Five Advantages of RTK Cross-Sections: The Secret to Combining High Precision and Efficiency

Table of Contents

• What is an RTK cross-section?

• Advantage 1: Enables centimeter-level high-precision measurement

• Advantage 2: Shorter surveying time and improved efficiency

• Advantage 3: One-person surveying and simplified equipment

• Advantage 4: Improved safety at hazardous sites

• Advantage 5: Detailed cross-sections from 3D data and immediate usability

• Simple surveying with LRTK

• FAQ

What is an RTK cross-section?

In civil engineering and construction sites, there are frequent opportunities to create cross-sections of terrain and structures. A cross-section is a depiction of a vertical slice through the ground surface or a structure and is used to intuitively understand elevation differences and the shape of subsurface structures. For example, in roadworks, transverse cross-sections along the alignment are used to check whether finished elevations and gradients match the design. In river and levee works, transverse sections of the river are measured periodically to monitor deposition and erosion. Cross-sections are also used to verify as-built conditions and to calculate quantities, making them one of the indispensable record drawings for construction.

However, creating cross-sections by conventional methods required a lot of effort. Typically, surveying staff used instruments such as levels or total stations to measure elevations at points along the cross-section line and then drew the cross-section line on drawings based on that set of points. This method had the following issues:

• Requires manpower and time: Measuring a single cross-section typically required at least two workers (a measurer and a recorder), and for long stretches the surveying instrument had to be reinstalled multiple times, sometimes taking several days.

• Hazardous work: On steep slopes or riverbanks, workers had to enter dangerous areas to place poles, creating constant safety risks such as slips and falls.

• Limits in accuracy and coverage: Because points were collected manually at intervals of a few meters (several meters (several ft)), fine undulations between points could be missed. Even if you later think “we should have measured more finely,” you must return to the site to re-measure.

• Laborious drafting: Bringing field point data back to the office and entering it into CAD to draw cross-sections was cumbersome, and the effort multiplied when there were multiple sections. Manual input also introduced risks of transcription errors and drawing mistakes.

• Equipment and cost burden: Obtaining higher-precision cross-sections sometimes required expensive surveying instruments or 3D laser scanners, which may be unrealistic cost-wise for small sites.

Thus, traditional methods demanded substantial personnel and time and had challenges in both efficiency and accuracy. Although the need for “more efficient and more accurate cross-section measurement” has long been strong, effective solutions were limited until now.

What has attracted attention is the use of high-precision GNSS positioning by the RTK method. RTK (Real Time Kinematic) is a positioning technology that corrects satellite positioning errors in real time with correction data from a base station, enabling position determination with accuracy within a few centimeters (within a few inches). Traditionally, specialized high-performance GNSS equipment was required, but recently it has become possible to achieve centimeter-class positioning easily by combining compact RTK-capable receivers with smartphones. An RTK cross-section refers to a cross-section created by applying this high-precision RTK positioning to field cross-section surveying; it is a new method that realizes improved efficiency while ensuring high accuracy.

The next chapter explains five advantages that RTK-based cross-section creation brings to the field. Let’s look at the secrets of how it achieves both high precision and efficiency.

Advantage 1: Enables centimeter-level high-precision measurement

The greatest advantage of RTK-based cross-section surveying is, above all, its high positioning accuracy. With RTK-GNSS surveying, by applying corrections to the positional information obtained from satellites, points can typically be measured with extremely high accuracy—on the order of a few centimeters (a few inches) in both horizontal and vertical directions. This accuracy is comparable to conventional surveying using total stations or levels, providing sufficient reliability for cross-section creation. Conventional handheld GPS produced errors on the order of several meters (several ft) and was unusable for cross-sections, but RTK measures in the “world of a few centimeters (a few inches)”, allowing even slight elevation differences relative to design drawings to be captured accurately.

In addition, the coordinates of each point obtained by RTK positioning are obtained as absolute coordinates based on the Geospatial Information Authority of Japan’s reference coordinate system. This means that the measured points can be overlaid directly onto electronic maps or design drawings without complex coordinate transformations. Conventional surveying often required local site-specific references, but with RTK you can always measure in a unified standard without troublesome conversions. As a result, data consistency and comparative analysis in downstream processes become smooth, further enhancing the accuracy and reliability of cross-sections.

The ability to simplify work while maintaining high accuracy is a major strength of RTK cross-sections. Distinguished from the old quick-but-inaccurate simple surveys, RTK is a method that achieves both speed and precision, contributing to on-site quality control.

Advantage 2: Shorter surveying time and improved efficiency

By adopting the RTK cross-section method, you can greatly reduce the time required for field surveying. Traditionally, surveyors measured points at regular intervals along the cross-section line and repeatedly reinstalled tripods as needed, so transverse surveys over long sections could take a full day. RTK transforms this inefficient process. With a compact GNSS receiver attached to a smartphone, an operator can simply walk along the cross-section line and record measurement points one after another, completing the survey. There is no need to split into measurer and recorder, and because data can be collected continuously while moving, subjectively the surveying proceeds several times faster than the conventional approach.

