Labor and Efficiency Gains from Smartphone Surveying: Effects of Introducing LRTK

Today’s construction, civil engineering, and infrastructure sites are paying attention to a new surveying method called smartphone surveying. This surveying style, which leverages smartphones, has the potential to significantly reduce on-site workload and greatly improve operational efficiency. This article explains in detail the background for adopting smartphone surveying, its concrete effects, actual operational examples, and the positioning accuracy and usability provided by the key technology LRTK. Engineers and site managers in the construction and civil engineering industries who want to pursue labor savings and efficiency improvements should find this useful.

Background and Needs for Introducing Smartphone Surveying

Due to population decline, aging, and work-style reforms, the construction and civil engineering industries face serious labor shortages and a need to reconsider working styles. In particular, surveying work has traditionally required multiple specialized technicians, demanding significant time and cost for securing personnel and scheduling. Carrying heavy tripods and surveying instruments also places a physical burden on workers and raises safety concerns. Against this backdrop, there has been growing demand for technologies that enable surveying to be easier and faster.

At the same time, recent advances in ICT and DX have reached construction sites. With initiatives such as the Ministry of Land, Infrastructure, Transport and Tourism’s i-Construction promoting digitalization and efficiency of on-site tasks, attention turned to the ubiquitous smartphone. Smartphones are widely carried and have become highly capable devices; if they can be used for surveying, they promise dramatic labor savings that overturn conventional wisdom. In fact, smartphone camera and sensor technology has advanced dramatically, and the latest iPhone and Android devices even include LiDAR sensors capable of 3D scanning. These technological advances have opened the door to performing precise spatial measurements on a smartphone that were previously difficult.

However, standalone smartphone GPS positioning is coarse, on the order of several meters, and insufficient for professional surveying. High-precision positioning technologies such as RTK-GNSS (real-time kinematic positioning) and Japan’s QZSS “Michibiki” CLAS (centimeter-class positioning augmentation service) have therefore emerged. By combining these as small devices attached to smartphones, smartphones have evolved into centimeter-level (half-inch accuracy) surveying instruments. A representative solution is LRTK, developed by a venture from Tokyo Institute of Technology. When an LRTK device is attached to a smartphone, the RTK-GNSS receiver coordinates with the phone to achieve positioning accuracy ranging from several centimeters down to less than 1 cm (0.4 in). The arrival of smartphone surveying that can readily obtain high-precision position information is becoming a powerful ally for sites struggling with labor shortages.

Labor Savings and Efficiency Improvements Delivered by Smartphone Surveying

Introducing smartphone surveying significantly changes on-site work styles. Here we look concretely at how smartphone surveying reduces workload (labor savings) and improves overall operational efficiency.

Dramatic Reduction of Workload

In traditional surveying, it was often necessary for two-person teams or more to operate equipment—for example, one person holding a prism pole while another looks through a total station. With smartphone surveying, such manpower-intensive work is transformed. A single worker with a smartphone and a high-precision GNSS device can complete point measurement and recording. This reduces the effort of arranging personnel and can cut the manpower required for surveying by up to 50%.

Smartphone surveying equipment is also compact and lightweight, small enough to fit in a pocket. The LRTK device is compact, weighing only about 125g, with a thickness of about 13 mm (0.51 in), so it does not burden workers who move around the site. There is no need to carry and set up heavy tripods or survey instruments, greatly reducing the effort of equipment setup and teardown. Because there is no need to forcefully mount equipment in high or precarious locations, there are safety benefits as well. For example, when you need to measure a point near the top of a slope that cannot be reached by hand, you can use the smartphone’s camera and positioning capability to determine the location non-contact. Being able to obtain the necessary data while reducing the number of times people enter dangerous areas is a major labor-saving advantage.

Dramatic Improvement in Operational Efficiency

Smartphone surveying not only reduces manpower but also dramatically increases work speed and productivity. Previously, surveying required time for instrument setup and establishing references, and post-measurement data processing and drafting were time-consuming. Smartphone surveying dramatically simplifies these processes.

First, with point surveying using a smartphone and LRTK, coordinates can be obtained and saved instantly by simply tapping the smartphone screen on site. In addition to latitude, longitude, and elevation of the measured point, the app automatically converts to the local plane rectangular coordinate system and displays results immediately. There is no need to take notes on paper or convert coordinates later, so you can confirm the necessary values on the spot. Acquired data can be shared to the cloud with one touch, synchronizing information in real time between the site and the office. This reduces delays where work stops while waiting for survey results and allows stakeholders to move immediately to subsequent decisions and tasks.

