1. Traditional Methods in Civil-Engineering Surveying and Their Issues

Basics of Traverse Surveying (workflow, equipment, accuracy)

One of the oldest techniques in civil surveying is traverse surveying. Starting from a known control point, the surveyor establishes a network of reference points by connecting a sequence of stations one after another.In practice, the surveyor first sets a transit or total station over a point with known coordinates, erects prisms (staff targets) on a backsight and a foresight, and measures the horizontal angles and distances. Repeating this process adds new stations, and the traverse is finally closed on the start point or another control point, forming the control network. Required equipment includes a total station (integrating a theodolite and EDM), prisms, tripods, staffs, and field notebooks. After observing the angles and distances between successive stations, the coordinates of each point are computed and a closure adjustment is applied to obtain the final coordinates. When carried out correctly, millimetre-level accuracy is attainable; however, errors accumulate with traverse length, so periodic ties to known points and rigorous closure adjustments are essential.

Traverse surveying can achieve reliable accuracy when performed correctly, but the workflow is both labor-intensive and time-consuming. A crew of at least two skilled surveyors is required: one operates the total station while the other stands at each successive point holding the prism. On rugged or obstructed sites, securing clear sight lines is difficult, so additional points or detours must often be planned, demanding flexibility. Because the method depends heavily on manual effort, time and manpower requirements grow rapidly as the survey area expands.

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Limits of Surveying with Total Stations (workload · time · staffing)
A total station (TS) greatly streamlines fieldwork by measuring angles and distances simultaneously—far more efficient than the old transit-plus-tape routine. Even so, “conventional” TS surveying still faces several constraints.First, the physical workload is high: the instrument must be re-set for every shot, and on large sites crews lug the tripod from point to point countless times. Second, the observation range is restricted to the instrument’s line of sight, so obstacles or steep terrain often force time-consuming re-measurements. Third, from a manpower standpoint the job usually needs a two-person crew (even robotic total stations have limits on solo use), and coordinating operator and rod-person adds communication overhead. On topographic surveys or as-built checks with many points, measuring each location one by one with a total station inevitably takes considerable time, so project progress can be constrained by the pace of the surveying team.

Moreover, on active construction sites, vibration and noise can restrict total-station work. For instance, vibrations from excavators or dump trucks may destabilize readings; traditionally, crews would halt nearby machine operations for safety while measurements were taken. In effect, surveying had to be separated from other site activities, becoming a bottleneck to overall efficiency.

These challenges have fuelled demand in civil surveying for a method that delivers high-precision positioning faster and with fewer personnel than traditional total-station workflows.

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2. The Rise of RTK Positioning and Its Benefits

What is RTK? (How it differs from standard GPS)

RTK positioning—short for Real-Time Kinematic—is a satellite-based technique that delivers centimetre-level accuracy in real time. Conventional stand-alone GPS (single-receiver GNSS) calculates its position with just one receiver, so orbit errors, atmospheric delays, and other factors typically leave several metres of error. RTK overcomes these limitations.

In RTK positioning, both a base station—a receiver at a point whose coordinates are already known—and a rover—the receiver at the point you want to measure—observe GNSS signals simultaneously. The base transmits real-time correction data (the differences between its known position and what the satellites report) to the rover, which applies those corrections on the fly. This cancels most of the errors unavoidable in stand-alone GPS and raises practical accuracy to about 2–3 cm.

Because the base station’s position is precisely determined in advance, the rover can compute its own coordinates in real time by measuring its high-precision baseline distance from the base.

RTK can draw on multiple satellite constellations—not only the U.S. GPS system but also Japan’s QZSS (“Michibiki”), Russia’s GLONASS, and others. Because the rover receives live correction data while it measures, it delivers a level of accuracy far beyond stand-alone positioning.
Be aware, however, that accuracy drops if the radio link from the base or the satellite-signal environment deteriorates; the solution can become ambiguous and slide back to ordinary GPS-level errors. Under good conditions the difference between RTK and conventional GPS is striking—RTK truly represents a “revolution” in positioning precision.

