Achieving Labor Reduction with GPS Surveying: Dramatic On-Site Efficiency Improvements

Field surveying work has traditionally required multiple people to operate heavy equipment. However, recent technological advances in GPS surveying have made it possible to reduce staffing and dramatically improve on-site efficiency. This article explains the challenges faced by conventional surveying and the latest GPS surveying solutions using RTK. It details how next-generation surveying methods—leveraging new technologies such as smartphone integration, cloud synchronization, and AR displays—are transforming field work and helping to alleviate labor shortages and boost productivity.

Challenges in Traditional Surveying

Traditional surveying work at civil engineering and construction sites has faced several major challenges. The first is the manpower issue. Conventional methods using total stations and levels required one person to operate the instrument while another held the staff or prism, meaning teams of at least two people were always necessary. Surveying also demands specialized knowledge and experience, and a shortage of skilled technicians can affect the progress of the entire site.

The second is the equipment issue. High-precision surveying required carrying tripods and heavy instruments across the site, and in mountainous areas or on large sites, transporting equipment alone was a significant burden. Setting up and installing instruments also took time, and adverse weather could make surveying difficult. This operation burden of heavy equipment contributed to the overall inefficiency of surveying tasks.

The third is the accuracy issue. Simple traditional surveying methods and general GNSS (GPS) devices suffered from insufficient measurement accuracy. Typical commercial GPS receivers or smartphone GPS can produce positioning errors on the order of a few meters, which does not meet the precision required for construction surveying (centimeter-level accuracy or better). As a result, precise measurements still relied on optical total stations for detailed angle and distance measurements. This created a dilemma between “GPS, which is easy but has large errors,” and “optical surveying, which is accurate but labor- and time-intensive,” making it difficult to achieve both efficiency and precision on site.

High-Precision GPS Surveying with RTK

One solution to these problems is Real Time Kinematic (RTK), a real-time satellite positioning correction technology. RTK exchanges error information between a reference receiver and a mobile unit (rover) to correct satellite positioning errors in real time, enabling high-precision positioning with errors on the order of a few centimeters. For example, while standard GPS can have errors approaching 10 m (32.8 ft), RTK can determine positions with horizontal accuracy of about 2-3 cm (0.8-1.2 in) and vertical accuracy of a few centimeters to at most a few tens of centimeters (a few inches to at most a few dozen inches). This level of precision is comparable to what used to be painstakingly measured by tape measures or total stations.

With the emergence of high-precision RTK positioning, GPS surveying has become practically accurate. What was once considered “GPS is too coarse to be used except for basic control points” can now be applied to precise layout of design lines and as-built control. Moreover, services such as Japan’s quasi-zenith satellite “Michibiki” are developing centimeter-level augmentation services like CLAS, enabling correction information even outside mobile communication coverage. These technological foundations make high-precision GPS surveying feasible even in locations where establishing a base station is difficult, such as mountainous landslide sites.

Easy Positioning and Records with Smartphone Connectivity

RTK-capable GPS surveying equipment now offers performance comparable to traditional optical instruments while achieving remarkable miniaturization and weight reduction. Particularly noteworthy are positioning devices that can be used with smartphones. A small device that fits in a pocket can be attached to a smartphone to instantly transform it into a high-precision GNSS receiver. There is no need to carry a dedicated controller or setup tripod, and the convenience of being able to complete a survey by simply walking the site with a smartphone in hand was unthinkable until recently.

Smartphone apps also improve usability. Traditional surveying instruments required button operations on dedicated controllers and complex settings, but smartphone-connected devices allow intuitive touch operation to start positioning and let you monitor your current location and survey points on a map as you work. The familiar smartphone UI makes these devices easier to use even for non-specialist surveyors, enabling site staff to perform surveying tasks themselves and contributing to labor savings—especially valuable when staff are limited.

Expanded Data Utilization with Cloud Sync

Smartphone-connected GPS surveying also innovates by enabling position data and survey results to be synchronized to the cloud in real time. Traditionally, using survey data involved bringing handwritten notes back to the office for drawing or analysis with dedicated software, and data transfer often required USB drives or format conversions, costing time.

Modern GPS surveying systems upload positioning results from the smartphone to the cloud on the spot, immediately digitizing the data. For example, coordinates of surveyed points can be instantly shared from the field with the office or clients, allowing the office to grasp site conditions remotely. Collaborative tasks such as overlaying results on topographic maps or drawings in the cloud and reviewing measurements become smooth. Even stakeholders without specialized software can view 3D data via shared links in a web browser, making cross-departmental and inter-company information sharing easy.

Because data are digitized and accumulated from the start, downstream workflows become seamless. Survey data can be imported directly into the design department’s BIM/CIM models for construction planning or used as as-built documentation, serving immediately as a foundation for digital construction. This prevents transcription errors and reduces data-processing time while improving accuracy.

Achieving Solo Surveying and Its Labor-Reduction Effects

By combining RTK-capable GPS surveying equipment with smartphones and cloud services, surveying tasks that once required several people can now be completed by a single person. For example, there have been reports of control point surveys that used to take two to three people half a day being completed by one person in a matter of several tens of minutes using an RTK-capable smartphone surveying device. Such efficiency gains are possible because high-precision equipment and digital integration greatly simplify both field work and post-processing.

Reducing personnel contributes to alleviating chronic shortages of skilled technicians. It prevents work delays caused by a lack of survey specialists and enables fewer staff to manage multiple sites. Reducing staff also directly lowers labor costs; if the labor cost of two to three people can be covered by one person, the savings can be redirected to other construction tasks or quality improvements. Given the construction industry’s widespread challenges of labor shortages and high costs, labor reduction through GPS surveying can be a powerful solution.