Smartphone surveying-specific new functions also contribute to efficiency. For example, point cloud scanning using the smartphone’s LiDAR sensor enables 3D measurement of wide-area terrain and structures in a short time. Complex terrain that would have taken days to measure many points using conventional methods can be completed in minutes by scanning with a smartphone. Because cross-sections and surface irregularities can be automatically analyzed from the acquired point cloud data, the speed of understanding existing conditions and managing as-built quantities improves dramatically. In addition, you can immediately overlay acquired 3D point clouds with design data to calculate fill volumes or check as-built discrepancies. Processes that previously required office CAD drafting and comparison with design drawings after surveying can now be completed end-to-end on site.

Smartphone surveying is also highly compatible with AR (augmented reality) technology and contributes to on-site consensus building and verification. For example, by projecting the design model onto the real scenery through the LRTK app’s AR function, stakeholders can share the finished image on site before construction, reducing communication loss and preventing rework. Including these added values, smartphone surveying is a powerful tool for overall site efficiency improvement.

Examples of Smartphone Surveying Use on Site

What changes actually occur at sites that have introduced smartphone surveying? Here we present two cases—civil construction sites and disaster response sites—to show the effects.

Example of Implementation at a Civil Construction Site

At a certain road construction site, LRTK-based smartphone surveying was trialed. Previously, a specialized surveying team would visit weekly for as-built management and stakeout (layout) work. Because surveying could only be done at limited opportunities, errors or mismatches with actual conditions could not be corrected immediately, sometimes affecting construction progress.

After introducing smartphone surveying, site staff themselves could perform surveys immediately as needed. For example, whether confirming the depth of buried utilities or conducting interim inspections, they could take out a smartphone and measure and record on the spot. This allowed flexible responses without waiting for an external surveying team, shortening construction time and enabling flexible schedule management. One site supervisor commented, “Because we can measure whenever we think of it, the site’s PDCA cycle has become markedly faster.”

Moreover, because daily as-built checks became easier with smartphone surveying, the frequency and accuracy of quality control improved. By having responsible personnel measure construction points before or after daily briefings and share data to the cloud, the office can also grasp progress in real time. As a result, early detection of rework and mistakes leads to improved overall productivity.

Example of Use in Disaster Sites

Smartphone surveying is also powerful for infrastructure inspection and disaster response. In the 2023 Noto Peninsula earthquake-affected area, communications infrastructure was severed and it was impossible to bring in large surveying equipment. In that situation, engineers on emergency surveys used smartphones equipped with LRTK to record and share damage conditions. LRTK can receive CLAS signals from Japan’s QZSS directly even outside internet coverage, enabling high-precision positioning. Therefore, even in mountainous areas with no mobile signal, centimeter-level (half-inch accuracy) surveying enabled accurate acquisition of positional information for damaged sites.

The survey team automatically recorded the position coordinates and shooting direction measured by LRTK for photos of damaged structures taken with the smartphone. These data were later collectively shared via the cloud once communications were restored and quickly delivered to relevant agencies. Whereas conventional procedures would have required making notes on paper maps and later entering data into a PC, accurate digital records were completed solely by on-site work. A respondent reported, “We could get all necessary information with a single small device. We did not need to work long hours in a site with secondary disaster risk, so safety was improved,” demonstrating the usefulness of smartphone surveying in disaster response.

High-Precision Positioning and Easy Operation with LRTK

The core technology enabling smartphone surveying is the aforementioned LRTK. By utilizing LRTK, smartphones can perform at levels comparable to conventional dedicated surveying instruments. Note the key features of positioning accuracy and usability.

Centimeter-Level Positioning Accuracy

Using the RTK method based on GNSS (satellite positioning systems), LRTK reduces smartphone positioning errors to within a few centimeters. While typical smartphone GPS has errors of several meters, LRTK uses correction information from base stations and CLAS signals from Michibiki satellites to achieve practical accuracy of approximately 1–2 cm (0.4–0.8 in). By remaining stationary and averaging data over a certain period, cases achieving sub-1 cm (0.4 in) accuracy are also possible. This level of precision approaches that of conventional GNSS receivers and total stations, and is sufficient for on-site layout and as-built checks.

Another notable feature is that LRTK can maintain high precision even outside communication coverage. In mountainous or underground locations where mobile networks do not reach, the LRTK device can directly receive Michibiki augmentation signals and continue high-precision positioning in real time. This enables surveying in environments that were previously impossible, greatly reducing constraints on work areas.