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Challenges Solved by Adopting RTK

Introducing RTK positioning addresses many of the issues inherent in traditional surveying. The most significant benefit is a dramatic boost in work efficiency. An RTK rover is portable and can be operated by a single person, turning what used to be a two-person task into a solo workflow. Because line-of-sight is no longer required, any spot with a clear view of the sky—and thus satellite reception—can serve as a survey point.

For example, sites in mountain valleys or dense urban areas, where setting up sight lines for conventional instruments was difficult, can now be surveyed without worrying about obstacles. In short, RTK enables one surveyor to work quickly and with centimetre-level accuracy, even where clear sight lines are impossible, greatly reducing field time and increasing overall productivity.

Because RTK delivers positions in real time, you no longer have to pause after each observation to run calculations or check drawings—the result appears instantly, and you can move straight on to the next point. Large numbers of points can thus be measured in rapid succession, dramatically increasing efficiency over total-station workflows and slashing labor requirements for topographic surveys and as-built checks.

From an accuracy standpoint, RTK achieves millimetre- to centimetre-level precision through differential positioning relative to the base. Horizontal accuracy remains virtually constant—about 2–3 cm—within a radius of roughly 10–15 km of the base. Vertical error is typically about twice the horizontal error, so strict height control still requires attention, yet the precision is more than adequate for ordinary site-level elevation work.

Because RTK coordinates are referenced directly to a global geodetic datum, there is no need to establish a local site grid; harmonising data across multiple sites or with existing drawings becomes easier, widening the scope for re-using and integrating survey data.

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Efficiency Gains from Switching to RTK

Here are the main ways productivity improves when you move from total-station surveying to RTK positioning.The biggest advantage—worth repeating—is the dramatic savings in both manpower and time. A control-point survey that used to require a two- or three-person crew can now be completed by a single operator with RTK. Eliminating the need for an assistant not only reduces labor but also removes the necessity for shouting instructions in noisy environments, thereby improving both safety and comfort on site.

Another key efficiency gain is the ease of running surveying in parallel with other operations. Because RTK allows points to be observed even while heavy machinery is in motion, surveying and construction can proceed simultaneously instead of being separated. This parallel workflow helps shorten the overall project schedule.

Moreover, RTK provides positioning results in real time, so the data can be used immediately. Coordinates measured with the rover can be displayed on a tablet on the spot, checked against design drawings, and—if needed—new points can be surveyed right then and there. Tasks that once required returning to the office for calculations and plotting with a total station can now often be completed entirely in the field. Faster feedback from surveying to design and construction accelerates the entire PDCA cycle.

Finally, RTK greatly expands the practical survey area. A total station limits you to locations where the instrument can be set up, but RTK-GNSS can cover vast sites with far fewer “blind” zones. On a large, undulating earth-work project, for instance, a traditional survey would require intermediate stations and constant plan adjustments; with RTK you can simply “draw a single stroke,” walking the whole area and recording points continuously. In this way, switching to RTK dramatically boosts the productivity and flexibility of surveying itself—and ultimately streamlines the entire civil-construction workflow.

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Comparing Total-Station and RTK Surveying

RTK offers clear advantages over traditional total-station (TS) methods: fewer crew members, shorter field time, and a wider, more flexible working range. At the same time, it introduces new requirements—up-front investment in GNSS equipment and a reliable communications link for corrections.

In the next section we will look at real-world RTK adoption cases and examine the concrete steps, equipment, and costs involved in making the switch.

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3. [Case Study] Successful Transitions from Total-Station to RTK Positioning

Case 1 – Boosting Productivity on a Large-Scale Civil-Engineering Project

At a major earth-moving job associated with a dam in Gunma Prefecture, the contractor faced an exceptionally tight deadline: work normally scheduled for a year had to be finished in just three months. Realising that conventional methods would never keep pace, Ikehara Kogyo Co. introduced an RTK-GPS surveying system to overhaul site efficiency. They combined Topcon GR-2100 RTK receivers with Fukui Computer’s civil-engineering software, using the setup for control-point work and as-built management.

