Table of Contents

• What is RTK? Overview of Real Time Kinematic positioning

• Importance and challenges of utility mapping

• Innovations mobile RTK brings to field surveying

• Practical recording of asset positions with RTK

• Effects of introducing mobile RTK: improved efficiency, reduced manpower, increased safety

• Conclusion: Simple surveying realized by LRTK

• FAQ

What is RTK? Overview of Real Time Kinematic positioning

RTK stands for Real Time Kinematic, a high-precision positioning technique using GNSS (Global Navigation Satellite Systems). Standard GPS/GNSS positioning typically has errors on the order of several meters due to atmospheric and satellite orbit errors. RTK surveying operates two receivers simultaneously: a highly accurate reference receiver known as the base station (with precisely known coordinates) and a rover (the device being positioned). By using the difference between their received data, RTK corrects errors in real time. When the rover receives correction information transmitted from the base station, error sources contained in satellite positioning are canceled out, enabling position determination with centimeter-level (half-inch-level) accuracy.

In Japan, network RTK based on the Geospatial Information Authority of Japan’s permanent GNSS reference station network (GEONET) is widely used. If the rover connects to a correction data distribution service over the Internet using a protocol such as Ntrip, real-time correction data can be obtained without setting up your own base station. With network RTK, a stable “fixed solution” can typically be obtained within several tens of seconds to about one minute, after which position updates continue at about 1-2 cm (0.4-0.8 in) accuracy. In recent years, the QZSS “Michibiki” satellite system has also introduced a centimeter-level augmentation service (CLAS); by using a compatible receiver, you can receive correction signals directly from satellites even in mountainous areas outside cellular coverage, maintaining high accuracy. Because this enables RTK positioning anywhere in the country without relying on communication infrastructure, it is powerful for surveying during disasters and in remote locations.

RTK-GNSS technology has long been used in civil engineering and construction—for example, in land boundary surveys, as-built control, and machine guidance for heavy equipment—and its high precision has become indispensable for improving field productivity. Traditionally, however, using RTK in the field required expensive dedicated GNSS receivers and radio equipment, and operating them required specialized knowledge. Advances in technology have recently enabled RTK positioning by combining smartphones or tablets with small GNSS receivers. This approach, often called “smartphone RTK,” has drastically reduced the initial investment that once ran into the hundreds of thousands of dollars, and the equipment is now compact, lightweight, and easy to operate. It is becoming possible for non-specialists to leverage centimeter-level positioning in the field with ease.

Importance and challenges of utility mapping

Utilities (lifeline assets) such as potable water pipes, sewer pipes, gas lines, and power cables are often buried deep underground or distributed across wide areas, so accurately knowing and managing their locations is critically important. If the locations of buried pipes are unclear, they can hinder future maintenance and other construction work. Inaccurate location information for aboveground assets such as utility poles and manholes can impede rapid situational assessment during disasters and interfere with digital management of urban infrastructure. Consequently, it has become increasingly important to record precise coordinates of each asset in as-built drawings and asset ledgers, making surveying an essential part of infrastructure asset management.

In fact, it has become more common in sewer works to specify the geodetic coordinates of manholes and pipelines on as-built drawings. Insufficient records of buried objects can lead to severe accidents—such as accidental damage to gas pipes during later excavation—so precise surveying records are indispensable from a safety-management standpoint.

Traditionally, marking and recording the locations of buried objects in the field centered on manual methods using tape measures and total stations. For example, recording the route of buried pipes required measuring offset distances and angles from known reference points one by one and plotting them on drawings. Determining the position of a manhole often required multiple measurements from a site reference point and subsequent coordinate calculations, which was cumbersome. For aboveground assets like utility poles, positions were often estimated relative to land-survey maps or surrounding landmarks, causing discrepancies between actual locations and drawing information. These conventional methods are time-consuming due to manual measurement and recording, and accuracy can vary depending on worker skill. There is also a high risk of human error when handwritten field notes are later transcribed. When construction schedules are tight, surveying may be postponed, and once soil is backfilled it becomes difficult to determine the exact location—another common problem.

