Differences Between RTK and Traditional Surveying in Construction: How Do Accuracy and Efficiency Change?

Table of Contents

• What is RTK surveying?

• What is traditional surveying?

• Differences in accuracy

• Differences in efficiency

• Examples of RTK use on construction sites

• Benefits of introducing RTK

• Challenges in RTK implementation

• Simple surveying enabled by LRTK

• Summary

• FAQ

In recent years, a satellite positioning technology called RTK (real-time kinematic) has been increasingly adopted for surveying on construction sites. How do the accuracy and efficiency of RTK surveying differ from traditional methods? This article explains the differences between RTK-based surveying and conventional surveying methods, and introduces the benefits and use cases for the construction industry. Traditionally, surveying relied on the manual work of experienced surveyors, but with the introduction of RTK, anyone can perform precise measurements in a short time. Because data can be acquired in digital form, it also contributes to improved construction efficiency and higher-quality control.

What is RTK surveying?

RTK surveying is one of the high-precision positioning methods that uses GNSS (global navigation satellite systems). Ordinary GPS positioning can produce errors on the order of several meters, but RTK enables real-time centimeter-level (cm level accuracy, half-inch accuracy) high-precision positioning. Specifically, it uses two receivers—a base station (a fixed receiver) and a rover (the receiver to be positioned)—and cancels errors by taking the difference between the satellite signals received simultaneously by both. As a result, a positional deviation that would be “about the size of a soccer ball” with static satellite positioning is reduced to a “fingertip-sized” tiny error with RTK. Using RTK surveying, accurate coordinates of a site can be obtained in a short time, and the survey results can be immediately utilized in construction.

What is traditional surveying?

By traditional surveying methods we mean conventional, non-satellite-based surveying techniques. Typical examples include surveying using total stations (electro-optical distance meters) and auto levels (leveling instruments). A total station measures distance and angles to a prism using emitted light or radio waves from the instrument, enabling high-precision measurement of the relative positions of terrain and structures. An auto level is an instrument for precisely measuring height (elevation) differences by establishing a horizontal line of sight. With these conventional methods, it was common to set up instruments and establish control points for each survey, and to work with two or more people—placing prisms or staffs at target points while another person operates the instrument. Line surveys and leveling require line of sight and proceed point by point, so large sites or complex terrain required substantial time and effort. Although total stations have become electronic and data linkage has advanced, the basic surveying procedures still depend largely on manual labor.

Differences in accuracy

There are also differences in achievable accuracy between RTK surveying and traditional surveying. With traditional surveying using a total station, millimeter-level accuracy can be expected over short distances. If a skilled surveyor carefully observes from control points, extremely high accuracy can be achieved for layout of structures and the like. On the other hand, with RTK surveying, positions can be determined with horizontal errors of about 2–3 cm (0.8–1.2 in) and vertical errors of about 3–5 cm (1.2–2.0 in). This range of a few centimeters is orders of magnitude more precise than ordinary GPS (errors of several meters). Looking only at absolute accuracy, optical surveying instruments that can pursue millimeter-level precision may outperform RTK in some cases. However, RTK has the advantage of being able to position the entire site at once. Even over wide areas, errors are less likely to accumulate, and the terrain as a whole can be efficiently grasped to centimeter-level accuracy. When surveying in multiple sessions, all measured points are obtained in a common reference coordinate system, producing consistency in results even on large sites. Because RTK uses correction information from a base station, error sources that arise during observation (such as satellite orbit errors and atmospheric effects) can be reduced in real time. Under good conditions, the practical accuracy difference between RTK and optical surveying is very small. For example, in topographic surveys or in the management of earthworks and excavations, a few centimeters of error is often sufficient.

Differences in efficiency

There are also large differences in work efficiency between RTK surveying and traditional surveying. First, traditional surveying often assumes multiple people working together, with a surveyor and an assistant required even to measure a single point. When surveying a large site, each time the instrument is repositioned a new control setup is required, which takes time. In contrast, RTK surveying allows one person to efficiently survey using a single rover receiver. The operator can walk the site holding the rover and obtain coordinates for point after point. Because line of sight is not required, on open sites with few obstructions many points can be recorded in a short time. Also, RTK receivers are small and lightweight, so there is no need to carry heavy tripods or equipment, greatly reducing physical burden on site. For example, a topographic survey that used to take half a day can in some cases be completed in several tens of minutes to about an hour with RTK. In staking out and layout (piling and marking) work, traditionally a surveyor would operate the instrument while another worker drove piles or marked lines, but with RTK-compatible equipment one person can both operate the equipment and confirm pile positions simultaneously, greatly simplifying setup. Overall, RTK adoption enables labor savings and speed-ups in surveying work, leading to shorter schedules and reduced labor costs.

