Traditional Methods vs. the Latest RTK:

A Comparison with Total Station Surveying

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Published March 4, 2025

What Is Total Station Surveying?
Total station (TS) surveying is a long-standing optical measurement method widely used in the field. A total station is an electronic-optical instrument that integrates a theodolite (for measuring horizontal and vertical angles) with an electronic distance meter (EDM) into a single unit, allowing high-precision measurement of both angles and distances simultaneously. When used in conjunction with surveying prisms (reflectors), it enables the calculation of three-dimensional coordinates between survey points.

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Equipment and Setup Procedure:
In total station surveying, the total station unit is mounted on a tripod. Required equipment includes, in addition to the total station itself, a reflector prism for the target point, the tripod, and a leveling device. First, position the total station over a known point or reference mark, and level it both horizontally and vertically using the bubble vial or electronic leveling feature. Then, determine the instrument’s current position (the coordinates of the setup point) using a method such as resection, completing the survey preparation.

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Surveying Procedure:
The surveyor sights the reflector prism target through the total station’s telescope. The instrument then automatically measures the horizontal angle, vertical angle, and slope distance to the target, and its onboard computer calculates the target’s three-dimensional coordinates from these data. This sequence is repeated at each survey point to collect the required coordinates. When there are many points or visibility is limited, the total station is relocated between measurements and repositioned over known points to extend the survey network.

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Accuracy:
Total stations boast extremely high precision. High‐end models achieve distance accuracy of approximately “±(2 mm + 2 ppm × distance),” which means that even at 500 m, errors remain on the order of ±3 mm. Angular measurements can be made in one‐arc-second increments (1/3600 of a degree), yielding an error of about 0.5 mm at 100 m. Such millimeter-level relative precision over short distances makes total stations ideal for tasks like laying out intricate structural components or measuring subtle displacements.

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Advantages:

• High Precision: As noted above, its short-range measurement accuracy is exceptionally high, making it ideal for precision surveying. In particular, when measuring elevations (height differences), combining it with leveling surveys can keep errors within a few millimeters.

• Stable Measurement: Less affected by weather (usable at night or under overcast skies) and capable of ranging to metallic targets. Since it employs optical distance measurement rather than radio waves, there’s no concern about radio‐frequency interference.

• Line‐of‐Sight Operation: Provided there is a clear line of sight, measurements are possible—even inside tunnels or in forested areas where direct satellite signals can’t reach. In urban settings, you can survey between buildings as long as the prism remains visible.

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Disadvantages:

• Labor and Time Intensive: The standard workflow requires two people—a total station operator and an assistant holding the prism—driving up personnel costs (though a robotic total station allows single‐person operation, it is expensive). Additionally, surveying large areas demands time for repositioning the tripod, and measuring each point is a slow, manual process.

• Line‐of‐Sight and Range Constraints: Measurements require a clear, unobstructed path between the instrument and the prism. If buildings or terrain block the sightline, you cannot measure directly and must either take a longer route or add extra survey points. There is also a maximum effective range, and measurement errors accumulate over greater distances.

• Equipment Operational Burden:
  Total station units are expensive and require regular calibration and maintenance. Furthermore, each setup demands skilled operation, so mastering its use can take considerable time.

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What Is RTK-GNSS Surveying?
RTK-GNSS surveying is a technique that enhances satellite positioning systems—such as GPS—to achieve high precision in real time. “RTK” stands for Real-Time Kinematic and employs two GNSS receivers: a base station and a rover. The base station is set up at a known coordinate location and transmits the error corrections derived from the satellite signals it receives to the rover. The rover then applies these corrections to realize centimeter-level positioning in real time.

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Mechanism and Technical Background of RTK Positioning:
In standard GNSS positioning, errors are on the order of several meters, but RTK can reduce them to a few centimeters. This is made possible by a technique called carrier‐phase measurement. By capturing the phase of the signals sent from GPS satellites and comparing the phase difference with a reference station in real time, the system calculates highly accurate relative positions. Since error sources—such as ionospheric delay and clock errors—affect both receivers similarly, the rover can correct its own measurements by subtracting the errors detected by the reference station.

