RTK in Road Construction: Alignments, Stations/Offsets, and Field Checks

Table of Contents

• Introduction: Surveying Challenges in Road Construction and the Move to ICT

• What Is RTK? High-Precision Technology for Road Surveying

• Alignments, Stations/Offsets: Basics of Road Alignment and Position Representation

• Traditional Stakeout Work and Its Challenges

• Practical Use of RTK for Alignment and Offset Stakeout and Efficiency Gains

• Streamlining Field Checks (As-Built Surveying) with RTK

• Benefits of RTK Adoption: Single-Person Surveying, Time Savings, and Improved Accuracy

• Notes on RTK Use (Environmental Conditions and Accuracy Control)

• Simple Surveying with LRTK: High-Precision Positioning Anyone Can Do

• Conclusion: How RTK Is Changing Survey Practices in Road Construction

• FAQ

Introduction: Surveying Challenges in Road Construction and the Move to ICT

In road construction, high accuracy and efficiency are required in surveying to place structures and perform work exactly as shown in the design drawings. Precise surveying is indispensable especially for laying out the road centerline (so-called alignment) and for accurately positioning details such as shoulders and curbs. Traditionally on site, experienced surveyors have used total stations and levels, working in multi-person teams to install batter boards (temporary references made from wooden stakes and horizontal boards) and confirm elevations while establishing reference lines and heights. However, in recent years, the construction industry has faced a chronic labor shortage, making it a major challenge to carry out the same surveying processes with limited personnel. Moreover, much precise surveying has relied on the intuition and experience of veteran technicians, leaving room for improvement in work efficiency and reproducibility (i.e., getting the same result regardless of who performs the survey).

Against this backdrop, the Ministry of Land, Infrastructure, Transport and Tourism has been promoting the introduction of ICT technologies on construction sites through policies such as *i-Construction*, aiming to improve productivity in construction. Specific measures include the use of 3D design data, the introduction of ICT-equipped construction machinery (machine guidance and machine control), and the deployment of high-precision positioning technologies on site. Among these, RTK positioning (Real Time Kinematic) using GNSS for centimeter-level positioning is attracting attention as a “game changer” that can transform site work practices, and it is becoming indispensable in surveying and construction control for roadworks. This article explains how RTK technology benefits alignment and station/offset surveying in road construction and how it affects field practice. We will compare it with traditional methods, discuss operational considerations, and examine the effects of RTK adoption. In the latter part of the article, we will also introduce LRTK, a modern simplified surveying solution, and look ahead to how RTK proliferation might reshape road construction surveying.

What Is RTK? High-Precision Technology for Road Surveying

RTK (Real Time Kinematic) is a technique that applies real-time correction information to satellite positioning (GNSS) to achieve centimeter-level positioning accuracy. Standalone positioning (single-receiver GPS) can result in position errors on the order of several meters due to satellite signal errors, but RTK obtains high-precision relative positions by receiving GNSS signals simultaneously at both a reference station (base) and the rover, and removing error factors common to both receivers (such as satellite ephemeris errors and ionospheric effects). In other words, by calculating the difference in real time between a “stationary receiver” and a “moving receiver,” the rover’s position can be narrowed down to a few centimeters of error. Because correction computations are performed continuously on site, results are obtained immediately, allowing position checks and surveying decisions to be made on the spot without waiting for post-processing.

