The deciding factors for solo surveying are communication and accuracy: Why LRTK’s RTK/GNSS is chosen

Solo surveying, which enables field surveying tasks to be completed by a single person, is attracting attention. Tasks that were traditionally performed by a team of a surveyor and assistants—such as staking out positions and checking as-built conditions—are becoming feasible for a lone operator thanks to advances in GNSS technology and data communication infrastructure. However, to make solo surveying successful, two key elements are essential: “communication” and “accuracy.” This article explains why communication environment and positioning accuracy are decisive for solo surveying, and introduces the reasons why LRTK’s RTK/GNSS solution is being chosen on sites as a way to achieve both.

Challenges at surveying sites and the need for solo surveying

Conventional surveying work has long relied on specialized skills and multiple personnel. Using tools such as tape measures, staffs (level rods), levels, and transits, the traditional relative-measurement methods from reference points typically required teams of 2–3 people. For example, one person would operate the instrument on a tripod while another held a staff at a distant point to establish positions. Such manual-intensive surveying involved significant setup and teardown time, and when there were many measurement points or a large site, it was not uncommon for surveying alone to take an entire day.

Manual measurement also carries the risk of human error. Misreading numbers or recording mistakes can cause rework in later stages, potentially delaying schedules and increasing costs. Limited time and personnel make it difficult to measure every point, so typically only seemingly important locations were measured. As a result, issues at unmeasured locations could go unnoticed.

Amid this, the construction industry is facing increasingly severe labor shortages and aging of the workforce. With fewer experienced surveyors, continuing to rely on people for surveying is becoming difficult, and new methods that enable high-precision surveying with fewer personnel are needed. GNSS (Global Navigation Satellite System)-based solo surveying is being anticipated as a game changer. Solo surveying can greatly reduce on-site work effort while potentially ensuring the required accuracy. The next section looks at the evolution of GNSS and RTK technology, which hold the key.

How GNSS and RTK technology enable solo surveying

GNSS (satellite navigation), which uses satellites to determine position, is familiar from car navigation and smartphone map apps. Numerous satellites operate worldwide, including GPS (United States), GLONASS (Russia), Galileo (Europe), and QZSS “Michibiki” (Japan), making it easy to obtain latitude, longitude, and altitude anywhere on Earth. GNSS holds great promise for surveying. Unlike traditional relative optical surveying (measuring from reference points with transits or total stations), GNSS surveying can directly determine an absolute position with satellites as the reference, making it powerful for understanding position relationships between widely separated points and for large-area terrain surveys. Even in areas with poor line-of-sight like mountainous regions, GNSS can be used if the sky is open, expanding applicability to sites that were previously difficult to survey.

However, standalone positioning using a typical GNSS receiver yields accuracy on the order of several meters. That is insufficient for construction surveying or boundary checks, which require centimeter-level accuracy (cm level accuracy (half-inch accuracy)). For example, GPS in smartphones can have errors of about 5–10 m, which is inadequate for staking out or as-built verification that require precision. This led to the adoption of RTK (Real Time Kinematic), which corrects GNSS positioning errors.

RTK works by having a known, accurately referenced base station and a rover receive satellite signals simultaneously. The base station computes error information and transmits it to the rover via communication, and the rover applies those corrections to its own position. Because errors can be canceled in real time, standalone errors of several meters can be reduced to several centimeters. Previously, high-precision positioning at reference points required long static observations, but with practical RTK, cm-level positioning became possible immediately, and RTK has spread in civil engineering and construction since the 1990s.

To perform RTK surveying conventionally, a dedicated base station near the work site (within a few km) had to be installed. That preparation and operation required specialized knowledge, and the equipment was often large and expensive, creating a barrier for small contractors and municipalities. Also, the traditional style—experienced operators carrying heavy gear to the site and operating base and rover as a team—meant that the high precision achieved with RTK did not necessarily lead to labor savings. In response, easier, lower-personnel RTK solutions were demanded. This led to the development of network RTK services that utilize networks like the Geospatial Information Authority of Japan’s Continuously Operating Reference Stations. Approaches such as VRS (Virtual Reference Station) create a virtual base station near the user and deliver correction information, so that receiving correction data over the internet alone enables a single rover to achieve cm level accuracy (cm level accuracy (half-inch accuracy)). Today, many high-precision GNSS correction services are offered commercially and publicly, so high-precision positioning is increasingly possible without maintaining your own base station.

