Can RTK Replace a Total Station? Organizing the “Areas That Can Be Replaced”

Table of Contents

• What a total station is

• What RTK (GNSS surveying) is

• Differences between RTK surveying and total stations

• Areas where RTK can replace total stations

• Cases where RTK replacement is difficult

• Summary: The outlook for RTK and simple surveying with LRTK

• FAQ

Advances in surveying technologies such as total stations and RTK are substantially changing field surveying. In this article, we address the question, “Can RTK replace a total station?” by comparing the characteristics, advantages, and disadvantages of both, and by organizing the areas where RTK can be used to “replace” a total station. This is explained for those involved in surveying work (surveying firms, construction contractors, municipal staff, etc.) while also considering the latest trends. At the end of the article, we introduce a new simplified surveying solution using smartphones called LRTK.

What a total station is

A total station (TS) is an optical surveying instrument traditionally used in the field. It simultaneously measures horizontal and vertical angles and the distance to the target, enabling the determination of the three-dimensional coordinates of the target point. It integrates a transit (theodolite) and an electronic distance meter (EDM) and is indispensable across many fields such as construction, civil engineering, and land surveying.

When surveying with a total station, the instrument is normally mounted on a tripod at an instrument point, and angles and distances are measured relative to known control points. A prism reflector target is placed at the survey point, and the surveyor operates the total station to aim at the target. Such work typically requires two people: one operating the instrument and the other carrying and positioning the prism. Accurate surveying also requires pre-calibration and periodic instrument calibration, so maintenance consumes time and cost.

Total stations boast high accuracy and, when used appropriately, can achieve relative accuracies on the order of millimeters. They are especially powerful for precise alignment in confined areas such as setting out on building sites and erection works. However, they require a direct line of sight (no obstacles between the instrument and the prism), so measurements cannot be taken where the view is obstructed. For surveying large areas, it is necessary to reposition the instrument and remeasure from known points as appropriate, which means surveying wide areas can be time-consuming and labor-intensive.

What RTK (GNSS surveying) is

RTK stands for Real Time Kinematic, a high-precision positioning method using GNSS (Global Navigation Satellite Systems). In Japanese it is called “real-time kinematic positioning” or simply “RTK surveying.” GNSS includes multiple satellite positioning systems such as the U.S. GPS, Russia’s GLONASS, Europe’s Galileo, and Japan’s quasi-zenith satellite Michibiki (QZSS). RTK surveying uses signals from these satellites and data communication between a mobile receiver (rover) and a base station placed at a known position to correct positioning errors in real time.

Standalone GNSS positioning (code-based positioning) typically has errors on the order of several meters (about 5–10 m (16.4–32.8 ft)), but RTK’s relative positioning to a base station can reduce errors to a few centimeters. Typically, horizontal positions can achieve about ±1–2 cm (±0.4–0.8 in), and vertical accuracy about ±3 cm (±1.2 in). This level of accuracy is sufficient for applications that require centimeter-level accuracy (cm level accuracy (half-inch accuracy)), such as topographic mapping and staking out on construction sites.

RTK surveying normally requires a dedicated RTK-GNSS receiver (rover) and a base station that serves as the reference. Recently, it has become common to obtain correction information over the Internet from existing permanent GNSS station networks or commercial network RTK services (e.g., VRS = Virtual Reference Station) instead of setting up your own base station. The spread of these network-type RTK services means that in the field, a rover receiver and a communication terminal are often enough to immediately achieve high-precision positioning.

One advantage of RTK is that the coordinates obtained are from the outset absolute coordinates in a geodetic reference frame (latitude/longitude/height or plane rectangular coordinate systems). With a total station, you must align the instrument’s setup position to known coordinates or perform coordinate transformations later through survey computation, but RTK eliminates that labor. Also, GNSS positioning does not require a line of sight as long as satellite signals can be received, so RTK enables a single operator to efficiently survey wide areas.

Differences between RTK surveying and total stations

Let’s organize the concrete differences between RTK and total stations. Each has strengths and weaknesses.