Especially when there are multiple cross-sections to measure or long stretches of roads or rivers to handle, the efficiency gains from RTK are enormous. Cases that previously required setting up equipment for each section and several days of work can, with RTK, have the necessary data obtained quickly on the spot. Reduced field surveying time translates directly into shorter overall construction schedules. On sites where many tasks must be completed within limited days, RTK cross-sections’ rapid data acquisition is a great help.

Furthermore, because RTK positioning provides high-precision coordinates in real time, it is efficient to confirm measurement results on site immediately. Measured points are plotted on a map on the spot, allowing you to check whether “the required area has been sufficiently covered” or if there are any omissions. This prevents the need to bring data back to the office only to find deficiencies and return for re-surveying. In this way, RTK cross-sections enable an efficient workflow that reliably achieves results in a single field visit.

Advantage 3: One-person surveying and simplified equipment

RTK cross-sections also achieve significant labor and equipment savings. Conventional surveying is generally done in pairs of two or more people, but with RTK a single person can basically complete the survey. There is no need for an assistant to hold a prism or to read and record aloud. A field engineer can carry a smartphone and perform measurements alone, making cross-section surveying feasible even on sites with labor shortages or small-scale projects. Also, the equipment is extremely simple. There is no need to carry heavy tripods or mounted surveying instruments—just a palm-sized GNSS receiver and a smartphone are enough. The burden of transporting equipment is reduced, and moving through narrow or elevated areas becomes easier. Small equipment also means minimal transport costs by vehicle or by manpower and minimal time spent preparing for surveying.

With simpler equipment, routine maintenance and calibration burdens are also reduced. Total stations require periodic accuracy management, but RTK GNSS receivers are basically electronic devices with almost no dedicated calibration work required. Function checks and updates can be done through a smartphone app, freeing you from complex preparation tasks before going to the field.

The ease of operation is another noteworthy point. A smartphone screen displays the current position and accuracy information, and an intuitive interface that allows recording points with a single button makes the system easy to use even for staff with limited surveying experience. Cross-section surveying that used to depend on experienced surveyors can, with RTK, be performed easily by site supervisors and workers themselves. Shifting from person-dependent tasks to team-shared workflows contributes to workplace reform on site.

Advantage 4: Improved safety at hazardous sites

The safety risks long associated with surveying work can be reduced with RTK cross-sections. With conventional methods, workers had to enter dangerous areas such as steep slopes or riverbank revetments to place poles while another person sighted from a distance. Installing instruments on unstable slopes and coordinating between staff is hazardous and carries constant risks like falls and heatstroke. RTK minimizes the time spent working in such danger zones. Because surveying can be completed in a short time, opportunities for exposure to hazards are reduced, leading to lower risk of occupational accidents. The fact that one person can perform the work is especially significant, as it avoids situations where multiple people are simultaneously in hazardous areas and thus markedly improves safety.

Additionally, the simplicity and high mobility of the equipment are safety benefits. There is no need to carry heavy tripods or mounted instruments across slopes, reducing physical strain on workers. Being light and agile lowers the likelihood of awkward postures when operating equipment in confined or elevated locations. For transverse surveys on busy roads, measurements can be completed quickly and staff can evacuate immediately, contributing to reduced traffic accident risks.

In some cases, remote measurement is also possible. Utilizing smartphone cameras or LiDAR point cloud scans allows recording the shape of objects from safe locations where survey staff cannot enter. If data can be obtained without approaching directly, even highly hazardous sites can be surveyed safely. Thus, RTK cross-sections excel not only in accuracy and efficiency but also in ensuring on-site work safety.

Advantage 5: Detailed cross-sections from 3D data and immediate usability

The RTK cross-section method dramatically improves the quality and usability of acquired data. By using a smartphone’s LiDAR scanner or camera to record the site as a 3D point cloud, you can measure every detail of terrain and structures without omission. A point cloud, composed of countless points, captures even subtle surface irregularities, so cross-sections generated from that data accurately reflect the true on-site shape. Small depressions or bulges that conventional methods might miss are captured in a point cloud cross-section. This prevents situations where “an unmeasured area is not reflected in the drawing” and enhances the completeness and precision of drawings.

Moreover, once 3D data is acquired, it can be analyzed and utilized flexibly as needed. For example, from a point cloud model uploaded to the cloud, you can extract cross-sections at any desired location. If a cross-section at a line not measured on site is needed later, there is no need to re-survey. With a point cloud, transverse and longitudinal sections can be automatically generated at arbitrary angles and intervals. Beyond cross-sections, 3D data can be used for volume calculations, as-built management, and other applications—allowing multifaceted use of the data.