With the Ministry of Land, Infrastructure, Transport and Tourism’s push for i-Construction, there is strong demand in the infrastructure sector for digitalization and efficiency from construction through maintenance. In utility asset management, it is desirable to record the locations of buried items and structures as three-dimensional coordinates to enable unified GIS management and support maintenance planning in the future. One effective means to achieve this is RTK positioning using high-precision GNSS.

Innovations mobile RTK brings to field surveying

The advent of mobile RTK technology using smartphones is starting to dramatically change field surveying methods. By attaching a compact RTK-GNSS receiver to a smartphone or tablet, field personnel can now perform centimeter accuracy (half-inch accuracy) positioning easily, allowing site staff to carry out tasks that previously required a dedicated surveying team. There is no longer a need to prepare one expensive dedicated unit and work sequentially; rather, a “one-person-one-device” approach is possible, enabling parallel work. As a result, surveying ceases to be a bottleneck even on large sites, and productivity increases dramatically.

Mobile RTK systems operate via dedicated apps, so recorded points are plotted on a map and displayed on the screen on the spot. Unlike traditional paper-based sketching, an intuitive interface immediately alerts you to missed measurements or omissions. Measurement data are saved digitally in real time and can be shared within the organization via the cloud as soon as collection is completed on site. This eliminates the need to return to the office to transcribe or digitize data, keeping the field and office continuously up to date.

The miniaturization and simplified operation of equipment also provide safety benefits. There is no need to carry heavy surveying gear or spend long times on setup, reducing the physical burden on workers and shortening exposure times in narrow roads or deep excavation sites. The use of mobile RTK thus brings innovations in both efficiency and safety and strongly supports the digital transformation (DX) of infrastructure management.

Practical recording of asset positions with RTK

Let’s look at concrete methods for recording utility assets using mobile RTK and the advantages they offer. By leveraging the high-precision coordinates obtained with RTK-GNSS, you can efficiently digitize a wide range of asset information—from buried pipes to aboveground structures.

埋設管のルート測量 (Route surveying of buried pipes): When laying water, sewer, or gas pipes, it is necessary to record the pipe route accurately in the as-built drawings. By carrying a pole fitted with an RTK-GNSS receiver and recording measurement points at regular intervals while tracing the pipe line directly above the buried pipe, you can map the pipe route with centimeter-level (half-inch-level) precision. In open-cut construction, if you perform continuous measurements from the ground directly above the pipe before backfilling, you can later supplement information such as pipe diameter and burial depth to produce accurate 3D position data. Taking dense points at key locations such as pipe bends and joints makes it easy to faithfully reproduce the piping system on as-built drawings. Coordinates obtained by RTK are referenced to public coordinate systems (projected plane coordinates or geodetic latitude/longitude), so it is easy to overlay them with other survey results or GIS data. Compared with paper sketches, not only is positional accuracy greatly improved, but you also obtain digital asset records that remain useful over the long term.

Surveying buried pipes can be performed efficiently by a single person. By shouldering a pole with an RTK receiver and walking along the trench while measuring, many points can be recorded in a short time even across a wide construction area. Tasks that used to require two people operating a tape measure can be greatly simplified because RTK allows one person to obtain coordinate positions directly.

Manhole position and elevation recording: Manholes in sewer systems can also be surveyed accurately using RTK. If you place the pole tip at the center of the manhole cover, planar position can be obtained with errors within a few centimeters. Whereas positions were traditionally determined relative to construction reference points, RTK allows recording as absolute coordinates, so the positional relationships among multiple distant manholes can be precisely understood. For sewer manholes, the cover elevation (top level) is also important. By applying a geoid height correction to the ellipsoidal height obtained from RTK positioning, you can compute the manhole cover elevation. This makes field survey data useful later when checking pipe slopes or performing flow simulations.