• Necessary personnel and work efficiency: Total stations usually require two people, whereas RTK surveying can be performed by one person. Even when setting up a base station, one person carrying the rover receiver can visit survey points and complete the survey alone. For example, in one implementation, use of RTK led to on-site efficiencies described as “no line-of-sight required,” “about 10 seconds per point,” and “one person can do it.” When measuring many points across a wide site, RTK allows continuous recording of survey points while moving, so measurement speed can improve dramatically.

• Measurement environment: Total stations require a straight line of sight between the instrument and the prism and cannot be used when obstructed by trees or buildings. RTK, however, only needs to see the satellites, so it performs best in open outdoor environments. GNSS depends on sky visibility, so positioning is unstable or impossible in forests, urban canyons (areas surrounded by tall buildings), indoors, or tunnels. Therefore, RTK is powerful in open environments, whereas total stations remain useful where GPS signal availability is limited.

• Accuracy and characteristics: Both can provide high-precision positioning, but their natures differ. RTK provides absolute positional accuracy on the order of a few centimeters, whereas total stations offer very high relative accuracy in angles and distances and can achieve millimeter-level precision over short distances. For local high-precision tasks such as setting building axes or precise displacement monitoring, total stations are advantageous. However, the ability of RTK to obtain coordinates directly tied to a global datum gives it the advantage of producing results with absolute accuracy as well as relative accuracy between survey points.

• Survey range and effort: For extensive survey areas, RTK holds the advantage. RTK can position a rover several kilometers from a base station (network RTK can handle distances of several tens of kilometers), enabling seamless surveying over wide areas. Total stations are not suited to distance measurements of several hundred meters or more and require chaining survey lines and relocating the instrument to cover long distances. Also, total station work requires setting up and rotating the instrument for each instrument position, whereas RTK allows you to obtain many points simply by walking around without reestablishing the instrument at each point.

• Initial setup and installation: Total stations need setup, leveling, and orientation to a back sight (known point) before starting work. RTK also requires setup when using a base station, but when using a network service, even base station setup is unnecessary. Turning on a rover and waiting several tens of seconds for satellite acquisition and correction reception typically gets you ready to start positioning (initialization to a Fix solution also usually takes only tens of seconds). From a time-saving perspective, RTK simplifies field setup.

As shown above, RTK and total stations each have areas where they excel. In the next section we will look at specific situations in which RTK can actually replace total stations.

Areas where RTK can replace total stations

With the development of RTK surveying technology, many tasks traditionally performed using total stations can now be substituted by RTK. In particular, the following areas increasingly see RTK replacing the role of total stations.

• Wide-area topographic and control point surveying: RTK is powerful on open sites or mountainous surveying with good visibility. Tasks such as establishing multiple control points or measuring numerous terrain points for contouring can be carried out efficiently by one person with RTK. For example, in open-air environments such as airports, farmland, and large-scale development sites where there are no overhead obstructions, control point surveys and detailed surveys can be completed more quickly with RTK than with total stations. In one surveying company’s verification, network RTK was used for third-class control point surveys within an airport, achieving results equivalent to TS surveys while significantly reducing time.

• Construction site as-built management and surveying: Under the recent ICT construction (i-Construction) trend, mounting GNSS on heavy equipment to manage construction is becoming more common. Accordingly, RTK positioning is being used for checking embankment or base course heights and as-built management (measuring finished shapes). Tasks that formerly required setting out with a TS in advance or performing TS-based inspections at each stage are being replaced by GNSS-equipped machines and real-time RTK measurements. For example, in roller compaction tracking, GNSS records travel paths and compaction counts, reducing manual staking and observations. In these areas, RTK’s strength in providing wide-area, real-time positional information means it can often take over tasks previously done with total stations.

