LRTK Transforming Railway Signaling and Communications: Accelerating On-site DX with Smartphone RTK × AR

Introduction: On-site Challenges in Railway Signaling and Communications and the Need for DX

The field of railway signaling and communications is the unsung backbone that supports safe train operations. Signals, turnouts, cables, and many other pieces of equipment along the track monitor the railway around the clock. However, construction and maintenance sites still heavily rely on analog/manual work, presenting challenges in both efficiency and safety. In particular, the burden of nighttime work is significant: operations must be concentrated into the narrow window between the last and first trains (generally from around midnight to the early morning hours, typically midnight to about 4:00 AM). Working in the dark with limited personnel while relying on paper drawings for construction and inspection carries a high risk of mistakes and forces dependence on veteran intuition. With the aging workforce and labour shortages across the rail industry, the need for on-site DX (digital transformation) using digital technologies is increasing. On-site DX refers to initiatives that use digital tools to streamline and enhance fieldwork. In the railway signaling and communications domain, DX is strongly expected to improve productivity and reduce human error.

Inefficiencies and Constraints in Traditional Construction, Inspection, and Design Management

Until now, many processes in railway signaling and communications construction and maintenance inspections have depended on manual work and experience. For example, laying out the position of a new signal post required surveying teams to use measuring tapes and optical surveying instruments (such as total stations), measuring distances from reference points alongside the track multiple times at night and marking locations. Determining positions while holding paper drawings and illuminating them with a flashlight is cumbersome and prone to human error. Because work had to be tackled through manpower-intensive approaches, it depended on the instincts of skilled workers, making it person-dependent and hard to standardize.

Inspection work is similarly handled by referring to paper logbooks and drawings on site. For instance, confirming a communication cable route required comparing printed wiring diagrams with the actual installation to find anomalies, which is not efficient in the field. Spreading paper drawings out for verification within the limited night-time work window is highly inefficient, and dim conditions increase the likelihood of recording mistakes.

Furthermore, the traditional slowness of data sharing was also a bottleneck. Notes and photos taken on site had to be reorganized back at the office and reflected into reports and drawings. This time lag sometimes meant that measurements taken on site were not accurately recorded, or the latest information did not reach all departments. Paper-based management tends to fragment and scatter information, and measurement results obtained overnight often go underutilized.

In short, railway signaling and communications sites have faced a double inefficiency of “labor-intensive nighttime work” and “paper-based drawing management.” To break through this situation and maintain infrastructure safely and reliably, operational innovation using the latest technologies is indispensable.

Smartphone RTK × AR × 3D Scan “LRTK” Features and Integration

One solution to these challenges is the positioning system “LRTK,” which leverages smartphone RTK × AR technology. LRTK is our company's system that equips a smartphone with a compact high-precision GNSS receiver to enable centimeter-grade positioning. By combining a smartphone with a dedicated antenna, users can achieve accuracy comparable to surveying equipment that previously cost hundreds of thousands of dollars, making such precision accessible to anyone.

LRTK has three major features. The first is smartphone RTK positioning. RTK (Real Time Kinematic) is a technique that obtains high-precision positions by applying real-time corrections to satellite positioning errors, and smartphone RTK makes this technology available on smartphones. Normal smartphone GPS has errors of several meters, but LRTK improves accuracy to within a few centimeters by using network-based electronic reference station data and augmentation signals from the Quasi-Zenith Satellite “Michibiki.” The smartphone screen displays real-time coordinates of the current location, and pressing a button at a point to be measured captures and saves its 3D coordinates. Surveying that once required multiple people can now be completed by a single person with a smartphone.

The second feature is AR (augmented reality) visual guidance. Through the camera view of the LRTK-compatible app, design data and guidance markers can be overlaid onto the real-world scene. Thanks to high-precision RTK positioning, digital information is placed without drift relative to the user's position and orientation, so an on-site virtual AR marker can be displayed exactly where “a signal post should be installed.” What used to require measuring dimensions on drawings, driving stakes, and many steps can now guide workers to the precise point simply by following arrows on the smartphone screen. Cable routes and other paths can also be drawn on the ground as AR lines or arrows, allowing intuitive understanding of routes that are hard to visualize on paper. AR displays are visually prominent even in dark sites, enabling quicker and more accurate decisions during nighttime work about “which part to replace” or “which route to lay the cable.”

