Chrono Locate™ positioning technology enables accurate location tracking indoors, underground, and in other non-GNSS environments
April 01, 2026
Taisei Corporation
Seiko Group Corporation
Taisei Corporation (President and CEO: Yoshiro Aikawa) and Seiko Future Creation Inc. (President and CEO: Makoto Ichimura) and Seiko Solutions Inc. (President and CEO: Jun Sekine), operating companies of Seiko Group Corporation (Chairman, Group CEO and Group CCO: Shinji Hattori), have jointly conducted a test to demonstrate Seiko’s Chrono Locate™ indoor high-precision positioning system² at construction sites. The system enables highly accurate positioning even indoors or underground, where Global Navigation Satellite Systems (GNSS)¹ cannot be used.
GNSS has added significant capabilities to construction sites, including more efficient surveying operations, ICT-enabled construction, and digitalization of as-built/inspection management. Through this initiative, the partners aim to extend these same capabilities to non-GNSS environments. Leveraging the high accuracy and compact size of Seiko’s Chrono Locate™, the parties also envision deploying the technology as one of the applications on Taisei’s integrated platform, “T-iDigital Field,” as described below.
Specifically, by combining the system with advanced technologies such as augmented reality (AR), it becomes possible to support high-precision drone surveying, AR visualization of 3D design drawings, and enhanced safety management (through worker movement tracking), while also enabling high-precision positioning and monitoring of heavy equipment and construction machinery. This can supplement the measurement and confirmation processes that workers have traditionally performed by using surveying instruments to determine equipment positions.
The demonstration confirmed that the system can acquire highly accurate 3D positional information in real time. This makes it possible to advance construction operations and improve productivity even in non-GNSS environments.
Going forward, the partners aim to use this technology to help address the problem of skilled labor shortages at construction sites, while at the same time improving productivity and safety.
Across the construction industry, initiatives are underway to dramatically improve site productivity through proactive use of ICT and IoT devices, including the government-led “i-Construction” program. One key tool is GNSS, which is widely used in everything from topographic surveying and civil engineering support to operation management of construction machinery and dump trucks. GNSS is necessary to acquire accurate positioning information and drive digital production processes.
However, GNSS can only be used in areas that can receive satellite radio waves. In other places, such as tunnels or underground construction sites, or in places prone to signal reflections, GNSS is not reliable. Accordingly, there has long been a need to develop new systems that can obtain accurate positioning information in any location, above ground or below ground.
In response, Taisei turned to Seiko’s Chrono Locate™ technology, a new positioning technology that does not require satellites. Taisei launched a demonstration of this technology together with its integrated platform, T-iDigital Field, with an eye toward using it at construction sites.
This technology enables simultaneous nanosecond-level time synchronization and centimeter-level measurement — capabilities that have traditionally been difficult to achieve — by installing multiple base stations in the target area to determine the position of mobile stations. Whereas GNSS is based on one-way reception of satellite radio signals, this technology measures distance by calculating the difference in arrival times of bi-directional radio signals — both the base stations and mobile stations transmit and receive radio signals bi-directionally*3. By using this bi-directional communication to synchronize time codes between devices with nanosecond-level precision, Chrono Locate™ can calculate position accuracy down to the centimeter.
The mechanism can best be described as a “localized GPS,” a system that brings GNSS-like functionality to any location. By installing multiple base stations in the target area, the system can calculate the position of one or more mobile stations with extremely high accuracy.
Outline of the Demonstration
Site
Metropolitan Expressway Inner Circular Route (Nihonbashi Section) Tokiwabashi District Tunnel Construction – part of the underground work for the Nihonbashi section of the Expressway (Client: Metropolitan Expressway Company Limited; Contractor: Taisei Corporation-Kawada Industries JV).
A positioning test using Chrono Locate™ was conducted under the elevated expressway in Tokyo between Chiyoda-ku and Chuo-ku — an environment chosen because GNSS signals could not be received there.
Method
Twelve base stations were installed within the work area under the elevated expressway, and a tracking test was conducted for a work boat (a mobile station) traveling on the Nihonbashi River.
In addition, a test was conducted to locate a backhoe attached to a barge (used for dredging work). Mobile stations were installed at the operator’s seat and at the rear of the equipment, and a test was conducted to track the boom’s swing motion.
Results
(1) The positioning data of the work boat closely matched the results of laser surveying, confirming excellent positioning accuracy. By combining data from multiple areas, the system smoothly covered a wide work area and enabled continuous positioning even when the boat moved through different locations.
(2) Using two mobile stations mounted at the front and rear of the backhoe, the test confirmed that the boom’s swing motion could be tracked continuously. The results indicate potential future application to accurately determine dredging positions.
Going forward, Taisei plans to implement positioning functions using this technology as one of the applications on its T-iDigital Field integrated platform, which uses digital technologies to support construction management on-site. This will enhance as-built results, quality, and safety management in non-GNSS environments and promote the digital transformation of the entire construction process.
Seiko plans to expand this technology beyond construction and civil engineering applications to a variety of industrial fields, including optimizing product transportation lines in logistics warehouses and factories where GNSS signals do not reach, and controlling automated transport robots. Through these efforts, Seiko will contribute to improving productivity and building new social infrastructure by leveraging accurate positioning information.
Photos: Demonstration test(work boat tracking)
Photos: Demonstration test (backhoe barge operation)
- ¹ GNSS (Global Navigation Satellite System): A collective term for satellite-based positioning technologies that receive radio signals transmitted by positioning satellites — such as GPS (U.S.), QZSS (Japan), GLONASS (Russia), and Galileo (EU) — to provide accurate location and time information.
- ² Chrono Locate™ is a trademark of Seiko Group Corporation (application pending). Its positioning system employs Seiko’s proprietary high-precision time synchronization technology. The system instantly combines distance information obtained from at least four base stations to accurately identify the 3D position (XYZ coordinates) of a mobile station.
- ³ This technology incorporates research results from Japan’s National Institute of Information and Communications Technology (NICT), a National Research and Development Agency.
For media inquiries:
Taisei Corporation, Corporate Communications Department, Public Relations Office
+81-3-5381-5011
Seiko Solutions Inc., Marketing Communications Department
+81-3-6779-8952