When surveying manholes with a smartphone-linked RTK system, it is easy to take a photo of the cover on site and associate it with the coordinates in the cloud. Photos are automatically tagged with high-precision latitude/longitude and orientation metadata, which is convenient for database searches and reference later. For numerous distributed manholes, centralizing location information and related materials (photos, notes) in this way will enhance the efficiency and sophistication of infrastructure maintenance.

Measurement of aboveground structures such as utility poles: RTK surveying is also powerful for aboveground assets like utility poles, streetlights, and signal poles. For example, while the installation positions of utility poles are generally fixed, the positional accuracy on older maps may be insufficient, and accurate current positions are required when planning road widening or undergrounding of utility lines. By holding a pole with an RTK receiver near the base of a utility pole, you can instantly record its installation coordinates. Even when measuring many poles in sequence, RTK speeds things up because you do not need to set up a heavy tripod for every point. Simply walking and holding the antenna up to acquire points one after another dramatically increases the number of locations a single person can survey in a day.

Another advantage of RTK surveying is the ability to digitally record photos and text notes together with position measurements. For example, photographing the management number plate on a utility pole ties that photo to the coordinate data for management purposes. Information that previously had to be written in a separate notebook can now be consolidated digitally in the field, reducing time spent organizing materials back at the office and preventing missing records. For field surveys covering many dispersed structures, this kind of digital surveying method especially contributes to improved efficiency.

Effects of introducing mobile RTK: improved efficiency, reduced manpower, increased safety

As described above, employing RTK surveying in utility sites yields various benefits. First is reduced manpower. With RTK enabling single-person surveys, tasks that previously required two to three people can be handled by one operator. Even sites without a resident skilled surveyor can have construction management engineers perform surveys themselves, giving greater flexibility in staffing and reducing labor costs. Second is reduced work time. Because RTK provides high-precision coordinates in real time, there is no need for long waiting times at each point; setup effort is minimal, and points can be acquired continuously while moving, so wide-area as-built measurements can be completed quickly. Data obtained in the field are immediately digitized, greatly reducing the need for post-processing and transcription at the office. Third is improved safety. Faster surveys shorten exposure time on busy roads and in deep excavations, reducing the risk of traffic accidents and falls. Fewer personnel on site also reduces contact opportunities, which is beneficial from an infection control perspective.

The introduction of RTK technology thus dramatically enhances the productivity and safety of surveying work and serves as a foundation supporting on-site digital transformation (DX). In utility construction in particular, because buried pipes and cables are difficult to alter once installed, reliably recording their positions contributes significant long-term value to infrastructure asset management. Moreover, 3D survey data obtained by RTK can be used to build construction models for CIM (Construction Information Modeling), supporting future BIM/CIM initiatives.

Conclusion: Simple surveying realized by LRTK

The usefulness of RTK surveying is clear, but some may find the barrier to deploying a full set of traditional equipment on site to be high. In this context, a smartphone-based solution called LRTK has emerged and is reshaping the RTK surveying world. LRTK is a next-generation surveying system composed of a palm-sized GNSS receiver, a mobile app, and cloud services. Using the dedicated receiver “LRTK Phone” that snaps onto iPhone or Android devices, and receiving network RTK (Ntrip) or satellite-based CLAS augmentation via the app, LRTK achieves centimeter-level positioning (half-inch-level positioning). From starting positioning to recording points, taking photos, and saving to the cloud, the entire workflow can be completed with a single smartphone—truly an all-purpose surveying tool usable by anyone on site.

With LRTK, as-built surveying of utilities that once required specialized equipment and manpower can be dramatically simplified. Because measurement can begin immediately with only a receiver and a smartphone, and because pricing is set to be approachable, deploying multiple units on a site is realistic. Using LRTK, post-laying surveying of pipes or inspections of structures on roads can be carried out in a one-person-one-device setup concurrently, eliminating bottlenecks even for large projects. Data are automatically uploaded to the cloud, so by the time workers return to the office, survey points that form the basis of as-built drawings and asset ledgers are already organized. Maintaining a 3D record per site that includes point-cloud data and photos can be practiced routinely without special burden—this is the major appeal of simple surveying with LRTK.

