Benefits of Centimeter-Level Positioning: Contributing to On-Site Efficiency and Precision Construction

In recent years, advances in satellite positioning technology have dramatically improved work efficiency and construction accuracy at civil engineering and construction sites. Among these, the "centimeter-level positioning" technology, which can limit positioning errors to within several centimeters (within several in), has attracted attention. In fact, expectations are rising for the introduction of centimeter-level positioning as a trump card for on-site DX (digital transformation) not only among major general contractors but also regional construction companies, surveying technicians, and infrastructure management fields such as railways and roads.

This article outlines what centimeter-level positioning is, explains its mechanisms and how it differs from conventional technologies, and details the concrete benefits it brings to on-site efficiency and precision construction. At the end of the article, we also introduce the latest easy surveying solution "LRTK" that enables convenient use of such high-precision positioning on site.

In particular, i-Construction, advocated by the Ministry of Land, Infrastructure, Transport and Tourism, promotes the use of ICT technologies, and centimeter-level positioning is a key element. Moreover, in the construction industry, which faces chronic labor shortages and challenges in skill transfer, labor-saving and automation through such technologies are becoming indispensable. The introduction of high-precision positioning is an unavoidable trend from the perspectives of improving industry-wide productivity and ensuring quality.

Table of Contents

• What is centimeter-level positioning?

• Benefits leading to on-site efficiency

• Benefits for precision construction

• Easy surveying with LRTK

• FAQ

What is centimeter-level positioning?

As the name suggests, centimeter-level positioning is a collective term for high-precision positioning technologies that keep positioning errors within several centimeters (within several in). With conventional standalone GPS (GNSS) positioning, slight errors in satellite signals and atmospheric effects could cause positions to deviate by several meters (several ft). That is sufficient for everyday car navigation or smartphone map apps, but errors of several meters are unacceptable for the precise construction required at construction sites. For example, surveying for building foundations or road centerlines cannot proceed if positions are off by 3 m (9.8 ft). Enter centimeter-level positioning technology, which dramatically reduces positioning errors.

A representative method for achieving this high-precision positioning is RTK (Real-Time Kinematic). RTK operates two GNSS receivers simultaneously: a base station installed at a known coordinate and a rover that performs positioning while moving. The two units exchange satellite data received via radio or communication lines in real time, and the error information obtained at the base station is applied as corrections to the rover’s positioning solution, shrinking positional deviations that were normally several meters down to within several centimeters (within several in). In short, by comparing the positional differences between two receivers, errors cancel out and an order-of-magnitude improvement in accuracy is achieved.

Besides RTK, technologies such as PPP-RTK and CLAS (Centimeter-Level Augmentation Service), which enable a single receiver to receive high-precision augmentation signals from satellites, have also been put into practical use. For example, in Japan, by utilizing augmentation information via the Ministry of Land, Infrastructure, Transport and Tourism’s Geodetic Reference Station Network and the Quasi-Zenith Satellite System Michibiki, an environment has been established in which centimeter-level positioning is possible without installing your own base station. In addition, mobile carriers are advancing the provision of high-precision positioning services, and an era is approaching in which the GPS receivers built into smartphones can directly utilize centimeter-level accuracy (cm level accuracy (half-inch accuracy)). As a result, precision positioning that once required specialist surveyors and expensive equipment can now be more easily incorporated into daily operations. Beyond civil engineering and construction, application areas are expanding to include autonomous agricultural machinery, drone surveying, and infrastructure inspection, making high-precision positioning an increasingly familiar technology year by year.

Benefits leading to on-site efficiency

Introducing centimeter-level positioning to the site significantly improves the efficiency of surveying and construction management tasks. Here are some representative benefits.

• Faster surveying work: Surveying tasks that used to take a long time with specialized equipment or conventional methods are greatly accelerated. With RTK-GNSS, continuous positioning while moving is possible within a clear line of sight, so on a large site, a single person can complete surveying simply by walking around and collecting points. This eliminates the need to set up tripods repeatedly like with total stations or to have multiple people lay out positions, dramatically shortening task time. In addition, positioning data can be checked on the spot, reducing the time required for calculations and data organization back in the office.

• Cost reduction through labor savings: Because high-precision positioning can be performed by fewer personnel, it helps alleviate labor shortages and reduce labor costs. Tasks that previously required multiple people for installing batter boards or measuring as-built conditions can increasingly be handled by one person from surveying to recording using centimeter-level positioning equipment. As a result, survey outsourcing fees and personnel costs can be reduced, contributing to lower overall construction costs. Also, experienced technicians no longer need to be tied up for long periods performing surveys and can concentrate on core construction management tasks.

• Improved safety (reduction of hazardous work): There are safety benefits in addition to efficiency gains. Because high-precision positioning allows surveys to be completed in a short time, workers do not need to spend long hours at hazardous locations such as roadsides with heavy traffic or steep slopes. Combining this with drones enables remote measurement of areas where people cannot enter. This helps reduce on-site risks and improve safety. Furthermore, preventing accidents helps reduce industrial accidents, contributing to a safer working environment.