In Japan, the infrastructure supporting high-precision positioning is well developed. The spread of network RTK services (such as Ntrip distribution) that use the Geospatial Information Authority of Japan’s reference network (GEONET) makes it possible to obtain correction information via the Internet and achieve centimeter accuracy without setting up your own base station. Also, receivers that support the Quasi-Zenith Satellite System “Michibiki” centimeter-level augmentation service (CLAS) can directly receive high-precision correction data from satellites even in mountainous areas without cellular coverage. With these technical foundations in place, RTK surveying is now in practical use at construction sites across Japan. In roadworks, RTK is increasingly being considered and adopted for various processes, from machine control for subgrade grading to as-built measurement and inspection of structures. For typical civil engineering tasks requiring position accuracy on the order of ±1–2 cm (±0.4–0.8 in), RTK is generally sufficient, and automated construction using GNSS-equipped machines (machine guidance/machine control) has already been introduced at many sites. RTK is also proving effective for layout tasks such as stake driving, where the machine can be guided to the design coordinates of stake centers. In short, RTK has made it possible to perform precision surveying tasks that formerly required multiple personnel and long hours, much more quickly by a single operator. High-precision baseline layout and as-built confirmation, once difficult, have seen dramatic efficiency gains, and construction management practices are changing. However, as discussed later, RTK is not omnipotent: satellite signal reception conditions and operator technique can affect accuracy, so careful operation is necessary.

Alignments, Stations/Offsets: Basics of Road Alignment and Position Representation

Common foundational terms in road construction surveying include “alignment,” “station,” “offset,” and “alignment” (Alignment). Alignment refers to the path along the road centerline — that is, the route shape of the road. It consists of the horizontal route (plan alignment) and the longitudinal gradient (vertical alignment), and is represented by combinations of straight lines and curves (horizontal and vertical curves). It is the reference line defined in the design drawings that must be accurately reproduced on site; the road width and the placement of structures are determined relative to this line. Accurately laying out the alignment is fundamental to constructing the road in the planned location and orientation. Also referred to as “Alignment,” it is increasingly provided as 3D data formats such as LandXML.

A station indicates a position on the road by distance. In Japanese it is called “sokuten kyori” or “kilometre post,” and is managed as the cumulative distance from a starting point. Often shown on drawings in formats such as “0+000” or “1+200” (for example, 1+200 means the point 1,200 m (3,937.0 ft) from the starting point), stations specify arbitrary points on the road (such as intersections, curve start/end points, and locations for structures). Drawings may also use STA or KP. An offset is the lateral distance from the reference centerline (alignment). During design, offsets indicate how far from the centerline objects are placed to the left or right. For example, “right offset 5.00 m (16.40 ft)” means a point 5.00 m (16.40 ft) to the right of the centerline. On site, it is common to combine stations and offsets to express positions such as “at station X+XXX, Y meters to the right,” and to specify particular points in this way. Road width, shoulder/gutter positions, and the placement of signals, signs, and retaining walls are all managed using station/offset.

What matters in field surveying is reproducing the design alignment (or provided coordinate values) on site accurately based on the station and offset values shown in the design. In other words, drawing the correct reference line (centerline) and placing structures at the positions corresponding to the stations along that line per the drawings is the essence of construction accuracy.

Traditional Stakeout Work and Its Challenges

Before RTK, baseline layout (stakeout) and position layout in road construction were done manually using total stations (optical survey instruments) and staffs. One typical procedure was to connect known points along the design centerline on site and install temporary reference stakes called batter boards at regular intervals. Batter boards are wooden stakes with horizontal boards (string lines) attached to indicate height and position references on site. Survey crews typically work in teams of two or more: one person operates the total station to measure angles and distances while another drives stakes or marks the indicated location, gradually marking the centerline and roadway width on the ground per the design. For example, the team might measure the distance to a given station with a tape or electronic distance meter, drive a stake at that point to mark the center point of the road, then measure a perpendicular offset from that stake by tape to set another stake at the offset position to indicate the shoulder or structure location.

However, the traditional method has several challenges.

• Labor and time intensity. Operating the survey instrument and driving stakes requires at least two people, and on long road sections many stakes must be installed sequentially over a wide work area. Each survey point takes time to set, and in large projects, laying out hundreds of points could take several days. One report noted that stake position surveying using the conventional method took about six times longer than modern digital methods, indicating that the old approach hindered productivity improvements.