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Survey Workflow:

1. Base Station Setup:
   If there is a known control point near the survey site, install an antenna and GNSS receiver at that location (if none is available, you may use data from public reference stations or electronic reference points). The base station computes real-time positioning errors based on its known coordinates and the satellite signals it receives.

2. Rover Setup:
   The surveyor mounts the rover’s GNSS antenna on a pole (or similar) and carries the handheld receiver/controller to the point to be measured. The rover then periodically receives correction data from the base station via radio link or over the Internet (e.g., using NTRIP).

3. Real-Time Correction and Point Measurement:
   At the rover, upon receiving correction data, it applies these corrections to its positioning solution to obtain high-precision current coordinates (known as the “FIX solution”). The surveyor then confirms the receiver has a FIX solution and records the point data. By repeating this at each point, you can acquire a real-time list of survey-point coordinates.

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Accuracy of RTK Surveying:
RTK-GNSS typically achieves about ±1–2 cm in horizontal position and ±2–3 cm in elevation (accuracy varies with distance to the base station and satellite geometry). For example, within a few kilometers of the base station, you can expect errors on the order of centimeters. However, if satellite signal reception degrades, the FIX solution may be lost and accuracy can drop, so total stations still hold an edge in millimeter-level stability. Nevertheless, the ability to perform absolute positioning over wide areas (even without pre-surveyed control points) and to measure many points in a short time are major benefits of RTK.

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Advantages:

• Work Efficiency and Labor Savings: RTK-GNSS enables one-person surveying. An operator carrying the rover simply walks to each point and presses a measurement button to capture coordinates, allowing rapid progress even over large areas. With no need to secure line of sight or reposition equipment, the number of points you can survey in a day far exceeds what’s possible with a total station.

• Wide‐Area Surveys and Immediate Results:
  Because it uses satellite positioning, RTK‐GNSS excels at long‐distance surveys. By measuring points several kilometers apart simultaneously, you can maintain high relative accuracy. The data are delivered in real time as coordinate values, allowing you to instantly verify results on site and compare them with your design coordinates.

• Easy Coordinate Integration:
  By placing the base station on a known point in a public coordinate system (such as WGS-84), surveyed points are automatically obtained as absolute coordinates in that system. This eliminates the need for post-processing to convert to a local grid, simplifying integration with GIS data and design drawings.

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Disadvantages:

• Dependence on Satellite Signals:
  A major drawback is that the survey environment heavily influences satellite reception. In areas with tall buildings or dense tree cover, satellites may be blocked or signals may reflect (multipath), preventing a FIX solution. In tunnels or indoors, positioning is generally not possible, requiring a fallback to optical methods such as total stations.

• Initial Implementation Cost:
  To conduct RTK surveying, you need at least two high-precision GNSS receivers (a base station and a rover). Dedicated units can cost several million yen each, meaning that the total system setup may be comparable to—or even exceed—the cost of a total station. However, in recent years, more affordable GNSS receivers and network-RTK services (which leverage existing reference stations) have become available, lowering the cost barrier.

• Operational Complexity:
  RTK surveying demands specialized GNSS expertise. You need to understand satellite constellations and the impact of ionospheric delays on accuracy, be familiar with base‐station data formats, and configure communication settings (such as radio frequencies and NTRIP parameters). Because a stable communication link is required at all times, in coverage‐dead zones like mountainous areas you must plan for additional radio equipment or consider switching to post‐processed positioning (PPK).

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Differences Between Total Station Surveying and RTK Surveying
Traditional total stations (optical surveying instruments) and RTK-GNSS systems (satellite-based surveying instruments) each have their own strengths and weaknesses. Below is a comparison of these two types of equipment in terms of accuracy, surveying time, personnel requirements, environmental adaptability, cost, and ease of operation.

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Accuracy: Total stations deliver millimeter‐level relative precision over short distances, making them ideal for fine dimensional work. In contrast, RTK‐GNSS surveying typically achieves about 1–2 cm accuracy horizontally, but its strength lies in covering large areas at once and providing absolute coordinates. Although its vertical accuracy doesn’t match that of a total station paired with leveling, it remains sufficient for most general civil engineering surveys.

