errors to the centimeter level by using satellite positioning together with correction information delivered over the internet. It supports network RTK (Ntrip method) such as the Geospatial Information Authority of Japan’s Continuously Operating Reference Stations and commercial services, improving accuracy by receiving real-time correction data from base stations. After powering on and acquiring satellites, it typically takes about 20–30 seconds to obtain an RTK solution (Fix), allowing surveying to start immediately. In addition, it supports the centimeter-level augmentation service (CLAS) provided by Japan’s quasi-zenith satellite Michibiki. Because it can receive augmentation signals directly from satellites, it can achieve centimeter-level positioning even in mountainous areas without mobile network coverage. Making precision surveying—which previously required specialized knowledge and expensive, fixed equipment—available to anyone in a palm-sized device is truly revolutionary.

The dedicated smartphone app used for positioning is also indispensable when discussing LRTK. When the app is launched and the receiver is connected, satellite acquisition and correction information reception settings are automatically configured, and users can intuitively record survey points. For example, tapping a button on the phone screen at the point you want to measure instantly captures and saves location data including latitude, longitude, and height. Point names, timestamps, and GNSS reception status are also recorded simultaneously, eliminating the need to write notes in a paper field notebook. The 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, so accurate surveying results can be obtained even without specialist knowledge. The device is designed for ease: anyone can operate it with button presses without needing to be aware of 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 ease of use and practicality are quietly creating a trend on sites as a tool that lets users "measure anytime, anywhere." The developers have stated they aimed to create a site tool that "fits in a pocket, is carried at all times, and is available to use whenever needed"—an ideal device that allows advanced surveying tasks to be carried out in the course of everyday work without special qualifications or experience.

Accuracy and reliability achieved with LRTK

Using LRTK enables anyone on-site to achieve high-accuracy positioning within a few centimeters. The RTK "Fix" solution provides very precise accuracy on the order of ±2–3 cm, which is far beyond standalone positioning. With such accuracy, it is sufficient for producing topographic maps and for the surveying accuracy required in construction control. In practice, coordinate data obtained with LRTK can be used directly for as-built management, earthwork volume calculations, and plotting on drawings without additional corrections or rework.

Moreover, LRTK offers reliability because it combines signals from multiple satellites with base station correction information to provide stable accuracy. Its support for the CLAS signal from Michibiki, Japan’s quasi-zenith satellite system, is a major strength because it allows centimeter-level accuracy to be maintained even at sites—such as in mountainous regions—where positioning is usually difficult. Even if internet connectivity is lost during measurements, CLAS can autonomously maintain accuracy, enabling stable surveying that is less affected by site conditions.

From a data reliability perspective, LRTK also has notable strengths. Survey point information is automatically recorded and saved by the smartphone app, eliminating transcription or input errors caused by manual recording. The acquired data are backed up to the cloud, so if the on-site device fails or is lost, information is not lost. Cloud-stored coordinate data can be checked and verified immediately from office PCs, making it easy for supervisors and colleagues to cross-check that the measured values are correct. LRTK’s high positioning accuracy and robust data management make it a reliable solution that can be trusted on site.

Effects on work efficiency and manpower reduction

One of the anticipated benefits of introducing LRTK is a significant increase in surveying efficiency. Traditionally, surveying involved considerable time and effort from planning and equipment preparation to point observation, teardown, data organization, and drawing production. With smartphone surveying using LRTK, you can take out the device and start observations immediately when you need to measure, obtaining results with the minimum necessary steps. For example, even when measuring many points across a large site, a single person can finish quickly because there is no need to carry and set up heavy equipment. In rugged terrain or on poor footing, a pocketable LRTK reduces the burden of moving around, allowing safe measurement of required locations. As a result, daily work capacity can increase while reducing the physical burden on workers.

In terms of operational efficiency, the ease of operation and automated data processing are also key. The LRTK app has a simple UI that anyone can use without specialist knowledge, and point recording is completed with a single button. There’s no need to focus on coordinate calculations or correction processing each time you measure, and the device is designed so anyone on site can use it without hesitation. This shortens the training period required for surveying tasks and allows personnel to be productive from their first day on site. Additionally, measured data are automatically saved and synchronized to the cloud, greatly reducing the need to manually input data into office PCs or convert to drawings after returning to the office. Because local measurements can be shared immediately with everyone, there is no waiting for survey results. Real-time information linkage between the site and office enables faster decision-making and schedule management.

From the perspective of manpower reduction, LRTK also brings great benefits. The device itself is far less expensive than traditional surveying equipment, removing the constraint that only a limited number of costly machines can be provided. In the extreme, each site worker could carry their own LRTK. If everyone from newcomers to veterans has a precise surveying tool at hand and can measure immediately when needed, dependency on a single surveyor can be eliminated. Multiple people can measure different locations simultaneously without issues, so resolving "waiting for surveying" and advancing parallel tasks can dramatically raise overall site productivity. As non-survey specialists become able to measure and record on site, task specialization is reduced, and more standardized and efficient workflows can be implemented.