• Dependence on the know-how of experienced technicians. Precise operation of total stations, skill in stably installing batter boards, and the knack for adjusting errors when staking out points often relied on veteran surveyors’ experience, causing variability in efficiency and accuracy depending on the personnel. It is difficult for inexperienced teams to work alone, and a shortage of skilled staff can become a bottleneck in site progress.

• Lack of real-time verification and limited data utilization. With conventional methods, the driven stakes and marks on site were the only references, and it was difficult to numerically verify on the spot whether they were correctly placed. To confirm whether measured points matched the design, one often had to return to the office to check against plans or perform additional verification surveys later, making immediate error detection and correction difficult. Survey data tended to remain in paper notebooks or as marks on plans, making digital data utilization less likely.

Thus, traditional stakeout work was labor-intensive and relied on artisanal skill for accuracy. There were also safety issues: survey staff walking back and forth on roads for long periods faced higher risks of vehicle contact, and the physical burden of working in extreme heat or cold was nontrivial. RTK-based surveying approaches, discussed next, emerged to address these challenges.

Practical Use of RTK for Alignment and Offset Stakeout and Efficiency Gains

Introducing RTK positioning into surveying operations dramatically changes how baseline lines and point layout are performed in roadworks. The greatest feature is that a single worker can directly mark design positions on site. Tasks that formerly required multiple people for centerline and stake measurement can now be done by one person carrying an RTK receiver (rover).

A typical workflow is to prepare an RTK-capable GNSS receiver and initialize the device’s positioning reference (coordinate system) based on known points on site or the public coordinate system. Many Japanese projects use the Geospatial Information Authority of Japan’s plane rectangular coordinate system (such as JGD2011) for design drawings, so the RTK receiver should be set to the same geodetic and coordinate system. When using network RTK, enter Ntrip account information to receive correction data (base station data) over the Internet (if setting up your own base station, place an antenna on a known point, set it to base mode, and transmit correction data to the rover by radio or Internet). Once positioning preparation is complete, the rover is taken to the area to be surveyed and measurements begin.

To stake out points along the road centerline, prepare a list of station coordinates along the centerline from the design in advance. Nowadays, centerline coordinates can often be directly extracted from 3D design data, making it easy to prepare a CSV file of major point coordinates (X, Y) or to input them into a surveying app beforehand. When the rover or a connected tablet displays the target station coordinates, it shows the distance and direction to that point in real time. The operator walks to the indicated location following the screen guidance and marks the ground with a stake or spray paint when the point is reached. In this way, the operator can lay out major points along the centerline (e.g., intersection points of straight and curve segments, curve start/end points, and regular interval survey points) one after another alone. Traditionally, technicians measured distances by tape and walked back and forth to sequentially set points, but RTK provides centimeter-level current location awareness, so points can be set in any order without introducing error. For example, a worker could first go 500 m (1,640.4 ft) ahead to mark the next intersection point (IP) and then return to mark intermediate points; RTK will still place those points accurately.

Offset stakeout (measuring lateral distances) is also greatly improved with RTK. If the offset distance from the centerline to a specified object is known, the operator first positions on the centerline at the relevant station and then simply moves laterally by the indicated distance to find the offset point. Advanced RTK surveying apps and devices offer an “offset stakeout” function that applies a preset offset value and navigates to the point. For example, specifying “station 100+00, right offset 5.00 m (16.40 ft)” lets the device automatically compute the coordinates and guide the user to the designated point via on-screen prompts or voice guidance. Even if the device in use lacks built-in offset calculations, you can compute offset point coordinates from the design data and use RTK to navigate to them as you would for centerline points. This enables efficient stakeout of shoulder lines, ends of median strips, retaining wall foundation points, and other points at specified lateral distances from the centerline. Traditionally, an offset was established by stringing line on batter boards along the centerline and measuring perpendicular distances with tapes; RTK eliminates that effort. Additionally, when multiple areas need to be worked in parallel, several operators with rovers can independently lay out points, adding flexibility to project scheduling.

