Site DX Starts with Surveying! How i-Construction Is Changing the Norms of Solo Surveying

As digital transformation (DX) of construction sites rapidly advances, attention is focusing on the idea that site DX should begin with "surveying." Accurate site data obtained through surveying can be used consistently through subsequent construction and inspection stages, so early-stage DX directly links to improved productivity across the site. In particular, the government-led [i-Construction](https://www.mlit.go.jp/tec/i-construction/index.html) initiative has made the once-unthinkable style of "solo surveying" a real possibility. This article explains the outline of i-Construction and its relationship to surveying DX, the background driving the need for solo surveying, changes in surveying brought by RTK technology and smartphone use, the benefits of using survey data consistently through construction and inspection, and the advantages of new technologies that can be handled by young staff or non-survey specialists. Finally, using the latest smartphone surveying solution LRTK as an example, we show how solo surveying can boost site DX.

What is i-Construction? Its Relation to Surveying DX

i-Construction is a productivity improvement project for construction sites promoted by the Ministry of Land, Infrastructure, Transport and Tourism since 2016. It aims to comprehensively introduce ICT (information and communication technology) across every process from surveying, design, construction, inspection, to maintenance management, reducing labor and time while ensuring quality and safety. The background includes increased construction demand (Tokyo Olympics, Expo, aging infrastructure countermeasures, etc.) and industry challenges such as an aging workforce and lack of young skilled workers, which have caused long-term stagnation in productivity. As part of a "productivity revolution," the government has strongly promoted i-Construction to make it the new norm in the construction industry.

One pillar of i-Construction is the DX of surveying and construction. For example, in earthwork, a combination of automatic drone flight surveying, machine-guided construction equipment, and automated as-built (volume) management has set a goal to improve construction site productivity by 20% by fiscal 2025. The use of 3D data is recommended from initial topographic surveys through construction progress management to final inspections, and 3D laser scanners, photogrammetry, and GNSS positioning technologies have actually been introduced on many sites. In 2024, an advanced version called "i-Construction 2.0" was also formulated, emphasizing further automation of construction sites. The spread of new measurement technologies such as simple yet high-accuracy 3D surveying via smartphone apps is reported within this framework, and these are expected to greatly contribute to efficiency and labor reduction in surveying. In other words, i-Construction is a driving force accelerating "surveying DX," the starting point of site DX.

Site Challenges and Background That Make Solo Surveying Necessary

Until now, surveying work has been commonly performed by a team of multiple people. Typically, one person operates surveying equipment such as a total station, while another stands at the target point with a staff or prism at a distance—this division of roles requires coordinated teamwork and considerable time and effort from setup to teardown. If the number of survey points or the area is large, surveying alone can easily take a full day. Moreover, because this work relied on manual, analog processes, it carried the risk of human error: misreading staff graduations or mistakes in handwritten records can force re-measurement in later stages, increasing costs and delaying schedules. Because of this burden, crews often measured only the most seemingly important spots on large sites, leaving risks of unforeseen problems due to oversights.

Recently, however, the construction industry has suffered from chronic labor shortages and an aging of skilled workers. With fewer experienced survey technicians and stagnating new hires, reducing personnel and improving efficiency in surveying has become an unavoidable issue to operate sites with limited staff. Continuing to rely on “people-dependent surveying” as before has become difficult, and there is strong demand for new methods that can achieve high-accuracy surveying with few people. In this context, the approach of ICT-enabled "solo surveying" is attracting attention. Government-led promotion of i-Construction and the broader trend of construction DX are tailwinds, and the conventional wisdom that "surveying must be done by teams" is beginning to change. From the field, there are voices saying, "If one person can measure accurately, that’s more efficient," and solo surveying is becoming the new norm in an era of labor shortages.

How RTK Technology and Smartphone Use Are Changing Surveying Styles

The major technological enabler of solo surveying is the evolution of GNSS positioning technology. GNSS, represented by GPS which measures positions using satellite signals, has traditionally been used in surveying, but standalone GNSS positioning typically produces errors on the order of several meters, falling short of the centimeter-level accuracy required on construction sites. Enter *RTK* (Real Time Kinematic). RTK links a single rover receiver with a base station at a control point and performs real-time differential corrections of common error factors via communication, dramatically improving positioning accuracy. This makes centimeter-level positioning immediately possible, and since the 1990s RTK has spread as a surveying method that can replace total stations.