Concrete examples on operating sites

Now let’s look at specific examples of how one-person surveying benefits actual sites. LRTK’s strengths are especially evident in civil earthwork sites. Earthwork refers to excavation, embankment, and leveling work involved in ground formation. On earthwork sites, surveying is frequently required for checking ground elevation before and after construction, measuring excavation and embankment volumes, and confirming as-built condition (completed terrain). Traditionally, surveyors would be called in for these tasks, or heavy machinery operators would have to pause while waiting for the surveying crew. However, with LRTK, site workers themselves can measure the data needed on the spot, enabling immediate understanding of conditions without halting work.

For example, a heavy equipment operator or site supervisor could take an LRTK device from their pocket, quickly measure several surrounding ground elevations, and instantly calculate embankment or excavation volumes based on that information. Since it only takes one person to respond, this contributes to more efficient personnel allocation and reduced construction costs. Also, measurement data shared in real time via the cloud can be checked immediately by remote head office or office staff. This allows head office personnel to grasp the latest on-site status and issue instructions quickly, speeding up the PDCA cycle for earthwork quantity control and schedule management.

Furthermore, because LRTK is small and lightweight, it is easy to carry and measure even on steeply sloped or difficult-to-access development sites. There is no need to lug heavy tripods and equipment up and down slopes, and a single person can safely conduct measurements where needed. This not only reduces the physical burden on workers but also lowers the risk of falls and other accidents, contributing to improved site safety.

The benefits of one-person surveying are greatest on earthwork sites that require speed and flexibility. With LRTK, for example, it becomes feasible to measure progress in the short time before morning meetings and share it with stakeholders, or to immediately check differences between design drawings and actual conditions and take corrective actions on the spot. By establishing a system in which you can "measure whenever you need to," site operations can become faster and more efficient than ever.

Workflow for one-person surveying with LRTK

Here is what the procedure looks like when performing one-person surveying with LRTK. Below we assume a case in which a single person performs control point surveying and stakeout for layout, and we outline the sequence of operations.

• Attach device and start positioning: Upon arriving at the site, first attach the LRTK receiver to your smartphone (e.g., iPhone) and power it on. Launch the dedicated app and set how you will receive satellite correction information (network RTK via mobile network or Michibiki CLAS reception). In about 20–30 seconds the RTK status will reach FIX (approx. ±2 cm), and high-accuracy positioning will be ready.

• Measure control points: Next, at known points or selected reference points, hold the LRTK and tap the app’s measurement button to record coordinates. Latitude, longitude, and height data are saved instantly, and you can optionally enter point names or notes. Recorded point information is automatically synchronized to the cloud, so if there is network coverage you can verify it from an office PC in real time (if recorded offline in a no-coverage area, you can upload later manually).

• As-built surveying (including point cloud acquisition): Then, walk around the necessary locations on the site and take measurements one by one. At each point, simply hold up the phone and press the button to capture coordinates. For vertical measurements, attach the LRTK to an included pole (monopod), place the pole tip on the ground, and measure to obtain accurate ground elevation. At key locations, you can also use the LiDAR sensor built into an iPhone or iPad to scan the surroundings and acquire point cloud data of terrain or structures. This point cloud data is 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 into the app and select target points for stakeout or verification. For example, if a list of design coordinates for stakes to be installed is available, select a coordinate from the list. Because the design data are synced via the cloud, this operation alone sets the target point information on the smartphone.

• Navigation and AR-assisted stakeout: Press the app’s navigation start button to display the direction and distance to the target point on the phone screen. Follow the arrow guidance and, when near the destination, switch the screen to AR mode. A virtual stake (AR marker) appears in the camera view at the specified coordinate, allowing you to fine-tune your position and find where the virtual stake appears to be firmly planted in the actual ground. That location is where you should set the stake. Mark the spot and install the stake—completing accurate stakeout (layout) without assistance from others.

• As-built confirmation and recording: After installing stakes, confirm and record the surrounding as-built condition as needed. For example, measure the stake top elevation or surrounding pavement elevation with LRTK to check whether they match the specified values. Measured points are displayed immediately on the phone, and height differences from pre-imported design elevations are calculated automatically. You can judge on the spot whether they are within tolerances and, if acceptable, complete the verification. Taking a few site photos as a final record is also recommended (photos are geotagged, so you can tell at a glance where each photo was taken later).

Being able to perform all of these steps alone with just a smartphone is the greatest strength of one-person surveying using LRTK. Tasks such as control point surveying and stakeout that once took multiple people several days can now be finished with a few simple steps. This enables construction managers to perform surveying and verification at the moment they are needed, dramatically improving site productivity and responsiveness.

Conclusion: A new era of one-person surveying and recommended use of LRTK

Amid severe labor shortages and ongoing work-style reforms, the realization of one-person surveying is becoming a major boon for the construction and surveying industries. The new surveying workflow enabled by LRTK allows high-accuracy surveying with minimal personnel and, through real-time information sharing and workflow standardization, is transforming site management. It eliminates inefficiencies such as "waiting for surveying" and rework caused by human error, and serves as a solution that can simultaneously ensure quality and promote DX (digital transformation). With advanced skills and experience being replaced by intuitive smartphone operation, the very conventions of site work are beginning to change.

Now is a great opportunity to introduce one-person surveying using LRTK at your sites. Embrace the latest technology to update traditional workflows and take your site to the next stage.