Thus, the evolution of GNSS and RTK technologies has laid the foundation for solo surveying. The next section digs deeper into “communication,” one of the critical factors determining the success of solo surveying.

Communication infrastructure that supports solo surveying

In RTK, which provides high-precision positioning in real time, communication to transfer correction data from the base station to the rover is indispensable. In other words, without a stable communication environment, solo surveying cannot maintain its accuracy. Traditionally, this involved setting up radio modems between the base and rover or connecting to correction services over the internet. These setups and preparing communication devices required expertise and labor, such as installing repeaters and checking radio conditions.

Today, the barrier has been greatly lowered by using smartphones and mobile communications. By connecting a smartphone to the internet on site and accessing Ntrip-compatible correction services (network RTK services), correction data can be received in real time without dedicated radio equipment. For example, accessing correction information from the Geospatial Information Authority of Japan’s roughly 1,300 continuously operating reference stations via a smartphone provides the same effect as having a nearby virtual reference station. As long as mobile coverage is available, a single rover can cover a large work area.

Moreover, even in mountainous areas without cellular service or in the immediate aftermath of disasters, solo surveying need not be abandoned. Japan’s QZSS “Michibiki” provides a free high-precision augmentation service (CLAS) that allows direct reception of correction signals from satellites without an internet connection. LRTK devices support CLAS signals as well, so in open-sky locations RTK positioning can continue even outside cellular coverage. This enables rapid site recording via solo surveying in locations previously difficult to survey due to lack of communication infrastructure or during emergencies.

Communication is also crucial for sharing survey data. Traditionally, survey results were recorded on paper or USB and brought back to the office for PC upload and sharing, which introduced delays between finding an issue on site and notifying stakeholders. Systems like LRTK that integrate smartphones with the cloud allow measurement data to be uploaded on the spot and shared with office staff in real time. Measured coordinates can be immediately checked against design drawings or GIS maps, and results can be reported to supervisors, helping prevent rework and speeding decision-making. In short, “communication” in solo surveying encompasses both the transmission of correction information and the sharing of data, and these communications are lifelines for efficiency and accuracy.

The high accuracy required for solo surveying

Another critical point in discussing solo surveying is positioning accuracy. Surveying aims to obtain accurate position data of terrain and structures and to place stakes or markers according to design. Position data with errors of several meters is unusable. Especially for as-built management on construction sites and boundary verification, even a few centimeters of error can be unacceptable, so high-precision surveying is essential. Traditionally, surveyors used optical instruments such as levels and total stations, and experienced technicians invested time to ensure accuracy. Solo surveying must achieve equivalent accuracy to be trusted.

Fortunately, as described above, RTK enables GNSS to achieve centimeter-level positioning (cm level accuracy (half-inch accuracy)). Using network RTK services, high accuracy can be maintained uniformly regardless of location on site. There is no need to worry about accuracy degrading with distance from a base station, and stable positioning can be maintained while moving over wide areas. This stable high accuracy is the foundation that makes solo surveying feasible.

For example, using an LRTK device can yield horizontal accuracy on the order of ±1–2 cm (±0.4–0.8 in) and vertical accuracy of ±3–4 cm (±1.2–1.6 in). This level of accuracy is incomparable to typical smartphone GPS errors of 5–10 m and rivals conventional optical surveying instruments. In sites where LRTK has been adopted, tasks that previously required two people and a full day for as-built measurements have been completed by one person in just a few hours. Rapid acquisition of precise data makes it possible to measure all necessary points and prevent unforeseen problems from unmeasured locations.

Obtaining high-precision data quickly also benefits safety and quality control. Improved surveying efficiency reduces workers’ exposure to heat and lowers heatstroke risk, and shortens time spent in hazardous areas. Digitally accurate data can be used directly in reports and drawings without risk of transcription errors. Systems that are easy for less experienced technicians to use reduce mistakes and make quality assurance of surveying easier. Thus, RTK/GNSS technology that delivers high accuracy is a crucial element supporting the reliability of solo surveying.

Why LRTK’s RTK/GNSS is chosen for solo surveying

As described above, establishing solo surveying requires meeting both communication environment and high accuracy simultaneously. A solution developed to achieve this easily is the ultra-compact GNSS receiver that pairs with smartphones: LRTK. LRTK is an innovative RTK-capable GNSS device that mounts on an iPhone. It weighs approximately 165 g and has a thickness of approximately 1 cm (0.4 in), smartphone-sized yet contains a high-precision positioning antenna and battery. By mounting it on the back of an iPhone and connecting via Bluetooth or Lightning, your handheld smartphone instantly becomes a high-precision GNSS surveying instrument. Where surveying equipment once weighed several kilograms and was stationary, miniaturization to a pocketable size means you no longer need to carry a tripod and heavy gear; a single smartphone now enables one person to complete surveying and staking tasks. It’s gaining attention as a solution that opens the era of “smartphone surveying.”