Traditional RTK-GNSS equipment tended to be expensive, bulky, and stationary, requiring specialized knowledge to operate. Setting up a dedicated base station and preparing radio communication devices raised the barrier to use, so although accuracy was high, it was not easy to use and did not directly lead to true labor reduction. In recent years, however, miniaturization and cost reduction of RTK-GNSS equipment have progressed, and ultra-compact receivers that work with smartphones have appeared. For example, pocket-sized RTK receivers that can be attached to a smartphone — such as the [LRTK](https://www.lrtk.lefixea.com/lrtk-phone) described later — weighing only about 100–125 g, remove the need to carry tripods or long staffs, enabling one person to perform high-accuracy surveying while moving around the site. Antennas and batteries required for positioning fit in one hand, allowing agile movement in confined or sloped areas, and reducing device burden for older or physically weaker workers.

Furthermore, the use of smartphone apps has transformed surveying styles. Smartphones offer intuitive user interfaces familiar to young workers, and dedicated apps allow positioning and recording with the tap of a button; complex settings and calculations are automated, so accurate data capture is possible even without specialized surveying knowledge. For example, placing the pole tip instrument on the point to be measured and pressing the "Measure" button on the smartphone screen records the latitude, longitude, and elevation at that instant with centimeter-level accuracy (half-inch accuracy). The acquired data is immediately saved in the smartphone, and date/time, point name, and the positioning state (e.g., fixed/FIX) are automatically recorded, enabling reliable digital capture without human error. The app also performs conversions to Japan’s plane rectangular coordinate system and geoid height corrections, so users do not need knowledge of coordinate calculations. In short, the complex behind-the-scenes processing of surveying is increasingly handled by hardware and software, and site personnel can focus on simply "placing the device on the point and pressing a button."

Such real-time and simple surveying not only reduces personnel requirements but also dramatically speeds up operations. Because one person can measure immediately when needed, tasks are no longer interrupted while waiting for the survey team. Instant measurement and data sharing on the spot eliminate time lost to planning and speed up decision-making. For example, if a survey that previously took two people half a day can be completed by one person within a few hours, total man-hours are greatly reduced and the overall schedule gains flexibility. If acquired data can be shared with the office via the cloud in real time, supervisors or colleagues can be informed and give instructions while the surveyor remains on site. Combining RTK technology with smartphones thus enables a new surveying style that balances labor reduction (fewer people) and real-time capability, rewriting the norms of surveying work in site DX.

Benefits of Using Survey Data Consistently Through Construction and Inspection

The high-accuracy digital survey data obtained via solo surveying can be used consistently for subsequent construction planning and quality inspection. This is the key way surveying DX contributes to overall site DX. Traditionally, inefficient rework often occurred—for example, handwritten field notes were later input into CAD drawings at the office, or separate surveys were conducted after completion to create as-built drawings. However, if the initial survey data are digitized and shared via the cloud, handovers to later stages become seamless.

Specifically, point cloud data and coordinate information obtained from surveys can be imported directly into design software for earthwork volume calculations and construction planning. It is easy to overlay the existing 3D terrain model with the 3D design data to simulate construction steps or share the completed-image with all stakeholders. During construction, periodic solo surveys of the current state and comparison with the design model allow instant confirmation of whether the as-built shape matches the design. Color-coding on point clouds visualizes areas of excess or deficit in embankment or excavation, allowing early detection of locations needing rework. This directly improves quality control and prevents rework.

If the latest survey data are constantly uploaded to the cloud, remote site presence from the office becomes possible. For example, high-accuracy current point clouds or 360-degree photos captured by smartphone can be shared via the cloud, allowing headquarters engineers to verify the site in a VR environment. Smooth remote information sharing facilitates explanations and negotiations with clients, speeding up consensus building. At project completion, comparing pre- and post-construction data enables rapid creation of electronic deliverables for as-built records. Digital deliverables compliant with i-Construction guidelines are easier to prepare, streamlining interactions with clients and inspectors.

Thus, realizing DX at the surveying stage not only optimizes surveying tasks but also elevates productivity across construction and inspection processes. By fully utilizing the initial survey data to the end, duplicated work and data inconsistencies are reduced, speeding up the entire site and improving quality. This truly embodies the concept that "site DX starts with surveying."