These improvements can shorten overall construction schedules and reduce personnel costs. In fact, case studies promoted by the Ministry of Land, Infrastructure, Transport and Tourism show that introducing RTK positioning reduced the time required for surveying and construction management by 20–30% compared to conventional methods. By leveraging centimeter-level positioning, you can significantly improve on-site productivity, mitigate labor shortages, and achieve shorter construction times and better cost control.

Benefits for precision construction

The greatest advantage of introducing centimeter-level positioning is a dramatic improvement in construction accuracy. With conventional GPS or manual positioning, small surveying errors could later translate into misalignments or construction mistakes in structures. High-precision positioning, however, keeps coordinate errors to within a few centimeters (within several in), allowing construction to proceed at the designed positions and dimensions.

For example, positioning building columns or bridge piers based on measurements from centimeter-level positioning can minimize human-induced positional deviations. Centimeter-level positioning also excels in as-built management. If the terrain after embankment or concrete placement is surveyed with RTK-capable equipment, high-density 3D shape data can be acquired quickly, allowing immediate identification of differences from design data. The Geospatial Information Authority of Japan’s prescribed as-built measurement methods note that using RTK-GNSS makes it easier to keep measurement results within allowable errors, and it is effective for ensuring quality.

In one real-world case, RTK recorded an accuracy of less than 10 mm (0.39 in) in horizontal position, a level that was previously difficult to achieve. If positioning can be accomplished with errors of about 1 cm or less (about 0.4 in or less), minute tilts or displacements of structures that were previously undetectable can be identified, raising the level of quality control significantly.

High-precision positioning also proves valuable for maintenance and management after construction is completed. Regular monitoring surveys can capture minute settlement or displacement of bridges and ground, enabling early repairs and contributing to safety assurance.

Furthermore, centimeter-level positioning is not merely a means of improving surveying accuracy but serves as a foundational technology supporting ICT construction and DX promotion in the construction industry. i-Construction and CIM (Construction Information Modeling), advocated by the Ministry of Land, Infrastructure, Transport and Tourism, emphasize the use of 3D data on site, and centimeter-level positioning, which acquires highly accurate positional information, is indispensable for these initiatives.

For example, if GNSS receivers are mounted on construction machinery such as bulldozers and excavators, the machines’ positions and heights can be known in real time within a few centimeters (within several in), enabling machine control that limits construction errors to within a few cm (within a few in). This paves the way for future unmanned or robotic construction.

Also, advanced construction management approaches—such as overlaying a design model on the site using AR technology to check as-built conditions on the spot—are realizable only with highly reliable positional information. Introducing centimeter-level positioning is a first step toward a new era of precision construction and smart site operations that fully leverage digital technologies.

Easy surveying with LRTK

Finally, we introduce "LRTK" as an easy-to-use solution that realizes centimeter-level positioning. LRTK (LRTK) is a modern easy-surveying system composed of a pocket-sized, lightweight GNSS receiver and a smartphone app. With this single device, you can handle centimeter-level positioning on site, 3D scanning, and position layout work using AR, making it a truly versatile surveying tool.

The LRTK receiver weighs only a few hundred grams and has a built-in battery, communicating wirelessly with a smartphone. On site, you simply attach a smartphone and the receiver to the tip of a dedicated pole (monopod) and walk around, allowing one person to survey efficiently. Operation is simple—high-precision positioning can be started by following button operations and on-screen prompts—so even beginners can use it without confusion.

In terms of accuracy, LRTK achieves centimeter-level accuracy (cm level accuracy (half-inch accuracy)) comparable to higher-end surveying equipment. It delivers high accuracy of about 1–2 cm (0.4–0.8 in) in horizontal position and within a few centimeters (within several in) in height, so height measurements that were difficult with conventional GPS are no problem. LRTK also supports augmentation signals such as those from Quasi-Zenith Satellites, maintaining high precision even in mountainous areas where mobile communications are unavailable or at emergency sites during disasters. In practice, LRTK has been used for surveying disaster sites by local governments, proving its reliability. Of course, in private construction sites, site supervisors and construction managers are increasingly carrying LRTK to perform necessary surveying and as-built checks immediately, creating new operational workflows.

LRTK’s software features are also comprehensive. For example, it provides 3D point-cloud scanning using a smartphone’s LiDAR or camera to measure site objects, AR functionality that overlays design data to guide users to prescribed positions, and cloud-sharing of acquired positioning data for immediate team verification—functions that previously required separate devices and processes are now realized on a single platform.