LRTK supports high-performance RTK and can utilize various correction sources in Japan, such as Ntrip corrections from the Geospatial Information Authority’s reference station network and CLAS signals from the QZSS Michibiki. In areas with mobile connectivity, VRS-based correction data can be obtained instantly for real-time correction. In regions outside cellular coverage, CLAS augmentation signals from satellites can be received directly to maintain cm level accuracy (cm level accuracy (half-inch accuracy)). In other words, stable high-precision surveying by a single person is achievable nationwide, from cities to remote mountains.

Ease of operation is another reason LRTK is chosen. On arrival at the site, simply attach the device to an iPhone, power it on, and launch the app; initialization completes in a few dozen seconds and positioning reaches FIX (fixed solution) status. Once FIX is achieved, high accuracy is maintained while moving, and if reception is briefly interrupted in a tunnel, centimeter precision is restored within seconds. There is no need to set up base stations repeatedly when moving around a large site; a single operator can continue surveying sequentially. This leads to significant savings in personnel and time.

Data management also benefits. LRTK supports cloud integration, allowing measurement data to be shared to the cloud from the field with a single tap. This eliminates the need to record numbers on paper and re-enter them later. By the time you return to the office, stakeholders can already have access to the results, so if missing measurements or errors are found, reporting and instructions can be issued immediately. Photo-attached records and automatic report generation functions streamline post-survey documentation. With all data stored in the cloud, it is easy to reference past survey results or centrally manage information from multiple sites, enabling DX (digital transformation) utilization.

Furthermore, intuitive smartphone operation is easy for both veterans and newcomers. Even those unfamiliar with dedicated surveying equipment can perform position measurements and inspections using an easy-to-understand app interface, raising the overall skill level of field technicians. It aligns with construction DX initiatives such as the Ministry of Land, Infrastructure, Transport and Tourism’s i-Construction, and LRTK can help facilitate smooth transition to digital technologies. In terms of cost, using an existing smartphone is far less expensive than acquiring large surveying instruments. Municipalities that adopted LRTK were able to procure devices economically and conduct rapid in-house surveying of disaster sites, reducing lead times and costs for recovery. These comprehensive benefits have led many sites seeking solo surveying to choose LRTK’s RTK/GNSS system.

Easy solo surveying with LRTK

Finally, imagine a typical workflow showing how simply solo surveying can be performed with LRTK.

• Preparation: Upon arrival, firmly attach the LRTK device to your iPhone and power it on. Launch the dedicated LRTK app (iOS supported), connect to the device, and start receiving GNSS satellites. After acquiring satellites, cm level accuracy (cm level accuracy (half-inch accuracy)) RTK positioning becomes available in about several tens of seconds; once the solution is FIX, you are ready to begin. No assistant is required—one person can start surveying.

• Measurement: Move to the point you want to measure and tap the button in the app to record that point’s high-precision coordinates. For large sites, simply walk around and capture points. The LRTK and smartphone combination can also automatically capture many points to generate 3D point cloud data, allowing one person to perform detailed terrain surveys that previously required specialized equipment.

• Staking out (positioning): Staking out positions specified in design drawings can be done accurately by one person. By entering the target coordinate in the LRTK app’s coordinate guidance feature, the screen displays the direction and distance to the target in real time. Following guidance like “5 cm east more” or “10 cm north” lets you fine-tune the position and complete staking that used to require two people.

• Verification and sharing: Measurement results can be viewed on the smartphone screen as numbers or graphs, and differences in elevation or distances can be checked in real time. Data can be uploaded to the cloud with one tap, so by the time you return to the office the team will already have access to the results. You can receive additional measurement instructions or immediately check consistency with drawings as needed, enabling a streamlined surveying workflow without waste.

By leveraging LRTK in this way, field surveying that once required multiple people becomes surprisingly simple. Solo surveying using GNSS and smartphones dramatically improves efficiency, and immediate data sharing enhances construction management accuracy. LRTK, which balances communication and accuracy, is becoming the new norm in the GNSS era. In an age of labor shortages, consider introducing smart solo surveying with LRTK at your sites.