Examples of RTK use on construction sites

Because RTK can obtain high-precision position information in real time, it is used in many aspects of construction and civil engineering. Below are major use cases.

• Topography and land surveys: For earthworks and pre-development surveys, RTK can acquire wide-area topographic data in a short time. Areas that used to take several days with traditional total station surveys can see dramatic efficiency improvements with RTK. The obtained coordinate data can be immediately imported into electronic maps or CAD, making it quickly useful for design and volume calculations.

• Construction layout (piling and marking): Staking out and marking tasks that indicate the precise position and elevation of structures are critical and require accuracy. Using RTK-capable surveying equipment, design coordinates can be confirmed on site instantly, and a single person can mark pile positions. Repeated re-measurement is reduced, and work time can be shortened while maintaining construction accuracy.

• As-built and quality control: RTK is also useful for checking as-built conditions after paving or earthworks. Heights and slopes of the ground and structures after construction can be measured at many points and quickly compared with design values. Especially when collecting as-built data over wide areas, RTK can obtain high-density measurement points in a short time, improving the accuracy of quality control.

• ICT construction and machine guidance: In ICT-enabled construction, commonly used today, GNSS receivers are mounted on heavy machinery such as bulldozers and excavators and linked with design data to automatically control machines. With RTK’s high-precision positioning, operators can know the exact position of the blade tip in real time and proceed with construction with fewer stakes and surveying tasks. This contributes to labor savings and improved safety on construction sites.

• Drone surveying: Equipping photogrammetry drones with RTK greatly improves the positional accuracy of aerial photographs. Even in cases where many ground control points were previously required, an RTK drone can create a high-precision 3D survey model with fewer control points. It enables efficient data acquisition from the air for tasks such as surveying in mountainous areas or calculating earthwork volumes on large development sites, and is powerful for construction management and progress monitoring.

As these examples show, RTK surveying is revolutionizing fieldwork on both surveying and construction fronts. What was once the domain of specialists like surveyors is now increasingly handled by site engineers themselves as instruments become smaller and less expensive. For productivity improvement and quality assurance on construction sites, RTK usage is becoming indispensable.

Benefits of introducing RTK

The benefits of introducing RTK surveying on site are wide-ranging. First is the dramatic improvement in work productivity. Because surveying can be completed by one person, survey personnel can be reduced and resources can be allocated to other tasks. Work time is greatly shortened, allowing tasks that previously waited for surveying to proceed quickly. This can lead to shorter overall schedules and cost reductions. Also, since RTK obtains survey results as digital data on site, it contributes to more efficient data utilization. The need to transcribe values from paper field books into CAD at the office disappears; coordinates can be shared to the cloud or imported into design software on the spot. Furthermore, the spread of RTK contributes to improved safety. Traditional surveying sometimes required entering hazardous areas or working at night with limited visibility, but GNSS positioning allows measurements from a distance without entering danger zones, and confirmation is possible on device screens even in the dark. Overall, RTK adoption transforms how sites operate and is a key driver of construction DX (digital transformation). These effects align with the Ministry of Land, Infrastructure, Transport and Tourism’s i-Construction initiative (improving construction site productivity through ICT), making RTK an important element supporting site digitization.

Challenges in RTK implementation

On the other hand, several challenges have been pointed out regarding field implementation of RTK technology. First is the scale and cost of equipment. Traditional RTK systems required base station receivers, communication devices, rover poles and antennas, external batteries, and many other pieces of equipment to carry, making initial costs high. This reality made RTK adoption a high hurdle especially for small and medium-sized contractors. Next, operational difficulty is also a challenge. Achieving high precision requires expertise in configuring base-rover communications, GNSS knowledge, and handling coordinate systems; without trained survey technicians, it can be difficult to use RTK effectively. Dependence on the measurement environment is another factor. In urban canyons surrounded by tall buildings or in forested mountainous areas, satellite signal reception can be unstable and RTK accuracy may not be achieved. Also, on sites outside of communication coverage, networked RTK cannot be used, so systems capable of offline correction or preparations for radio communication are necessary. To make full use of RTK, equipment, cost, and technical hurdles must be overcome.

Simple surveying enabled by LRTK

With growing demand for RTK technology, recently products that make traditional RTK equipment even more user-friendly have appeared. A representative example is the small GNSS positioning system called LRTK. It was developed to solve conventional challenges and to enable anyone, anywhere, anytime to use RTK. Conventional RTK surveying gear required a tripod-based base station, a rover mounted on a long pole, radios, external batteries, and many other items to bring to site, with correspondingly high initial costs that posed barriers for small- to medium-sized contractors. The LRTK series achieves significant miniaturization, weight reduction, and a simple configuration. For example, the smartphone-integrated LRTK Phone houses the receiver, antenna, communication module, and battery in a single device weighing only a few hundred grams. No complicated cables are needed; it connects wirelessly to a smartphone. On site, you can take it out of your pocket and start surveying immediately, intuitively checking points, entering point names on the phone screen, and saving data to the cloud. Prices are set to be more affordable than conventional products, and it may become realistic for each person to have their own device in the future.