• Setting survey markers and staking out: RTK is also proving useful for staking out in building and civil engineering projects. With total stations, a surveyor and the staking crew needed to coordinate and maintain line of sight to stake out positions one by one. With RTK, simply carrying a pole-mounted receiver to the stake location allows instant coordinate confirmation. Dedicated GNSS-capable terminals or tablet apps can navigate the operator to target coordinates by indicating offset distance and direction, enabling people who are not surveying specialists to install stakes at prescribed positions. This makes staking and batter board setup partly replaceable by RTK equipment, reducing work time and personnel.

• Progress measurement and earthwork volume calculations: RTK is used for progress management in civil engineering (calculating excavated or filled earth volumes). While drone photogrammetry and ground LiDAR are also used, obtaining ground points directly with an RTK receiver is quick and reduces cost. Surveying the ground finely with RTK-capable equipment allows on-software volume calculations and cross-section creation from that data, replacing repeated cross-section surveys and calculations previously done with TS. Systems like LRTK that enable 3D point cloud scanning with a smartphone allow high-density point clouds to be obtained simply by walking the site and can automate volume calculations, dramatically improving efficiency in progress management.

• Rapid situational assessment at disaster sites: In disaster recovery, quick situational assessment and recording are required. Deploying survey teams to disaster sites and performing control and situational surveys with TS or GPS is changing with RTK adoption. For example, Fukui City quickly introduced an iPhone-based RTK surveying system (LRTK Phone) for disaster response and succeeded in speeding up on-site surveying and recovery work and reducing costs compared to conventional methods. Using portable RTK equipment allows one person to survey a disaster scene immediately after occurrence and share data instantly. In emergency initial surveys, RTK is a strong substitute for total stations.

In these areas, RTK is increasingly taking on the roles of total stations. Especially where “wide area, efficiency, and immediacy” are required, RTK’s advantages dominate.

Cases where RTK replacement is difficult

On the other hand, there remain cases where total stations are still superior or indispensable. It is important to understand situations where RTK is not万能 (not万能: not万能 untranslated?) — note: keep original meaning — where RTK cannot do everything.

• Places where satellite positioning is difficult: In forests, urban canyons, indoors, and underground spaces, GNSS satellite signals can be blocked or multipath errors increase, making RTK positioning difficult. In such environments, total stations that can sight and aim at prisms are relied upon. For example, forest surveys under dense canopy, displacement measurements inside underground tunnels, and interior building dimension measurements still require total stations or conventional instruments.

• High-precision deformation monitoring and precision measurement in confined areas: For cases like bridge or building monitoring where millimeter-level displacement detection is required, the high-precision angle and distance measurements of total stations, which are less affected by temperature and atmospheric effects, are suitable. Although RTK can be highly accurate, GNSS characteristics can cause slight positional fluctuations due to satellite geometry or tropospheric effects. For measurements that pursue precision to the limit (e.g., multi-year monitoring of dam displacements), total stations or EDMs are still used.

• Compliance with regulations and standards: Surveying work is subject to legal standards and regulations. In Japan, required accuracies and procedures are specified for each surveying method in public surveying and cadastral surveys. Network RTK surveying is officially recognized and spreading, but certain cases may require prescribed qualifications or installation of control points. Some administrative operations continue to operate based on traditional TS survey methods. When introducing RTK, it is necessary to confirm whether it conforms to required standards and institutional requirements.

Given these limitations, the practical approach is to use total stations where RTK is difficult and to use both technologies appropriately. In many sites, RTK is used as the main tool while TS is used as supplementary equipment, achieving a balance between efficiency and accuracy.

Summary: The outlook for RTK and simple surveying with LRTK

RTK surveying is becoming established as a technology that can replace much of conventional total station surveying thanks to its efficiency and ease of use. In particular, in the fields of wide-area surveying and construction management, there are increasing scenarios where “RTK is sufficient,” contributing significantly to improved survey productivity. At the same time, total stations remain indispensable under special conditions or where very high accuracy is required; their role has not completely ended. Going forward, both will continue to be selected according to site characteristics while leveraging each technology’s strengths.