Thus, RTK-based baseline and offset stakeout enables high-precision layout work with far fewer people and shorter work times than conventional methods.

Streamlining Field Checks (As-Built Surveying) with RTK

RTK also dramatically streamlines the measurement and verification of as-built conditions after construction (as-built surveying and inspection). Previously, surveying after completion was performed separately and compared with design drawings to check deviations, but with RTK you can take survey points directly on the finished pavement or structures and immediately obtain accurate coordinates in the public coordinate system (or corresponding station/offset values). Comparing these values with the design on-site allows immediate identification of as-built errors. For example, measuring the pavement surface elevation with RTK and comparing it to the design vertical profile can instantly indicate “X cm higher/lower than design.” In other words, inspection surveying and stakeout can be carried out sequentially on the same device. With a single RTK terminal, you can instantly check discrepancies between design and measurement on site and make rapid decisions about rework or additional work. Being able to judge as-built acceptability in real time during construction greatly reduces rework and waste.

Because RTK allows consistent methods from alignment layout to as-built checking, it makes construction control far more efficient and precise compared with conventional approaches.

Benefits of RTK Adoption: Single-Person Surveying, Time Savings, and Improved Accuracy

• Single-person execution of surveying tasks becomes possible. Tasks that previously required teams of two or more for centerline surveying and stakeout can be performed by one person. A worker with a high-precision GNSS receiver can move around the site to set points, eliminating the need to allocate personnel across large earthwork sites. In civil sites suffering from chronic labor shortages, this allows surveying and batter board work to be handled with fewer people. In road construction, securing personnel solely for surveying was often a bottleneck; enabling one person to handle wide-area surveying has significant impact. This is also an effective solution to the construction industry’s broader issues of technician shortages and aging.

• Significant reduction in work time. RTK provides real-time observations, so long observation times per point are unnecessary. Unlike total station work, which requires instrument setup, angle settings, backsight/foresight procedures, and moving the instrument point after a certain number of measurements, RTK allows continuous measurement while moving, avoiding such rework. You can verify and measure points on the go without waiting, so overall the time required to set the same number of points is drastically reduced. Surveying processes that often constrained the project schedule are sped up, giving subsequent construction tasks more leeway and improving productivity.

• Improved surveying accuracy and quality. RTK delivers benefits in accuracy control and quality assurance. Subtle adjustments that once relied on veteran intuition can be standardized using RTK numeric outputs, making it easier for anyone to achieve the same results. Always working from centimeter-level coordinate data reduces variability and human error, stabilizing overall quality. Collected data can be recorded and shared digitally, enabling later verification and comparison with design values, simplifying quality control. In other words, consistent accuracy is maintained regardless of the operator, enhancing reproducibility of field surveying. Reducing variability arising from surveyor experience improves construction management reliability and helps standardize as-built quality.

Notes on RTK Use (Environmental Conditions and Accuracy Control)

RTK is extremely useful, but to maximize its performance several operational considerations must be observed. First is satellite reception environment. RTK requires simultaneous reception from many GNSS satellites, so accuracy is more stable the more open the sky is. Forested areas or urban environments with tall buildings can obstruct sky view and reduce the number of usable satellites, making it difficult to obtain or maintain a fixed solution (centimeter-level solution). Where possible, choose observation locations with a clear overhead view; if there are unavoidable obstructions, schedule observations when satellite geometry (constellation) is favorable. Environments like under elevated bridges or in deep valleys where direct satellite visibility is not available may render RTK unusable.

Next, be careful about signal reflection and interference. Nearby metal fences, construction machines, or building facades can reflect satellite signals and cause multipath errors, which distort positions. Avoid such problematic radio environments when possible, and if obstacles are unavoidable, keep adequate distance between the receiver and the reflecting object during measurement.

