Comparing RTK GPS and Conventional GPS Surveying: Choosing the Optimal Positioning Method by Cost, Accuracy, and Operational Efficiency

The evolution of GPS surveying technology has greatly expanded the options for positioning methods available in the field. However, as options have increased, it has become more difficult to determine which balance of cost, accuracy, and work efficiency should be prioritized. In this article, we compare RTK GPS surveying and conventional GPS surveying (including static and kinematic surveying) from three perspectives and present optimal selection criteria based on actual field conditions.

Table of Contents

• Overview of conventional GPS surveying methods

• Features and strengths of RTK GPS surveying

• Accuracy comparison: How many centimeters of error does each method have?

• Cost comparison: Initial investment and operating costs

• Work efficiency comparison: Effects on time and personnel

• Which method is suitable for which sites

• Field adoption of RTK positioning enabled by LRTK

Overview of Conventional GPS Surveying Methods

"Traditional GPS surveying" can be broadly divided into three types: static surveying (static survey), simple kinematic surveying (kinematic survey), and single-point positioning.

Static surveying is a method for obtaining high-precision coordinates by installing receivers at multiple observation points and analyzing long-duration observation data of 1–2 hours or more in post-processing (ポストプロセッシング). It is used for tasks such as geodetic control surveys and boundary determination surveys, where mm- to cm-level accuracy (mm (0.04 in) to cm (0.4 in) level; cm level accuracy (half-inch accuracy)) is required. Because the site cannot be left during observations, operational efficiency is low, but the accuracy is very high.

Kinematic surveying (PPK: Post-Processing Kinematic) is a method that records satellite data while moving and later analyzes it together with reference-station data. A typical use is in combination with flight logs from drone surveys, and it has the advantage of not requiring real-time corrections.

Standalone positioning (standalone GPS) is a simple method that displays position in real time, but its accuracy is about 3-5 m (9.8-16.4 ft).

Features and Advantages of RTK GPS Surveying

RTK surveying receives correction data in real time and can obtain a FIX solution on the spot (centimeter-level accuracy (half-inch accuracy)). While static surveying "achieves accuracy through post-processing," the main difference is that RTK surveying "allows accuracy to be confirmed in real time on site."

This makes it possible to detect and correct measurement errors and coordinate mistakes on the spot, greatly reducing the risk of having to re-survey. In addition, the measurement time per point is short—ranging from a few seconds to several tens of seconds—making it suitable for repetitive work such as multi-point measurements over wide areas, staking out, and boundary verification.

Using network RTK eliminates the need to set up a base station, saving time on survey preparation. The ability to start measurements immediately upon arriving on site is an especially important advantage for sites with short construction periods.

Accuracy comparison: What is the error in centimeters for each method?

We compare the accuracy of surveying methods. The accuracy of static surveying (post-processing) is approximately 5-10 mm (0.20-0.39 in) horizontally and 10-20 mm (0.39-0.79 in) vertically, and it boasts the highest accuracy among GPS surveying methods. However, it requires long observation times, and analysis is necessary after fieldwork is completed.

The accuracy of PPK kinematic surveying is 1-3 cm (0.4-1.2 in) horizontally and 2-5 cm (0.8-2.0 in) vertically, achieving accuracy equivalent to or close to RTK. However, accuracy cannot be verified on site, and the cost of re-surveying is high if problems are discovered.

RTK positioning accuracy is 1-2 cm (0.4-0.8 in) horizontally and 2-3 cm (0.8-1.2 in) vertically, and because measurements can be taken while confirming a FIX solution, immediate verification of data quality is possible. Because network communication is required, it cannot be used in locations without signal.

The accuracy of standalone GPS positioning is horizontal 3–5 m (9.8–16.4 ft), and can exceed 10 m (over 32.8 ft) in the worst case, making it insufficient for surveying and construction management.

From a practical on-site perspective, RTK positioning is currently the mainstream approach as a method that satisfies the three requirements of accuracy, real-time performance, and operational efficiency at a high level.

Cost Comparison: Initial Investment and Operating Costs

The cost of GPS surveying equipment varies greatly depending on the method. A conventional receiver for static surveying costs about 500,000–2,000,000 yen per unit, and including software further increases the cost. Because multiple units are required to observe two or more points, the initial investment is high.

A single-base RTK system package (base station, rover, and radio) typically costs around ¥600,000–¥2,500,000, and although the standalone purchase cost remains high, it can be recouped through improved work efficiency after deployment compared with static surveying.

With network RTK, you only need to purchase the rover (about ¥200,000–¥1,000,000), and a correction service fee is charged monthly or annually. Because there is no need to install or manage reference stations, long-term operating costs can be kept down.

Smartphone-linked RTK modules that have appeared in recent years can be purchased for as little as tens of thousands of yen, and because they do not require a dedicated controller, additional costs are minimal. Their price level makes them easy to roll out to on-site staff who are not surveying specialists, and they are a realistic option for small-scale businesses and multi-site deployments.

Comparison of Work Efficiency: Impact on Time and Personnel

From the perspective of work efficiency, there are clear differences among the methods. Static surveying requires observations of 1–2 hours or more per point, and measuring multiple points in a single day requires a significant amount of equipment and personnel. Since post-processing time is also required, the total working time increases.

RTK surveying can measure a point in a few seconds to about one minute, allowing coordinates to be checked immediately on site. A single operator can handle several dozen to several hundred points per day, dramatically improving personnel efficiency. With network RTK, there is no need to set up a base station, so measurements can begin immediately upon arrival at the site.

Data management efficiency is also improved. Data recorded by the RTK receiver can be exported in digital formats such as CSV and Shapefile, making it easy to import into CAD software and GIS systems.

Which method is appropriate for which site

Static surveying remains an effective option for control point surveying, route surveying, and boundary determination surveying that require high accuracy. On the other hand, RTK surveying is optimal for tasks that require real-time position verification on site, such as setting out, stake driving, site condition checks, measurement of aerial markers for drone flights, infrastructure inspections, and completion inspections.

When the budget is limited and the objective is to obtain only a rough sense of location rather than high accuracy, standalone GPS positioning can be adequate in some cases. However, for location information related to on-site safety management or construction quality, insufficient accuracy can lead to serious problems, so reliance on standalone positioning should be avoided.

Enabling field deployment of RTK positioning with LRTK

The LRTK (iPhone-mounted GNSS high-precision positioning device) is a compact device that enables network RTK positioning simply by attaching it to an iPhone. Compared with conventional dedicated RTK equipment, it has a lower deployment cost and can be operated intuitively from an iPhone app.

It responds to the demand for staff who are not surveying specialists—such as those in construction management, inspection, and investigations—to handle RTK-precision positioning information on-site, contributing to organization-wide digitalization and the promotion of data utilization. When introducing RTK surveying that optimizes cost, accuracy, and operational efficiency, LRTK is a practical and economical option.

By accurately comparing RTK GPS surveying and conventional GPS surveying, choosing the method that best matches the site's required accuracy, budget, and working style is the quickest way to simultaneously improve on-site productivity and quality.