By introducing LRTK, companies can obtain data quickly in-house while reducing surveying outsourcing costs. Site staff can conduct surveys when needed, reducing waiting time for specialists and preventing delays in construction scheduling. Furthermore, moving away from chalk-line layout based on paper drawings and craftsmanship intuition to reproducible, data-driven construction makes higher-quality work with fewer personnel possible. As a result, companies can simultaneously improve quality control and reduce costs, offering significant managerial benefits. Initial introduction costs are also lower than those of conventional surveying equipment, making LRTK accessible for small and medium-sized enterprises.

For example, at a certain road construction site, introducing LRTK reduced as-built measurement work that used to require two people and more than half a day to one person completing the task in a few hours. The site supervisor was able to perform surveying and quality checks in a short time, dramatically improving overall construction efficiency and quality management.

By wisely leveraging centimeter-level positioning technology, you can dramatically enhance productivity and quality at construction sites. Consider adopting innovative solutions like LRTK to evolve your sites to the next stage.

FAQ

Q: How does regular GPS positioning differ from centimeter-level positioning? A: Regular GPS (standalone positioning) can have errors of several meters, whereas centimeter-level positioning limits those errors to within several centimeters (within several in). The latter uses correction techniques such as RTK to remove error sources from satellite signals, resulting in dramatically improved positioning accuracy.

Q: Do I need dedicated equipment to use centimeter-level positioning? A: High-precision positioning requires dedicated equipment such as GNSS receivers that support RTK. Traditionally, a two-unit set of a base station and a rover was common, but systems that allow centimeter-level positioning with only a rover by using the Geodetic Reference Station Network or satellite distribution services have become widespread. Products like LRTK that combine a small receiver and a smartphone app to easily achieve cm level accuracy (half-inch accuracy) have also appeared.

Q: What kinds of sites and tasks benefit from centimeter-level positioning? A: It is most effective in situations where structures must be constructed at design positions. Examples include chalking out building foundations, road centerline surveying, managing cut-and-fill volumes in land development, and aligning positions during bridge installation—important surveying and construction tasks where a few centimeters of deviation are unacceptable. It is also useful for as-built measurement and displacement monitoring after construction. Beyond construction, centimeter-level positioning is applicable to precision agriculture with autonomous farm machines, drone surveying for high-precision mapping, and many other fields.

Q: Is operating centimeter-level positioning difficult? Do I need specialist knowledge? A: Recent high-precision positioning systems are designed to be user-friendly and can be used without advanced specialist knowledge. While conventional surveying instruments required time to master, modern solutions like LRTK offer simple operation apps and guidance features, allowing first-time users to intuitively perform positioning tasks. Once basic operation methods are learned, centimeter-level positioning can be used on-site without special qualifications.

Q: Can centimeter-level positioning be used in places where satellite signals cannot be received? A: In principle, GNSS positioning cannot be used in environments where satellite signals cannot reach. Therefore, centimeter-level positioning cannot demonstrate accuracy inside tunnels, inside buildings, or in forests where the sky is not visible. In urban areas surrounded by tall buildings, satellites may be blocked and positioning can become unstable. In such environments, measurements using other surveying instruments like total stations are necessary. On the other hand, typical outdoor civil engineering and construction sites usually have sufficient sky visibility to utilize GNSS-based high-precision positioning. In Japan, the use of the Quasi-Zenith Satellite System (Michibiki) has improved satellite positioning availability even in urban areas, but positioning is still difficult in completely roofed-over locations.

Q: How much does it cost to introduce centimeter-level positioning? A: Introduction costs vary depending on the chosen system and equipment, but prices have become significantly more affordable in recent years. Previously, a full set of high-precision GNSS equipment could cost several million yen, but lower-priced products are now available. In addition, efficiency gains and reductions in surveying outsourcing fees contribute to cost savings, so the investment can often be recouped in a relatively short period. Specific prices depend on features and service content, but the barrier to entry has lowered to a level manageable even for small- to medium-sized sites. Moreover, in Japan, the CLAS augmentation signals provided free of charge from the Michibiki satellites are being developed, expanding environments in which centimeter-level positioning can be used without a communication line.

Q: Does high-precision positioning take a long time? A: With the RTK method, positioning calculations are performed in real time, so it does not require special time. After powering on the receiver, an initial convergence time of several tens of seconds to a few minutes (the time to align error information from satellites) is required, but once centimeter-level accuracy is obtained, you can continue to receive high-precision coordinates immediately while moving. In other words, you can progress surveying from point to point without waiting at each location.

Q: Do weather or time of day affect positioning accuracy? A: Basically, GNSS positioning can be performed with the same accuracy day and night. Satellite motion does not differ between day and night, and darkness is not a problem. Weather such as cloudy skies or moderate rain has little effect on radio waves, and accuracy hardly deteriorates. However, in the event of extreme conditions such as typhoons causing heavy rain or abnormal radio disturbances like solar flares, positioning may become temporarily unstable. Under normal conditions, you can use centimeter-level positioning stably regardless of weather or time of day.