The results were dramatic. Traditional surveys required two- or three-person crews and had to be carried out at dawn or late at night, when vibrations from earth-moving equipment subsided. With RTK, a single operator could survey during daytime machine operation without interference. Carrying the rover around the site, the surveyor logged each point with a single button press—less than 30 seconds per shot.

Survey data appeared instantly on a tablet, letting the crew compare measurements with design lines and verify as-built shapes on the spot. As the site supervisor put it, “Even on a large site, one person is enough for surveying now; the entire process has become astonishingly efficient.”

Being able to handle direction setting, distance and elevation checks, and even batter-board installation single-handedly was hailed on site as “a breakthrough for field engineers.”

As this case shows, introducing RTK on large-scale projects can be a decisive tool for shortening schedules. The gains in surveying efficiency created enough slack in overall progress that the team ultimately met a deadline many had deemed impossible. RTK is thus seen not merely as a tool for higher survey accuracy but as a technology capable of transforming the entire construction workflow.

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Case 2 – RTK in Infrastructure Maintenance (Expressways & Railways)
In infrastructure inspection and upkeep, RTK is now being deployed for assets such as expressways and railways, where wide-area, kilometre-scale structures must be monitored and their positions pinpointed precisely. Traditional route surveys and deformation checks relied on total stations and spirit leveling; introducing RTK has greatly increased efficiency and raised the technical level of these operations.

In rail applications, RTK has been used to monitor track distortion and settlement. Control points are installed along the line, and during routine patrols a rover measures each point’s height and position. Long-term changes can thus be detected to within a few centimetres. Work that once required time-consuming spirit leveling is now completed in real time, enabling earlier detection of anomalies and faster planning of repairs.

On expressways, RTK is employed to determine installation positions for tunnel and bridge equipment and to investigate pavement settlement or deformation. For example, when pinpointing a repair location, high-precision coordinates measured in advance with RTK can be loaded into a vehicle’s navigation system or a tablet; on site, the crew matches the real-time position to those coordinates to locate the defect exactly. This lets workers navigate a wide highway quickly and unerringly, shortening night-time lane closures and improving safety.

RTK is also being used to locate buried utilities in urban infrastructure. In one project, ground-penetrating radar (GPR) surveys were combined with RTK-GNSS: the exact position of each scan point was measured with RTK, the data were converted into 3-D coordinates, and a detailed map of underground pipes was produced. This has lowered excavation risks and enhanced the quality of maintenance drawings.

In short, RTK now delivers both accuracy and efficiency in infrastructure maintenance, enabling tasks that were once impractical. For engineers responsible for public assets such as expressways and railways, RTK is becoming a powerful new tool. Looking ahead, managers of different networks are expected to share a common, high-precision geodetic framework and standardise maintenance workflows that assume RTK accuracy from the outset.

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Case 3 – A Small Civil-Engineering Firm Boosts Its Competitiveness with RTK

Our final example comes from a small- to mid-sized civil-engineering and surveying company. Thanks to falling hardware prices and the expansion of subsidy programs, such firms have begun adopting RTK equipment in growing numbers. Behind this shift lies an urgent need to raise productivity—and thus remain competitive and sustainable—in the face of labor shortages and an aging workforce.

One regional surveying firm used to require a two- or three-person crew and an entire day to complete a land-parcel survey. After switching to a network-RTK service, a single technician now finishes the same job in less than half a day. Instead of installing its own base, the company connects one rover receiver to a commercial VRS correction feed, achieving centimetre-level accuracy instantly. Eliminating base-station hardware and setup cut equipment costs, and the field time for each survey dropped by more than 30 percent. Freed-up staff could tackle additional projects, boosting overall throughput. “The clear benefits are that it’s easier and faster,” the manager notes—no more back-and-forth trips with a total station now that RTK handles the job in one pass.