Additionally, the ability for one person to survey improves safety and mobility. In hazardous slopes or high-traffic sites, having one person complete surveys quickly reduces risk compared to multiple people working in the same area. Lighter equipment allows greater agility in poor footing, reducing the physical burden on workers. In this way, labor reduction creates a surveying environment that is kinder to both people and sites.

Intuitive On-Site Verification with AR

One new experience enabled by the fusion of GPS surveying and smartphones is the use of AR (augmented reality) displays. This technology overlays design or survey data onto real-world imagery on a smartphone or tablet screen. For instance, recently acquired point cloud data of the ground or structural models from design drawings can be projected onto the camera view for immediate verification. Information that used to be understood only through drawings or numbers can now be intuitively grasped by overlaying it onto the actual site view, facilitating mutual understanding among stakeholders.

AR displays are powerful for as-built inspections and design checks. You can visually confirm on-site whether a completed structure matches the design in position and elevation, or whether excavation and filling have been carried out within planned limits. Inspection tasks that used to involve surveying after construction and cross-checking with drawings can now be done in real time and visually with AR. High-precision AR without misalignment is achievable because RTK-derived absolute coordinates allow the smartphone to accurately position models.

Streamlining Piling Work and Navigation

On construction sites, staking out points for piling—known as "piling" or "layout"—has also been transformed by GPS surveying. Traditionally, positions were determined from drawings with tapes and transits, marking points and repeatedly re-measuring to ensure no deviation from the reference. GPS surveying systems with pile placement guidance allow you to specify the coordinates of the point to be surveyed, and the smartphone displays the direction and distance to that point in real time. Like a car navigation system guiding you to a destination, the worker simply follows the guidance to reach the installation point.

This coordinate navigation greatly improves the efficiency of piling work. There is no need for multiple people to call out positions from distant locations; a single person can accurately locate points. Even inexperienced workers can follow the navigation, reducing variability in work and contributing to consistent quality. Combined with AR, virtual piles or design lines can be overlaid on the screen for visual positioning, making pile placement even more intuitive. Pile placement navigation, taking advantage of high-precision GPS surveying, supports sites with speed and reliability that traditional methods could not offer.

3D Site Recording with Point Cloud Scanning

The combination of GPS surveying devices and smartphones is not only for measuring points but can also be used for 3D scanning to record terrain and structures. By using a smartphone camera or built-in LiDAR sensor while walking the site, you can capture photos and depth data to generate dense point cloud data. Because the point clouds are tagged with the high-precision position information obtained via RTK, they can be used directly as three-dimensional survey data in a global coordinate system.

For example, scanning a slope’s shape as a point cloud enables quick volumetric calculations and detection of deformations in a short time. Tasks that previously required measuring many points to create cross-sections and compute volumes can now be automated from point cloud data instantly. Point clouds can capture conditions in complex structures or confined spaces and obtain non-contact information from locations where people cannot enter, enabling safe and comprehensive as-built records. The 3D data obtained can be overlaid on drawings or BIM models to detect discrepancies from design or to deliver as-built deliverables.

Mobile point cloud scanning offers greater mobility and cost advantages compared with conventional terrestrial laser scanners. Without renting and installing large dedicated machines, a single smartphone can produce 3D records with sufficient accuracy. By scanning sites over time, construction progress can be managed three-dimensionally, and storing as-built data supports future maintenance.

Work Support through Geotagged Photos and Information Sharing

A useful feature of GPS surveying systems is geotagged photos. These are site photos taken with a smartphone camera that are tagged with high-precision position coordinates and orientation (camera direction). Each photographed survey point is linked with its photo and location, allowing photos to be reproduced on maps or 3D viewers in the cloud later. As a “visualization tool for the site,” this lets remote office staff concretely check site conditions.

Geotagged photos are expected to improve the efficiency of inspection and survey tasks. For road and bridge maintenance, for example, photos are indispensable for recording aging or identifying damage. If photos have location tags, the shooting position can be quickly identified on a map, making it easy to retake photos from the same angle as past images and compare changes. Combined with cloud sharing, site photos can be shared immediately among responsible personnel for discussion. Even if less-experienced staff take photos, remote assistance is possible, with veteran engineers at headquarters viewing photos and providing appropriate instructions.

The same cloud-sharing mechanism is also effective for distributing point cloud data and survey coordinates. With survey results shared in real time among all stakeholders, smooth workflows without rework are expected. When the site, design and construction management departments, and clients all reference the latest data, it helps prevent mistakes due to mismatched understanding. Thorough information sharing and history management also become a significant asset for future maintenance support. If as-built data and photos are accumulated in the cloud, past survey information can be referenced immediately when planning inspections or repairs, enabling accurate maintenance decisions.

Promoting Simple Surveying with LRTK to Support On-Site DX

The labor-reduction solutions introduced so far are key technologies supporting on-site DX (digital transformation) in construction. Among them, a product called “LRTK” has gained attention as a simple surveying tool that anyone can use with a smartphone. LRTK consists of a compact, lightweight RTK positioning device, a dedicated app, and cloud services; with a pocket-sized device and a smartphone, one person can perform high-precision surveys on site. Staff without specialized training can operate it intuitively, allowing companies to perform surveying work in-house that previously had to be outsourced.

By using LRTK, you can realize all-in-one functionality: RTK-level positioning, the convenience of smartphone integration, cloud-synced data sharing, and features such as AR display, pile-placement guidance, point cloud scanning, and geotagged photos. Initial and operating costs are also lower than acquiring large surveying equipment, making it easier to consider introduction even for small pilot projects. For engineers and managers struggling with on-site labor reduction and efficiency, adopting GPS surveying with such modern tools can bring dramatic operational improvements. Consider introducing a simple surveying system and accelerate on-site DX with cutting-edge technology.