The distance from the base station also affects accuracy. When using a local RTK base station, place it on a known point as close to the work area as possible to minimize distance to the rover. For network RTK, use regional reference services such as VRS (Virtual Reference Station) based on nearby reference stations so that correction information is applicable to the site. The greater the distance to the base, the larger differential ionospheric and tropospheric effects become, which can degrade accuracy and destabilize the solution.

Furthermore, proper handling and verification of equipment are essential. Keep the antenna as vertical as possible during observations and avoid measuring with a tilted pole (even if the receiver has tilt compensation, extreme tilt should be avoided). Perform check measurements at known points before and after surveys to verify that the instrument is showing correct values. Beware of mistakes in setting antenna heights or reference elevations; it is reassuring to run a quick function test in an open, level area before going to the field. RTK is high-precision but delicate, so thoroughly following the basics — “choose the right environment, handle equipment correctly, and verify accuracy” — lets you extract the technology’s full performance.

Simple Surveying with LRTK: High-Precision Positioning Anyone Can Do

A prominent solution that further accelerates RTK adoption is LRTK. Developed by a startup from the Tokyo Institute of Technology, LRTK is a system composed of a compact RTK-GNSS receiver and a dedicated cloud service. By attaching this device to a smartphone or tablet and connecting it with a dedicated app, anyone can perform centimeter-level positioning easily — a “smartphone surveying” approach.

Traditionally, RTK surveying used large bench-top receivers on tripods or long poles with antennas, but the LRTK receiver is ultra-compact and lightweight — about 13 mm thick and weighing only about 125 g — a pocket-sized surveying instrument. Powered by an internal battery, it does not require cumbersome power cables on site; carrying only the receiver and a smartphone enables positioning anywhere. Operation is simple: attach the receiver to the phone, turn it on, and pair via Bluetooth. GNSS observation data are streamed in real time to the smartphone app, providing high-precision position results on the spot. The app’s buttons handle everything from point measurement and recording to various data processing tasks. With just one small receiver and a smartphone, you can obtain coordinates, be guided to stakeout positions, tag photos with positioning data, perform 3D scan surveying, and even run AR simulations — an all-in-one platform.

For example, when taking site photos with the smartphone camera while LRTK is measuring, high-precision geotags are automatically added to the photos and saved to the cloud immediately. The app also provides stakeout guidance: selecting any point from the design on the app triggers audio guidance and on-screen directions to lead you to that coordinate for stake driving. This enables finding points on the centerline with confidence as long as the design data are accessible on the phone. Optional features may include LiDAR scanning with the phone or photogrammetric point cloud generation. Point clouds acquired in the field can be georeferenced in real time by RTK, enabling creation of 3D as-built models while surveying. Of course, collected data syncs to the cloud immediately, allowing on-the-spot calculations of distances, areas, and volumes and comparison against design models for error analysis. Tasks that previously required separate devices and procedures can be completed within the LRTK system.

Crucially, LRTK offers positioning accuracy comparable to conventional bench-top GNSS equipment. In open-sky conditions, horizontal errors are generally around 2–3 cm (0.8–1.2 in) and vertical errors around 3–4 cm (1.2–1.6 in); in urban or forested conditions, errors are typically in the range of several centimeters to a dozen or so centimeters. LRTK supports network RTK and Michibiki CLAS, so with adequate communications you can achieve horizontal ±1–2 cm (±0.4–0.8 in) and vertical ±3–4 cm (±1.2–1.6 in) positioning using just a smartphone. This level of accuracy removes the need for fine adjustments on batter boards or alignment using string lines. LRTK can output coordinates directly in the public geodetic system used in design drawings, so points on the design correspond directly to measured points without intermediate transcription processes, reducing simple copy errors and improving efficiency and accuracy.