Technological advances are making RTK even more accessible and easier to handle. For example, LRTK, developed by a startup from the Tokyo Institute of Technology, is a groundbreaking system that enables centimeter-class positioning by attaching a small RTK receiver to a smartphone (iPhone). High-precision surveying that once required specialized instruments can now be achieved with a pocket-sized device and a smartphone app. LRTK enables one person to perform staking and 3D point cloud scanning, and the acquired data can be shared to the cloud immediately for drawing and analysis. As in the Fukui City disaster response example, it is powerful for rapid on-site surveying.

With such new technologies, surveying will continue toward greater simplification and labor savings. The areas in which RTK can replace total stations are likely to expand, and more people including construction supervisors and municipal staff will be able to use high-precision positioning easily. If you feel “we’d like to use RTK at our company but it seems difficult,” considering smartphone-based solutions like LRTK may be an option. New surveying tools that break away from conventional assumptions are helping to improve on-site productivity and accelerate DX (digital transformation).

Finally, we have summarized frequently asked questions about RTK and total stations in a Q&A format.

FAQ

Q: What is needed to start RTK surveying? A: RTK surveying requires a GNSS receiver (rover) that supports centimeter-class accuracy and a base station that provides correction information. The base station can be provided by your own installation or by receiving correction data from an existing permanent GNSS station network via a network RTK service. Additionally, a controller to operate the receiver and display/record positioning results (a dedicated terminal, tablet, or smartphone) and a communication method (mobile network or radio) are needed. Recently, products combining smartphones and small receivers have appeared, making introduction easier than before.

Q: How accurate is RTK positioning? Is it sufficient compared to a total station? A: Under ideal conditions, RTK positioning can achieve about ±1–2 cm (±0.4–0.8 in) horizontally and about ±3 cm (±1.2 in) in elevation. This is generally sufficient for most surveying and construction applications. A total station can measure relative positions with millimeter-level accuracy over short distances. However, many field requirements only demand accuracy of a few centimeters, in which case RTK can handle the task. It is advisable to choose between RTK and TS according to the requirements.

Q: What should be done in places where RTK cannot be used, such as urban canyons or forests? A: In locations without sufficient sky visibility, RTK alone is difficult to use. In such cases, use total stations or EDMs as before, or employ a hybrid approach: obtain reference coordinates nearby with RTK and measure detailed points with a total station tied to those control points. For example, in forested areas, obtain control point coordinates with RTK in open spots, then use a total station tied to those control points to survey within the forest. Recently, smartphone RTK receivers that utilize enhancement signals from Japan’s Michibiki (CLAS) have appeared, enabling high-precision positioning even in some mountain areas with limited cellular coverage. Selecting the surveying method according to the environment is important.

Q: Will surveying costs decrease if RTK is introduced? A: In general, RTK use contributes to cost reduction by lowering labor and field time. Factors such as replacing two-person operations with one, shortening on-site time, and removing the need for additional control point installation improve efficiency. However, initial costs for RTK-capable equipment and software are required. Recently, inexpensive smartphone receivers and monthly network reference station services have lowered the initial investment barrier. Over the long term, many cases see total costs decline compared with traditional methods.

Q: Can people with little surveying experience handle RTK? A: Older RTK-GNSS equipment sometimes required specialized knowledge, but recent systems have improved user interfaces and are relatively intuitive. Especially with smartphone-app-linked products like LRTK, the design allows users to follow on-screen guidance to obtain survey results, enabling non-surveyors to perform basic staking and measurements. However, knowledge of coordinate systems and understanding of equipment characteristics are necessary to handle surveyed outputs correctly. It is advisable to receive training at introduction or to get expert support initially.

Q: Will RTK completely replace total stations in the future? A: It is possible that advances in RTK and other GNSS technologies will cover many areas currently handled by total stations. However, total stations possess optical surveying strengths, so coexistence and mutual complementarity are expected to continue for the time being. The important point is to choose the optimal method according to site conditions and required accuracy. Understanding the advantages of both RTK and total stations and acquiring the skill to use them appropriately will maximize surveying efficiency and accuracy. It is important to keep monitoring technological trends and use them suitably.