Another small construction firm combined ground-based RTK with an RTK-enabled drone on a mountainside earth-work site, dramatically shortening the overall survey time. Instead of installing the many ground control points that used to keep a survey crew busy for half a day, the RTK drone captured aerial photographs and generated a 3-D terrain model, while ground staff used RTK only to verify a few key positions. The company achieved the same accuracy as with the traditional method yet cut the end-to-end surveying process by about 50 percent. The system also let younger operators deliver high-quality results with the latest ICT tools—an advantage for both training and corporate image.

RTK technology, then, yields strong returns not only for large contractors but for small and mid-sized companies as well. In fact, Japan’s “Subsidy for Labor-Saving Investments by SMEs” lists RTK GNSS equipment among the eligible products, allowing firms to offset part of the initial cost. With such support lowering the investment barrier, even more small businesses are expected to adopt RTK and help raise the industry’s overall productivity.

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4. Practical Steps for Introducing RTK

Required Equipment and Up-Front Costs

(GNSS rover, base station, software)

To deploy RTK positioning, you will need the following primary components:

• GNSS Rover Receiver:
  The portable unit that the surveyor carries to each point. Most models combine an antenna and receiver at the top of a survey pole, capturing satellite signals and applying real-time corrections.

• Base-Station Receiver:
  Required if you install your own base. Mounted over a known control point, it observes continuously and transmits correction data to the rover. Choose a model with precision and stability equal to—or better than—the rover.

• Communication Hardware (radio or mobile router):
  A link for sending correction data from the base to the rover in real time. Options include low-power or UHF radios, or Internet delivery via Ntrip. Today the common approach is to equip the rover with a SIM card and receive corrections over the cellular network.

• Field Controller / Software:
  A handheld controller or tablet that displays and records rover coordinates and guides stake-out operations. Dedicated field computers or tablets run software for point naming, notes, codes, and other metadata.

• Auxiliary Gear:
  Tripod (for the base), survey pole or prism (if used alongside a total station or for check measurements), spare batteries, sun shades, and other site-specific accessories.

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The upfront cost varies with receiver performance, manufacturer, and operating method, but a typical dual-frequency RTK-GNSS set can be introduced for a few million yen (tens of thousands of dollars). High-end packages may run ¥5 – 8 million (roughly USD 35 000–55 000), yet an increasing number of reasonably priced models—especially from overseas vendors—are now available. If you take advantage of the subsidy programme mentioned earlier, up to half the purchase price can be covered, allowing even small and medium-sized firms to obtain state-of-the-art RTK equipment for well under several million yen in net cost.

Another option is to skip installing your own base station and instead subscribe to a commercial network-RTK service (annual or pay-as-you-go). In that case, the initial investment is limited to a single rover receiver. Choose the equipment configuration and procurement route that best fits your needs and budget.

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Preparing to Use RTK (setting up a base station or using network RTK)

To run RTK positioning you must have a way to obtain correction data from a base station while in the field. Broadly speaking, there are two approaches.

1. Installing your own base station:
   Set up a company-owned GNSS receiver at the site (or on a nearby known control point) as the base station. Mount it firmly on a tripod or fixed pillar so it can observe satellites continuously. Beforehand, determine the installation point’s precise latitude, longitude, and ellipsoidal height from a national control point (e.g., Japan’s GSI electronic reference stations) or another known benchmark. The base then transmits real-time correction data (RTCM, etc.) to the rover via low-power or UHF radios set to the same frequency. This self-contained base-station method is especially effective in remote areas where public communications infrastructure is limited.

2. Using a network-RTK service:
   Instead of installing your own base, you subscribe to an external correction service. Across Japan, both the national electronic reference-station network and private GNSS networks provide such feeds, typically via VRS/VDRS (network RTK) solutions. Equip the rover with Internet access—usually over a cellular connection—and log in to the provider’s Ntrip server; the system delivers corrections generated from the reference stations nearest your current location. Thus a single receiver can perform RTK positioning without any on-site base. This method is especially convenient in urban areas or when the survey involves wide-area travel.