Because the data is digitized, the process to produce drawings is also automated and accelerated. Point cloud data collected in the field can be processed quickly by dedicated software or cloud services to instantly generate high-precision cross-sections. Cross-sections that previously required returning to the office to refine in CAD can, with RTK, be output as electronic drawings immediately after field measurement. This makes it possible to compare as-built conditions with the design on site and to share data with stakeholders, enabling real-time decision-making. This speed from digitalization is a major factor supporting DX (digital transformation) in construction management.

Simple surveying with LRTK

As described so far, creating cross-sections using RTK offers numerous benefits in terms of accuracy, efficiency, and safety. The key to actually realizing these benefits on site is the latest digital surveying tool, “LRTK.” LRTK is a high-precision positioning system composed of a compact RTK-GNSS receiver, a smartphone app, and cloud services, and it has emerged as a solution that promotes DX in cross-section creation.

With LRTK, you can perform easy centimeter accuracy (half-inch accuracy) surveying without preparing specialized surveying instruments. Simply attach the receiver to your smartphone and launch the app to receive correction information in real time and obtain high-precision position information. You can walk around the site holding your phone, record measurement points with button operations, or scan the surroundings with the camera to acquire point cloud data. Acquired data is immediately synchronized to the cloud and automatically analyzed and drawn, so completing cross-sections while on site is no longer a dream. Tasks that used to require outsourcing or special equipment become a simple workflow anyone can handle with LRTK.

LRTK, which achieves the trio of labor savings, speed-up, and quality improvement, is becoming the standard for future field surveying. If you are thinking “I want to make cross-section creation more efficient” or “I want to DX my site with the latest technology,” consider simple surveying with LRTK. It will likely lead directly to discoveries that reform your on-site workflows.

FAQ

Q1. What is an RTK cross-section? A. An RTK cross-section is a cross-section created by surveying and recording field cross-sectional shapes using high-precision GNSS positioning via the RTK method. RTK technology can measure positions in real time with centimeter accuracy, allowing rapid and accurate recording of terrain cross-section profiles. It offers comparable accuracy to cross-sections created by conventional surveying while significantly improving work efficiency.

Q2. What is required to use RTK positioning? A. To perform RTK positioning, you need an RTK-capable GNSS receiver and a reference station system that provides position correction information. Generally, in addition to the GNSS terminal (rover) used for the mobile station, a base station that transmits correction signals is prepared. Even if you do not install your own base station, you can obtain equivalent correction information by connecting via the Internet to network-type reference station services (GNSS correction services) provided by the Geospatial Information Authority of Japan or private companies. You also need a device (PC, tablet, or smartphone) and software to operate and record with those receivers. Using a package that integrates smartphone, compact receiver, and cloud services—such as LRTK—allows you to start RTK positioning without assembling specialized equipment.

Q3. How accurate is RTK surveying? A. With RTK-GNSS surveying, under good positioning conditions, errors are expected to be on the order of a few centimeters (a few inches) horizontally and vertically. In well-conditioned situations, planar positions often fall within about 2-3 cm (0.8-1.2 in) and elevations within about 3-5 cm (1.2-2.0 in), which is sufficient accuracy for usual civil surveying purposes. However, accuracy is affected by satellite signal reception conditions. Open skies provide high accuracy, while mountainous areas, under trees, or in the shadow of buildings can block satellites and reduce accuracy. Performing measurements in appropriate environments and ensuring that RTK maintains a fixed solution (Fix) during surveying are keys to achieving high accuracy.

Q4. Is specialized knowledge required for RTK surveying? A. While handling conventional surveying instruments required specialized knowledge and experience, RTK surveying itself can be performed without advanced expertise as long as basic operational procedures are followed. Smartphone-compatible systems like LRTK display positioning accuracy and satellite reception status clearly on the app and allow measurements with button operations. After completing initial setup according to the manual and ensuring correction information is received correctly, you can proceed by following the on-screen instructions. Basic surveying knowledge (such as the concept of control points and coordinate systems) provides reassurance, but the system is designed so that non-expert users can operate it effectively on site.

Q5. What sites can LRTK be used for? A. LRTK can be used at various sites that require high-precision positioning and 3D data measurement. For example, in roadworks it helps confirm subgrade heights and measure cross-sections of embankments and cuttings; in river and erosion control it supports cross-section monitoring of deposited sediment; in land development it assists with as-built volume calculations and ground shape checks. On steep slope works, scanning from below without scaffolding can record the overall shape safely and efficiently. For small-scale projects that used to outsource surveying, LRTK enables in-house surveying and drawing. Beyond construction, LRTK is powerful in any situation where you need to quickly and accurately record on-site shapes, such as disaster site surveys after landslides or inspections and maintenance of infrastructure.