Simple Operation for Anyone

Despite its high performance, LRTK operation is very simple. A dedicated small receiver is attached to the smartphone with one touch, then the app is launched and you simply press a button on the screen at the location you want to measure. The process from start of positioning to result display is smooth, and it is designed so that on-site staff without specialized knowledge can operate it intuitively. Bluetooth connection links the smartphone and device, eliminating cumbersome cables, and the device has a built-in battery for long operation.

The LRTK app also includes useful on-site features. For example, it automatically records sequential numbers and timestamps for each survey point and allows notes to be added. Even when measuring multiple points consecutively, you can add new points with one tap, enabling uninterrupted work. Measurement data are plotted directly on a map and functions such as distance and height difference between two points are completed within the app. Not only are paper notebooks and calculators unnecessary, but measured data are immediately backed up to the cloud, eliminating concerns about data loss.

In this way, LRTK is designed as “a surveying instrument anyone can use with a smartphone.” By becoming a one-person, one-device tool that each field worker can casually take out of their pocket to measure, the barrier to surveying work has dramatically lowered.

Changes to On-Site Operations from Introducing Smartphone Surveying

The introduction of smartphone surveying and LRTK brings various changes to daily site operations. Below are comparisons of how site work changes before and after introduction.

• Change in personnel structure: Before introduction, multiple people including specialized staff were assigned for each survey. After introduction, surveying is generally completed by one person. This allows other workers to be assigned to different tasks and improves the overall utilization efficiency of the team.

• Change in work speed: Previously, surveying could take half a day to several days for equipment setup and observation. With smartphone surveying, many cases are completed in minutes to hours. Especially small measurements or supplementary checks can be done immediately, greatly reducing downtime due to waiting.

• Change in data processing: Recording in paper notebooks, photo organizing, and later drafting of drawings in the office are replaced by real-time digitalization on site after introduction. Because survey information is immediately shared via the cloud, time spent preparing reports and drafting drawings is also shortened.

• Change in communication: Before introduction, sharing survey results took time and sometimes caused misunderstandings. After introduction, everyone can instantly check the same map or model on the cloud, smoothing communication among site, design, and clients. As a result, rework reduction and thorough safety checks have positive effects on overall site management.

By adopting smartphone surveying, site workflows themselves are being reexamined and changing toward faster, less error-prone operations.

Quantitative Evaluation of Introduction Effects

Finally, we summarize the quantitative effects obtained from smartphone surveying (with LRTK introduction). Demonstrations and case studies on site report the following numerical effects.

• Positioning accuracy: High-precision surveying with errors within about 1 cm (0.4 in) is possible (improvement of several hundred times compared to conventional smartphone GPS).

• Personnel reduction: Labor required for surveying can be reduced by 50% (achieving one-person surveying instead of two).

• Work time: On-site surveying time is dramatically shortened. In some cases, more than 90% time reduction compared to conventional methods has been achieved (for example, routine on-site surveying reduced to less than one-tenth).

• Data processing time: Digital automation of survey records reduces the time required for report preparation and drafting to half or less.

• Productivity improvement: Due to the above effects, total productivity of surveying-related tasks is expected to increase by dozens of percent or more. Increasing survey frequency does not increase workload, enabling thorough quality control.

Quantitative effects vary depending on site conditions, but many case studies confirm that smartphone surveying provides overwhelming efficiency and labor savings compared to traditional methods.

Conclusion: Site Innovation with Smartphone Surveying Starting from LRTK

The advent of smartphone surveying brings a fresh wind to construction, civil engineering, and infrastructure management sites. By combining smartphones with small devices, anyone can perform advanced surveying, contributing to solving labor shortages and promoting work-style reform. As we have seen from concrete benefits in labor savings and efficiency, smartphone surveying greatly contributes to improving site productivity and ensuring safety.

Among technologies, LRTK stands out as a key technology enabling smartphone surveying, notable for its high precision and ease of use. Because it can turn a handheld smartphone into a surveying instrument without preparing dedicated equipment, initial adoption barriers are low and site penetration is likely to progress. Companies have already begun deploying LRTK devices on a one-per-person basis to dramatically improve work efficiency.

Going forward, smartphone surveying is expected to spread further as a trump card for on-site DX. If your workplace faces challenges in reducing labor or speeding up surveying tasks, consider introducing simple surveying with LRTK. Start easily with smartphone surveying and open up the future of your site.