Whichever method you choose, it is vital to keep the base-station datum consistent with the site’s working coordinate system. For public surveys in Japan, positions are usually expressed in the JGD2011 Plane Rectangular Coordinate System, so you must verify that the rover outputs coordinates in the expected datum (and set datum transformations or geoid corrections in the receiver if necessary). Before starting the job, always perform a test measurement on a known control point to confirm that both the base and rover are tracking satellites correctly, receiving corrections, and delivering the required accuracy.

Another essential part of the preparation is training the technicians who will operate the system. Make sure they are familiar with RTK-specific concepts—such as fixed vs. float solutions and GDOP values—and know how to react to issues like satellite loss and solution re-initialisation. Sharing this knowledge in advance ensures smoother field operations. Taking advantage of training sessions offered by equipment suppliers or correction-service providers is highly recommended.

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Workflow for RTK Surveying vs. Total-Station Surveying

The basic workflow of an RTK survey is far simpler than that of a traditional total-station survey.

1. Base-station setup:
   Own-base method – Mount the base receiver on a known control point at the site, power it on, and start positioning. Enter the precise coordinates and begin transmitting correction data to the rover.
   Network-RTK method – On the rover’s controller, log in to the correction service and start receiving the correction stream.

2. Starting rover positioning:
   Switch on the rover receiver and wait for it to receive the base-station corrections and enter RTK “fixed” mode. This typically takes only a few seconds to a few tens of seconds. Once the solution is stable, confirm the current coordinates on your data collector or tablet.

3. Point observation:
   Position the rover (the GNSS antenna at the top of the pole) precisely over the point to be surveyed. Use the pole’s bubble to make it plumb, then press the record button to begin the measurement. The receiver observes for a few seconds (or as configured), averages the data, and automatically stores the point’s coordinates in the controller. Each point typically takes only a few seconds to record. Enter a point name, feature code, or notes as required.

4. Repeat observations:
   Move on to the next point and take a measurement in the same way. Even when you have many points, you can record them continuously as you walk, keeping the work flowing without interruption. Because line-of-sight between stations is unnecessary, you are free to survey points in whatever order best suits the terrain.

5. Check & wrap-up:
   After surveying all required points, return to a known control point and take a check measurement to confirm that no positional drift has occurred. If the results are satisfactory, the survey is complete. Dismantle the base station and switch off the rover. Transfer the recorded coordinate data from the controller to a PC—via USB stick or cloud upload—for drafting and analysis.

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By contrast, the workflow with a total station looks like this:

1. Set up the instrument over a known point, sight and range to a backsight target, and zero the horizontal angle.

2. Sight and range to the foresight prism, then record the observation.

3. Move the instrument to the next setup point, backsight the previous point or another known point, reset the instrument, and repeat the process for each successive station.

As the comparison shows, RTK eliminates virtually all of the “tear-down and re-set” work that dominates total-station surveying. Because the operator simply walks around with the rover, there is no need to set up a tripod, take a shot, pack up, and start over at every point—an immediate boost in productivity.
Another advantage is that RTK produces numeric coordinate data in real time, ready for direct import into GIS or CAD. Intermediate calculations that convert angles and distances to coordinates disappear, along with the possibility of human error.

RTK also simplifies height measurement. As long as the antenna height is entered correctly, each point’s elevation is computed automatically; with a geoid model, orthometric (sea-level) heights are generated on the spot, reducing the need for separate levelling.

That said, traditional instruments are not obsolete. Total stations remain essential for verification and for environments where GNSS signals are blocked—tunnels, dense forest, urban canyons—and precise spirit levelling is still required when millimetre-level vertical accuracy is demanded. In practice, successful sites blend RTK with TS and levels, leveraging the strengths of each. Many crews report “we still double-check critical elevations with a level,” illustrating the complementary approach.