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Surveying Time: With a total station, setup and resection consume time, and measuring multiple points requires moving the prism for each shot. RTK does require a base station setup, but once a FIX solution is obtained, points can be recorded instantly while on the move—dramatically reducing the time to complete a survey. This speed advantage is especially pronounced when surveying hundreds of points.

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Labor Costs: Total station surveying typically requires a team of two to three people—for ranging, recording, and holding the target—whereas RTK surveying can be carried out by a single operator, enabling significant manpower reduction. However, robotic total stations also permit one-person operation, so with sufficient equipment investment, the difference in staffing requirements can be offset.

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Environmental Adaptability: Total stations hold the advantage in urban or confined spaces. In densely built‐up cityscapes, tunnels, or forested areas, optical methods simply rely on maintaining line of sight, whereas RTK‐GNSS cannot acquire satellites and thus cannot operate. Conversely, on expansive sites or in disaster zones, RTK excels: it can survey without any ground control points and, even in mountainous terrain where ground visibility is limited, long‐distance measurements are immediately possible under an open sky.

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Cost: Both total stations and RTK‐GNSS receivers carry high price tags—new models often cost several million yen apiece. On the operational side, total stations incur periodic calibration fees and consumable costs (e.g., batteries), while RTK adds communication fees and, in some cases, subscription charges for correction services. Initial deployment costs vary by scenario, but when you factor in the labor‐savings RTK delivers, many find it more economical over the medium to long term.

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Ease of Operation: It’s hard to say definitively which is simpler to use. Total stations demand skill in setup and measurement, but their operating principles are intuitive and they tend to encounter fewer issues. RTK-GNSS requires initial configuration and management of signal conditions, but once you’re familiar with the workflow, setup is minimal and data processing is automated—making post-survey coordinate calculations virtually unnecessary. Both methods require proficiency, but overall RTK offers easier digital data integration and greater compatibility with ICT-based construction and BIM.

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Utilization and Implementation Benefits of LRTK
Among the latest RTK technologies, LRTK stands out. It evolves traditional RTK surveying by uniting high positioning accuracy with exceptional mobility. For example, LRTK receives dedicated correction data from satellites or proprietary networks, enabling real-time centimeter-level accuracy without deploying a base station. As a result, equipment preparation is simplified and initial setup time is greatly reduced—so you can power on the receiver on site and begin surveying immediately.

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Positioning Accuracy and Mobility of LRTK:
Leveraging the latest GNSS technology, LRTK consistently delivers accuracy on par with—or better than—conventional RTK (within a few centimeters). Moreover, because it can obtain correction data from a wide-area network, there’s no need to switch between base stations during large-scale surveys. Even in mountainous regions where base-station communication was once difficult, surveyors only need to bring an LRTK-compatible device to begin work. In other words, LRTK represents a leap from “RTK that requires you to carry a base station” to “RTK unbound by base stations.” This allows surveyors to carry all necessary equipment on their back, enter any site at a moment’s notice, and start measuring—and obtaining results—immediately.

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On-Site Implementation Examples:
Success stories have emerged from both construction sites and infrastructure maintenance. For instance, on a highway repair project, an LRTK-enabled GNSS receiver was used to measure pavement settlement across the surface in a matter of hours—completing a survey that traditionally took several days. In railway patrol inspections, crews equipped with LRTK devices detect track displacement in real time, enabling immediate repair decisions. Within the construction industry, a growing number of firms are adopting LRTK as part of ICT-driven construction, achieving labor-saving, real-time surveys that were previously difficult with total stations alone.

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As described above, LRTK incorporates the strengths of both RTK and total-station surveying to enhance on-site productivity. Its combination of high-precision and rapid surveying directly contributes to shorter project schedules and lower costs. Because a single operator can cover large areas, it also offers an effective remedy to labor shortages. The equipment’s compact, portable design makes it easy to handle even for teams new to RTK. In future infrastructure inspections and disaster-response operations, LRTK will continue to be a powerful, indispensable tool.