Operationally, LRTK is revolutionary. Its intuitive smartphone app makes it easy for anyone to use, allowing less experienced workers to perform surveys and stakeouts by following app instructions. This contributes to skill leveling on site: even without a resident veteran surveyor, modern technology can cover many needs. LRTK’s lower cost compared to traditional dedicated surveying equipment also encourages adoption as a “one-per-person” high-precision positioning tool. Field supervisors and crews have praised LRTK’s convenience and utility, and it is quietly becoming popular. Its ultra-lightweight design reduces equipment transport burden and lessens fatigue during long outdoor work — a safety plus. Cloud integration simplifies reporting to the office, improving communication between field and office.

In summary, LRTK is a next-generation tool designed to let “anyone, immediately, accurately” perform surveying and measurement. It maximizes RTK benefits while dramatically lowering operational barriers. Tasks that once required expensive equipment and skilled technicians can now be done with a small device and a smartphone, which is highly significant for improving construction productivity. LRTK supports the Ministry’s i-Construction initiatives and is an excellent product for advancing digitalization on construction sites. In the future, palm-sized surveying devices like LRTK may become standard equipment on site, with each worker using their smartphone to perform surveying, as-built checks, and stakeout. Site management that once depended entirely on specialized surveying teams is changing: a future in which “surveying is not a special task but part of routine work” is approaching.

Conclusion: How RTK Is Changing Survey Practices in Road Construction

This article detailed RTK surveying practices and their effects on alignment and station/offset work in road construction. In summary, RTK has dramatically improved the efficiency and sophistication of surveying on road construction sites. Tasks that previously required teams and long hours for centerline layout and stakeout can now be done quickly by a single person, and RTK is becoming central to many civil surveying and construction tasks. Centimeter-level positioning is sufficient for a broad range of layout and as-built measurement tasks, and GNSS machine control for subgrade grading and earthwork quantity management is already in use, demonstrating RTK’s practical benefits.

That said, RTK cannot completely replace traditional methods in every situation: optical surveying still has a role in highly specialized tasks requiring millimeter precision, such as setting bridge bearings. However, for common road alignment management and as-built checks where centimeter-level error is acceptable, RTK is becoming the standard choice. The key is to determine the required accuracy for each situation and apply the appropriate method. Use RTK aggressively where it meets requirements, and complement it with optical instruments where needed.

By leveraging RTK, you can reduce surveying man-hours and personnel while improving quality control through digital data. Site supervisors should first assess whether RTK is suitable for their site (in terms of required accuracy and radio environment) and introduce it where feasible. With personal-use tools like LRTK emerging, RTK is no longer an exotic cutting-edge technology but an accessible tool for everyone. Road construction surveying is at a turning point, and adopting RTK-based digital surveying methods enables new, unconstrained approaches to construction management. Try it on your site and experience the benefits.

FAQ

Q1: Can RTK positioning completely replace traditional surveying instruments like total stations and levels? A1: At present, complete replacement is difficult, but RTK is becoming the primary method in many cases. For wide-area centerline layout and as-built measurement where centimeter-level accuracy is sufficient, RTK can largely substitute. However, tasks requiring millimeter-level precision, such as aligning bridge bearing positions or machine installation centerlines, still require total stations and optical precision measurement. In practice, hybrid operation — using RTK for initial layout and optical instruments for the final millimeter adjustments — is increasingly common. It is realistic to use each tool according to its strengths and complement them as needed.

Q2: What factors affect RTK accuracy, and how can high positioning accuracy be maintained on site? A2: Major factors include satellite reception environment (how open the sky is and whether there are obstructions), distance to the reference station, atmospheric conditions (ionosphere and troposphere effects), and equipment handling (antenna tilt and setup errors). To maintain accuracy, choose locations with a clear sky view to capture more satellites and obtain a stable fixed solution. Avoid observations near tall buildings or metal fences that cause reflection and interference, and keep as much distance as possible from such obstacles. When using a base station, place it close to the work area; for network RTK, use regional VRS services so correction data reflect local conditions. Keep the antenna pole vertical during observations and perform check measurements at known points to confirm there is no instrument drift. In short, “choose the environment, handle equipment correctly, and verify” is the key to getting RTK’s full accuracy.