The third feature is 3D point cloud scanning. Modern smartphones include LiDAR sensors and high-performance cameras that can scan surrounding structures and record them as collections of points (point cloud data). LRTK combines this point cloud measurement with RTK positioning to attach accurate position coordinates to scanned objects and save them. For example, after installing a signal post, scanning around the post with a smartphone records 3D data showing the post’s height, tilt, and spatial relationships to surroundings, which is automatically saved to the cloud. Previously, point clouds captured by laser scanners required specialist work on PCs to merge and process them, but with LRTK a field worker can obtain an as-built 3D model simply by waving a smartphone.

These smartphone RTK positioning, AR, and point cloud scanning functions are useful individually, but LRTK is designed to integrate them within a single app. In other words, “measure, view, and record” can be executed seamlessly with one smartphone. For example, a smartphone equipped with LRTK can measure reference point coordinates in survey mode, then switch to AR mode to display the designed signal equipment model on site for position confirmation, and then use point cloud mode to scan and record the completed structure without interruption. Captured coordinate data, point clouds, and photos can be shared to the cloud instantly and checked on office PCs in near real time. The ability to cross-check design data with on-site conditions in real time and complete recording in one workflow is LRTK’s greatest strength.

LRTK Use Scenarios for Signal Post Installation and Cable Route Management

Now let’s look at representative scenarios showing how LRTK can be effective in concrete field tasks related to railway signaling and communications.

● Use for signal post installation: When erecting or replacing signal posts (signal poles), accurate layout and vertical installation are essential. Traditionally, survey teams calculated offsets and heights from the track center, marking installation points with stakes or chalk. With LRTK, design data for post locations can be loaded into the smartphone in advance and displayed as AR markers on site. Workers can identify installation points within a few centimeters by checking the virtual post model or ground markers on the smartphone screen. Numeric guidance such as “0.05 m east and 0.10 m north of the specified position” can be displayed, eliminating the need to pull a tape measure. After erecting the post, scanning the area with a smartphone records the as-built condition in point cloud data, including post tilt and height. This allows later digital verification of foundation embedding depth and signal height against the design, helping to prevent reinstallation. Point cloud data is also useful for future maintenance: comparing current scans with past point cloud models lets you quantitatively assess changes such as post tilting over time.

● Use for cable route design and management: LRTK is also highly effective for planning and installing signal communication cable routes. Traditionally, determining cable routes required walking the site with paper wiring diagrams and marking routes while taking into account terrain and interference with other facilities. With LRTK, CAD drawings or GIS-based cable routes can be preloaded into the smartphone and projected onto the ground via AR. On site, virtual cable lines appear on the screen, so workers can simply follow them for trenching and wiring. For example, if a route is planned to run south along the track from the station premises to connect to signal X, that route will be shown as a line on the ground through the smartphone view, with turns and junctions clearly visible. This removes the need to compare paper diagrams while measuring, enabling accurate route installation in a short time even during nighttime work.

In addition, LRTK is useful for recording buried cable locations. Until now, records of buried and backfilled cables were typically kept with photos and handwritten notes. With LRTK, you can scan the cable before burial to convert it into a point cloud and upload it to the cloud, thereby recording the cable’s 3D position with high precision. For example, you can save complete point cloud data showing “the communication cable from signal A to B and its depth and route.” This data can later be visualized with AR during other construction that requires digging nearby. By simply holding up a smartphone, the buried cable’s position and depth can be seen through the pavement, greatly reducing the risk of accidental damage and enabling safer, more efficient excavation. LRTK truly serves as a tool to “digitally map” the railway signaling and communications cable network and make it intuitively understandable to anyone.