Advantages as Site Technology Usable by Young and Non-Survey Staff

A major strength of the latest solo surveying technologies is that they are easy for people without specialized skills to handle. If not only survey specialists but also construction managers and craftsmen can perform measurements themselves, the range of work becomes broader. ICT-enabled smartphone surveying offers benefits to young employees and staff in non-survey roles. Key advantages include:

• Intuitive and simple operation: Because the tools run as smartphone apps, people accustomed to using smartphones can operate them without confusion. Following on-screen instructions and pressing buttons is enough to measure, and complex settings and calculations are processed automatically in the background. Newcomers can learn the basic operations with a short lecture and start using them on site the same day.

• Small, lightweight equipment with low burden: There is no need to carry conventional optical surveying instruments or heavy tripods; a smartphone and a small GNSS device suffice. Devices weighing a few hundred grams are easy for older veteran workers to carry. Because the tools are easy to carry on site, ad-hoc measurements for fine checks become routine. This prevents forgotten measurements or deferrals, contributing to improved safety.

• High accuracy even with limited surveying knowledge: Apps visually display current positioning accuracy and satellite reception status, and warn when accuracy is unstable, allowing users to judge the situation while working. Acquired coordinate data is automatically converted to public coordinate systems, so users can obtain high-quality measurement results without specialist knowledge. Even inexperienced staff can achieve results close to veterans, helping standardize technical skill across the organization.

• Multitasking for on-site records: Smartphone surveying devices can do more than capture point positions. For example, combining the phone’s camera or LiDAR can capture surrounding point clouds simultaneously, or AR (augmented reality) features can project design lines from electronic drawings onto the field for stakeout. A single person can measure while taking photo records and confirming as-built conditions in parallel, compressing work steps and improving efficiency.

In this way, solo surveying technology is becoming less the exclusive domain of specialists. Digital-native young workers and even veterans who are less comfortable with digital tools will be pleasantly surprised by the convenience of "measuring with a single tap." When site staff across the board can use the technology, surveying becomes a more familiar, everyday task, and the right person can respond immediately when measurement is needed.

Example of Introducing Smartphone Surveying: How LRTK Brings a Solo Surveying Revolution

Now let’s look at a real example where solo surveying enabled site DX. On a certain mid-sized construction site, a smartphone-mounted RTK positioning system [LRTK](https://www.lrtk.lefixea.com/lrtk-phone) was introduced to replace the previous two-person surveying operations. As a result, survey work hours were reduced by 30% in the first week, and substantial efficiency gains continued thereafter. According to the site manager, after introducing LRTK "fewer people are needed for surveying, allowing deployment of personnel to other important tasks. Because you can measure as soon as you think of it, there are no waits for work to proceed, achieving schedule reduction and quality improvement simultaneously."

LRTK is an ultra-compact smartphone-integrated RTK-GNSS receiver developed by a startup originating from Tokyo Institute of Technology. With a thickness of about 13 mm (0.51 in) and a weight of about 125 g, it can be attached to an iPhone or iPad and provides centimeter-level measurement capability on its own. It comes with a dedicated app and cloud service that immediately plot acquired position information on a cloud map for internal sharing. It supports network RTK (Ntrip), allowing correction data reception from national control station networks via the smartphone’s 4G/5G connection. In areas without network coverage, such as mountainous regions, correction information can also be obtained using high-precision augmentation signals (CLAS) provided by Japan’s Quasi-Zenith Satellite System (QZSS, “Michibiki”), enabling continued positioning even where the internet is unavailable.

LRTK is designed so that anyone can easily perform solo surveying. In the aforementioned site, a first-year employee was responsible for LRTK surveying and picked up the knack of it in a short time, as if operating a smartphone game. From checking the positioning state to saving data and sending it to the cloud, everything is completed with one tap, eliminating the need for paper field notebooks. The results can be imported directly into BIM/CIM and CAD software, making comparison with design drawings and creation of as-built documentation smooth. LRTK is thus a prime example of a solution that greatly improved surveying accuracy and work efficiency on site.

Solutions that meet the i-Construction requirements promoted by the Ministry are being adopted by construction companies and local governments across the country. Introducing just one smartphone surveying device like LRTK to a site will let you experience the immediate benefits. Start by trialing it on a small site or project to feel the effects, and gradually expand its use. Site DX, starting with surveying DX, can be a trump card for resolving labor shortages and improving productivity. "Site DX starts with surveying" — by proactively adopting the latest technologies and embedding the new norm of solo surveying on sites, you can achieve smarter construction management that breaks free from old conventions.