Q3: What is LRTK, and how does it differ from traditional RTK equipment or other GNSS receivers? A3: LRTK is a compact RTK-GNSS receiver and surveying app system designed to work with smartphones. Unlike traditional RTK equipment, which required dedicated controllers and bench-top antennas, LRTK simply attaches a small receiver to a smartphone to achieve centimeter-level positioning. The biggest differences are its portability and ease of use: the receiver is lightweight and pocket-sized, and the smartphone app offers an intuitive UI with functions like coordinate guidance, AR display, and cloud integration. While conventional equipment was primarily for positioning, LRTK is an integrated platform that combines photo capture, point cloud measurement, stakeout guidance, and more. It is also less expensive, making it more accessible for widespread adoption. In short, LRTK keeps RTK accuracy while greatly improving usability and versatility.

Q4: Can RTK be used in forests or indoors? How can positioning be done where satellites cannot be seen? A4: In dense forests, usage becomes more difficult, but partial positioning may be possible depending on conditions. If the sky is heavily obscured by trees, the number of receivable satellites decreases and it may be hard to maintain a fixed solution. Modern GNSS receivers support multiple frequencies and satellite systems, improving performance so that some positioning may still be possible in leafed areas, but accuracy tends to degrade and errors of tens of centimeters or more may occur. In fully indoor environments (inside buildings or tunnels), RTK is generally unusable because satellite signals are blocked; other methods such as optical distance measurement (total station) or local indoor positioning systems are needed. In semi-outdoor spaces like under bridges or in the shadow of buildings, if you can secure an overhead sky view of about 30–40 degrees it may be possible to temporarily maintain enough satellite visibility and augmented signals for a fixed solution. Fundamentally, whether the sky is visible determines RTK viability. In forests, seek openings; under canopies, extend measurements from outdoor reference points as needed.

Q5: How reliable is RTK vertical (height) accuracy? Will levels (precise leveling) become unnecessary? A5: RTK vertical accuracy is somewhat worse than horizontal but is practically within a few centimeters. Under good conditions, about 3 cm (1.2 in) vertical accuracy can be expected. However, precise leveling can measure height differences to the millimeter level, so it remains valuable for applications requiring very high vertical accuracy. For typical civil engineering work, RTK is usually adequate for transferring reference elevations and checking as-built heights. RTK-GNSS is increasingly used where elevation control is important, such as in embankment thickness management. Nevertheless, for long-distance longitudinal leveling or monitoring settlement and other measurements requiring high stability and rigor, precise leveling is still the standard. Therefore, RTK does not immediately render leveling obsolete; instead, use both appropriate to the task. It is practical to establish key elevation benchmarks by leveling and then use RTK for everyday elevation checks to improve confidence in RTK vertical values.

Q6: What is needed to start RTK surveying, and what preparations are required for field use? A6: Essentially you need an RTK-capable GNSS receiver (rover), a base station or correction service, a communication method linking them, and a controller terminal (dedicated controller or tablet/smart device) to display and operate positioning. If you set up your own base station, place an antenna on a known point near the site, ensure power and communications, and transmit correction data to the rover via radio or a SIM/Internet connection. If using a private or public network RTK service, equip the rover with an Internet-capable SIM and configure the service ID and password to receive corrections. On site, the procedure is typically: place the base station antenna on a known point (if applicable) → start the rover → set coordinate system and antenna height → establish communication. For network use, connect the rover to Ntrip to begin receiving corrections. Once a fixed solution is obtained, check measurements at known points to confirm accuracy. Initial setup and connection may be confusing, but with experience you can start positioning quickly. It’s wise to test operations in an open, flat area beforehand. With practice, you can have the base station up and running in the morning and start work with the rover shortly thereafter.