With the right gear, careful setup, and proper training, RTK is surprisingly easy to master. Users often say, “Once the base is up, you just walk the site with the rover—one point takes less than 30 seconds.” After experiencing that workflow, few want to return to conventional methods.
In the next section we introduce LRTK, a new device that makes RTK even more accessible.

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5. Introducing LRTK — Free Information Pack Available

Key features – compact, lightweight, yet highly accurate

Getting the most out of RTK requires equipment that is easy to handle. LRTK, developed by Refixia Inc. (a Tokyo Tech spin-off), is a pocket-sized “all-in-one” surveying device designed with exactly that in mind. Weighing just 125 g and only 13 mm thick, this ultra-compact RTK-GNSS receiver snaps into a dedicated smartphone case in one click. In other words, combined with an iPhone or iPad it instantly transforms your handset into a centimetre-class surveying instrument.

Despite its tiny size, LRTK delivers accuracy on a par with conventional tripod-mounted RTK receivers—planimetric errors stay within a few centimetres. Bench tests show single-epoch accuracy of about 12 mm, improving to ≈ 8 mm when the internal averaging function is enabled—more than sufficient for professional survey work.

A companion app streamlines the entire workflow—from point capture to data logging and cloud sharing. Press the Measure button and the app automatically stores latitude, longitude, ellipsoidal height, timestamp, and solution status; you can attach notes and photos on the spot. With a single tap the data syncs to the cloud, so staff back at the office can view results immediately. The app also performs on-device conversions to Japan’s plane-rectangular coordinates and applies the geoid height model automatically, eliminating cumbersome post-processing.

Functionally, LRTK handles high-precision positioning, point-cloud capture, stake-out, and even AR visualization. Paired with an iPhone’s LiDAR scanner and camera, it can collect dense point clouds or overlay design models onto live video for real-time AR simulations. For example, stake-out work that once required cross-checking paper plans can now be performed intuitively: survey points appear as AR markers on the phone display, and the app navigates you directly to the target coordinates.

Despite this rich feature set, LRTK is priced very competitively. Without investing in bulky dedicated gear, a single smartphone + LRTK kit per person covers everything from topographic survey to as-built checks. True to the developers’ goal of providing a “carry-everywhere, one-device-per-worker field tool,” LRTK is quietly becoming a favorite among site professionals.

(Free literature and pricing details are available on request.)

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Use-case and results on an active construction site
LRTK has already been rolled out on several jobs, and its benefits have been verified. At one road-construction site, the site supervisor carried an LRTK unit at all times and used it for day-to-day as-built checks. Because the supervisor could compare the design drawings with on-site conditions personally—without calling in specialist surveyors—the work stoppages caused by “waiting for verification” disappeared. As a result, the time-lag between construction and measurement vanished, quality assurance became easier, and the risk of rework due to out-of-tolerance work was reduced. One supervisor even remarked, “With LRTK I no longer need any pens on site.” Since point notes and field-book entries were digitised, the time required for report preparation and other paperwork was also drastically cut.

In another case, LRTK was deployed for infrastructure-inspection work. An inspector wore a helmet-mounted LRTK unit (one of the available variants) and, when photographing structural elements, each image was automatically tagged with centimeter-level position coordinates and camera orientation. Back in the office, staff could reopen the photos and see exactly “where each shot was taken from and in which direction” on a map, greatly enhancing the reliability of the inspection data. The manual task of writing location information on every photo was eliminated, and report-preparation efficiency improved dramatically. Trials have also begun using LRTK’s AR capability to compare on-site deformation points with 3-D models, accelerating the digital transformation (DX) of infrastructure maintenance.

In this way, LRTK demonstrates enormous potential as an intuitive tool that even field crews with no specialist knowledge of high-precision positioning can use right away. The message is clear: “Harness centimeter-level accuracy to accelerate the DX of construction management and surveying. By pairing RTK technology with LRTK devices, on-site productivity and safety will soar.” LRTK is therefore expected to become the new standard on tomorrow’s construction sites.