LRTK Cloud also enables unified management of points and photos, and data can be downloaded in CSV or SIMA formats for easy import into existing CAD drawings or GIS software. The LRTK series, packed with the latest technologies, is designed to be user-friendly even for non-specialist surveyors and realizes high-precision positioning with intuitive operation. For young engineers engaged in utility construction and infrastructure inspection, it is a powerful new tool to strengthen field capabilities. If you have issues recording the locations of pipes or manholes, consider introducing simple surveying with LRTK on your sites.

FAQ

Q: What is needed to start RTK surveying on site? A: Basically, a GNSS receiver that supports centimeter-level (half-inch-level) positioning and a communication environment for receiving correction information are required. If using network RTK, you need a smartphone or tablet with Internet access, a dedicated app, and a subscription to a correction data distribution service. With systems like LRTK, you can start positioning simply by attaching the dedicated receiver to your smartphone and launching the app.

Q: Can RTK surveying be done outside cellular coverage? A: Yes. Network RTK using GEONET requires a communication line, but LRTK receivers also support the QZSS Michibiki CLAS signal, so you can receive correction information directly from satellites and maintain centimeter-level positioning in mountainous areas or remote islands outside cellular coverage. Data collected offline are stored on the device and can be synced to the cloud later when you return to coverage.

Q: Can RTK surveying really achieve centimeter-level accuracy? A: Under suitable conditions, errors are typically within a few centimeters. In open-sky environments, horizontal accuracy of about 1-2 cm (0.4-0.8 in) and vertical accuracy of about 2-5 cm (0.8-2.0 in) have been confirmed. Accuracy depends on satellite reception conditions, so better results are obtained by measuring where there are no tall buildings or trees nearby and by remaining stationary while obtaining a fixed solution. Once a stable fixed solution is achieved, you can continue to record positions with high accuracy even while moving.

Q: Can non-specialist users operate the system? A: Yes. Modern RTK systems are very easy to operate, and basic point measurements can be performed without advanced knowledge. For example, LRTK allows you to tap the desired point on a smartphone map-style interface to record it. Detailed settings are automated, so beginners can become proficient in a short time. Because measurement, recording, and photo capture are integrated, even novices can efficiently and comprehensively document results.

Q: Isn’t the introduction cost high? A: Compared with traditional high-end surveying equipment, systems using a compact RTK receiver plus a smartphone app are much more affordable. Specific pricing for LRTK is available upon inquiry, but it is set to be comparable to the initial cost of a single general GPS surveying device. Even when purchasing multiple units, the budget required is lower than that for conventional equipment, making it a highly cost-effective solution.

Q: What smartphones are supported? A: Recent iOS (iPhone/iPad) and Android smartphones are supported. LRTK receivers work with devices that can physically attach the receiver and connect via Bluetooth or USB. Recommended environments include the latest-generation iPhone series and high-performance Android models.

Q: Is it easy to share survey data and integrate with other software? A: LRTK automatically saves positioning data to the cloud for real-time team sharing. From the cloud, point coordinates can be exported in CSV or SIMA formats, making it easy to import into existing CAD drawings or GIS software. Compared with managing paper ledgers, data storage and sharing are far more efficient and secure.

Dramatically improve field surveying accuracy and work efficiency with LRTK

The LRTK series delivers high-precision GNSS positioning for construction, civil engineering, and surveying, enabling shorter work times and major productivity gains. It supports the Ministry of Land, Infrastructure, Transport and Tourism’s i-Construction (ICT construction) initiatives and is an ideal solution for accelerating digitalization in the construction industry.

For more details about LRTK, see the links below.

• [What is LRTK｜LRTK Official Site](https://www.lrtk.lefixea.com/blog-js/mitibiki3)

• [LRTK Series｜Device List Page](https://www.lrtk.lefixea.com/)

For product inquiries, quotes, or consultation on introduction, please contact us via the [inquiry form](https://www.lrtk.lefixea.com/contactlrtk). Take your site to the next stage with LRTK.