● Use for maintenance and inspection: LRTK is also powerful for routine inspections and troubleshooting of signaling and communications equipment. For instance, during nighttime inspections, displaying AR markers for “parts scheduled for replacement” or “bolts that need adjustment” allows workers to locate targets without hesitation even in the dark. Imagine the next bolt to be tightened or the cable connection point highlighted with a glowing marker. This reduces time spent searching on site and makes the most of short work windows. Also, if photos with attached position coordinates taken with LRTK are left in the cloud, the office can later accurately determine “which part of which signal was inspected.” This prevents misreading of field notes or mislabeling of photos and streamlines report preparation. Cloud-stored data accumulates as a history, enabling advanced analyses in the future such as overlaying past inspection photos in the same viewpoint via AR for comparison.

Effects of LRTK Adoption: Improved Safety, Accuracy, Efficiency, and Record Integration

Through the scenarios described above, LRTK brings many benefits to railway signaling and communications sites. The main effects of adoption are summarized by point below.

• Improved safety: High-precision positioning and AR guidance reduce work time, decreasing the total time spent working alongside tracks at night. This lowers the frequency of entering hazardous areas and reduces worker exposure risks (such as passing trains and unstable footing). Visualizing buried cables with AR prevents accidental damage during excavation and directly contributes to safety assurance.

• Improved accuracy: RTK positioning achieves accuracies on the order of a few centimeters, dramatically improving the accuracy of signal post layout and cable routing. This greatly reduces mistakes that would require repositioning after installation. Since design data and on-site conditions can be continuously cross-checked in AR, deviations during construction can be detected and corrected immediately, minimizing departures from quality standards.

• Improved efficiency: With one smartphone per person, surveying, layout marking, and inspection can be handled, allowing small teams to operate even amid labour shortages. Intuitive on-screen guidance enables even non-experts to perform tasks, shortening training time. As a result, task durations are reduced and more work can be completed within the limited window between the last and first trains. Labor savings and time reduction also help ease overtime and night-shift burdens.

• Improved recordability: Measured coordinate data, point clouds, and photos are automatically saved and aggregated in the cloud, reducing omissions in records. Manual transcription to paper forms and post hoc data entry are unnecessary, essentially eliminating human error. Keeping inspection histories and as-built records in time series creates a digital archive useful for later root-cause analysis and future planning.

• Information sharing via cloud integration: Data acquired with LRTK can be shared instantly with stakeholders via the cloud. Values measured on site can be shared with the office immediately, enabling real-time guidance. Coordinate and point cloud data collected by multiple field teams can be managed centrally in a global coordinate system, making it easy to integrate data later for wide-area analysis. Connecting field sites and remote offices digitally speeds up reporting and approval processes and promotes organization-wide DX.

As described above, adopting LRTK positively impacts safety, accuracy, efficiency, recordkeeping, and information sharing, elevating overall work quality and productivity in railway signaling and communications.

Conclusion: Applications for Simple Surveying and the Future of On-site DX

Introducing the smartphone RTK × AR solution “LRTK” into railway signaling and communications sites directly addresses current challenges and serves as a first step toward broader DX deployment. LRTK can be applied beyond signaling and communications to various tasks in railway construction such as simple surveying, structural inspections, and management of other infrastructure assets. For example, it can be used for clearance measurements near tracks, catenary pole height checks, and station facility layout surveys, and it is already demonstrating results in other fields. The era of “anyone can be a surveyor with a single smartphone” is becoming a reality at railway worksites as well.

With MLIT-led infrastructure DX initiatives and technological innovation across railway companies, field digitization will accelerate further. In that context, early adoption and utilization of easy-to-use, high-precision tools like LRTK strengthen not only operational efficiency but also corporate competitiveness. Transitioning tasks that once relied on seasoned workers’ intuition to data-driven smart construction will reduce nights spent fearing mistakes and help build a safe, resilient railway infrastructure maintenance system.

On-site DX for railway signaling and communications has only just begun, but its effects are already becoming tangible. Please consider proactively adopting the latest technology with “LRTK.” With the new power of smartphone RTK × AR, bring revolutionary efficiency and peace of mind to your sites and step into the next generation of railway infrastructure management.