Technically, LRTK also incorporates the latest solutions. High-performance GNSS receivers supporting multiple frequencies make it easier to obtain stable positioning solutions even in urban streets or mountainous areas where it used to be difficult. It also supports the centimeter-level augmentation service (CLAS) provided by Japan’s quasi-zenith satellite system “Michibiki,” allowing high-precision positioning to continue via satellite augmentation even where mobile signals cannot reach. This enables RTK-equivalent positioning in mountain remote areas or disaster sites where internet-based base station services are unavailable. By combining intuitive operability that requires no specialist knowledge with advanced positioning technology, LRTK is attracting attention as an RTK surveying device anyone can use on site. Local governments and construction companies are already adopting it for disaster response and infrastructure maintenance. The advent of LRTK truly marks the beginning of an era of “surveying with a smartphone.”

Summary

Summarizing the differences between RTK surveying and traditional surveying, the contrast appears as accuracy: a few centimeters vs. millimeter-level, and efficiency: single-person work vs. multi-person work. RTK may not match conventional instruments in absolute accuracy in all cases, but it is extremely useful as a tool to improve productivity across construction sites. Its strength in surveying wide areas quickly and the ease of digital integration are RTK-specific advantages not found with traditional surveying. Of course, appropriate choice is important—optical surveying is still necessary inside tunnels or buildings, or for machine installations requiring millimeter accuracy. However, as ICT continues to advance in the construction industry, the use of RTK technology is an unavoidable trend. Solutions like LRTK, which make RTK accessible to everyone, are expected to make site surveying more familiar and efficient. As many engineers—not just professional surveyors—become proficient with RTK, the productivity and accuracy of construction sites will further improve. In an industry facing chronic labor shortages, such technological innovation could be the key to labor and efficiency gains.

FAQ

Q: What is the difference between RTK and ordinary GPS positioning? A: Ordinary GPS (GNSS) positioning is performed with a single receiver and therefore has errors on the order of several meters. RTK, on the other hand, performs relative positioning with a base station and corrects satellite positioning errors in real time to achieve centimeter-level accuracy. In short, RTK is a technology that dramatically improves GPS accuracy.

Q: What is required to perform RTK surveying? A: Basically, an RTK-capable GNSS receiver (rover) and a base station that the receiver refers to are required. The base station can be set up locally or you can use networked base station services (GNSS reference stations) provided by government or private entities. The rover receives correction information via communication and performs real-time high-precision positioning. Recently, small RTK devices that can be linked with smartphones (for example, the LRTK series) have appeared, making it possible to start RTK surveying easily without specialized equipment.

Q: How reliable is RTK surveying accuracy? A: If operated correctly in an open environment, RTK positioning can achieve horizontal accuracy of about 2–3 cm (0.8–1.2 in) and vertical accuracy of about 3–5 cm (1.2–2.0 in). This is sufficient for most construction surveying and as-built checks. However, in environments where satellite signals are disturbed—such as between tall buildings or in dense forests—accuracy can degrade or positioning can become unstable. For important measurements, check satellite reception conditions and, if necessary, re-measure or choose appropriate time windows.

Q: If we have RTK, is traditional surveying no longer necessary? A: RTK is a very convenient technology, but traditional surveying techniques are not rendered entirely unnecessary. For example, surveying inside tunnels or buildings, or machine installations that require millimeter-level accuracy, still call for optical total stations or levels. RTK surveying itself also requires preliminary known-point surveys and checks to ensure accuracy. It is important to use RTK and traditional methods appropriately based on site conditions.

Q: How can survey data obtained with RTK be utilized? A: Coordinates obtained with RTK are in digital form and can be used in various ways. For example, point data can be imported into CAD software to create drawings, or compared with design data for as-built management and to verify construction accuracy. It is also easy to share data instantly with stakeholders via the cloud, smoothing communication between the field and the office. RTK adoption thus allows survey results to be immediately used for construction and quality control.

Q: What is LRTK? A: LRTK is the name of a new series of GNSS terminals that make conventional RTK surveying more user-friendly. Small, lightweight, and easy to handle, LRTK devices can be combined with smartphones so anyone can perform centimeter-level positioning easily. By making RTK—once requiring specialized equipment and knowledge—accessible, LRTK is attracting attention as a solution that can greatly improve surveying efficiency on construction sites.