Land improvement as-built management in the cloud! Instant verification with design data using LRTK

1. Importance and challenges of as-built management in land improvement works

In land improvement projects (agricultural civil engineering), as-built management—confirming that structures such as irrigation channels and fields have been constructed according to design—is extremely important. As-built management refers to the process of measuring the shapes and dimensions of completed structures or prepared land to verify they match the design, and recording and managing those results. Especially in public land improvement works, it is necessary to demonstrate compliance with standards set by the client (municipalities or land improvement associations), and it is an indispensable step for ensuring quality and calculating work quantities. Proper as-built management improves construction accuracy and reduces rework. As a result, it also helps build trust with the client.

On the other hand, traditional as-built management has many challenges and has become a bottleneck on site. Common concerns include surveying taking too much effort and manpower, and data processing taking time so the situation cannot be grasped in real time. This article organizes the importance of as-built management and the challenges faced in land improvement works, and introduces solutions using cloud and digital technologies. We focus in particular on a next-generation method that allows a single person to complete as-built management using “smartphone surveying,” which combines a smartphone and high-precision GNSS. The key to this is our company’s device LRTK. Utilizing the cloud and LRTK enables instant verification against design data, initiating a revolution in as-built management that overturns conventional on-site practices.

2. Traditional surveying and recording methods and their limits (manpower, time, accuracy)

As-built management in civil engineering, including land improvement, has long depended on manual surveying. For example, measuring the bottom or width of an irrigation channel with a tape, checking field elevations with a leveling staff (rod) and an automatic level, or measuring the alignment of farm roads with a total station (TS). Typically, heights and positions are measured from reference points at each construction location, and the results are compiled into paper as-built management charts and photo ledgers for reporting. In large-scale field improvement projects, the number of observation points (survey points) becomes enormous, and surveying teams must inspect hundreds of locations. Such traditional methods have the following constraints and inefficiencies:

• Heavy manpower and labor burden: Surveying work is usually done by teams of two, with one person operating the instrument and the other holding a staff or prism at the survey point. Including transporting and setting up heavy equipment, surveying wide farmland requires considerable effort. With labor shortages worsening, such manpower-intensive approaches have limits.

• Time and efficiency issues: The sequence of surveying → drawing preparation → quantity calculation → as-built confirmation can take several days. Because measurements are taken on site and then processed into drawings and quantities at the office, discovery of defects is often delayed. Meanwhile, other processes may be put on hold, creating inefficiencies and affecting the schedule.

• High equipment costs: High-precision total stations and GNSS surveying equipment are expensive, and it is not easy for small and medium contractors to procure them. Outsourcing to specialized surveyors raises costs, making frequent as-built surveys difficult.

• Errors and human mistakes: Manual recording and transcription into Excel inevitably carry a risk of mistakes. Missing survey points or miswriting numbers can degrade accuracy due to analogue procedures. Measuring only a limited number of points risks overlooking construction defects in unmeasured locations.

• Dependence on specialized skills: Operating surveying equipment requires skilled technicians, and if there are few personnel within a company, “waiting for surveying” time can occur. When the person in charge is absent, on-site immediate measurement cannot be performed, reducing flexibility in progress.

As described above, traditional as-built management is manpower- and time-intensive and lacks responsiveness, so improving productivity has been a major challenge. The same applies to land improvement sites where surveying delays can affect overall progress amid constraints such as weather and water management. To solve these issues, national and local governments have recently promoted DX (digital transformation) in the construction field, and new technologies are beginning to be introduced in surveying and construction management.

3. Visualizing as-built conditions through cloud and digitalization

By leveraging the latest technologies, as-built management can be dramatically streamlined through cloud and digital capabilities. The Ministry of Land, Infrastructure, Transport and Tourism’s “i-Construction” and the Ministry of Agriculture, Forestry and Fisheries’ promotion of “information technology-based construction” have accelerated the trend of reducing labor in as-built measurement and recording via digital tools. Examples of advanced surveying and management technologies appearing on sites include:

• 3D laser scanners and drone surveying: Terrestrial laser scanners mounted on tripods and photogrammetry by drones acquire the post-construction terrain as detailed point cloud data, allowing areal understanding of as-built conditions. They are powerful for capturing conditions in hazardous areas where people cannot enter and for grasping the shape of extensive fields. However, the equipment is large and expensive and data processing requires expertise, making adoption challenging for small-scale contractors.

• RTK-GNSS surveying: RTK surveying devices, which obtain centimeter-level accuracy by applying real-time corrections to satellite positioning, have long been used for machine guidance on construction equipment and reference point surveys. Recently, efforts to apply this to as-built management—quickly collecting survey points across wide fields and long waterways by a single person—have begun in various places. Historically, specialized and expensive GNSS receivers and local base stations were required, but the use of network correction services over the internet and Japan’s quasi-zenith satellite MICHIBIKI has made easier operation increasingly possible.

• Use of ICT construction equipment and AR technology: Movements to introduce automated control of construction equipment (machine control) and AR (augmented reality) into construction management are advancing. For example, in as-built management, technologies have emerged that overlay design 3D data and on-site as-built data in the cloud and automatically generate color-coded error displays as heat maps. These can be downloaded to tablets or smartphones and displayed in AR on site, enabling intuitive identification of defective locations.

Such digital visualization of as-built conditions makes it easier to detect even small deviations that were previously overlooked. With the cloud, as-built data obtained on site (such as survey point coordinates or point cloud models) can be uploaded immediately and shared with the office or the client. Compared with the traditional practice of taking paper drawings back for checking, the major advantage is being able to visualize site conditions in real time.

4. Point cloud data and design comparison: deviations visible at a glance

If as-built data and design data are compared in the cloud, construction quality can be judged at a glance. Specifically, the 3D model from the design or prescribed shape data is overlaid with the point cloud data or survey coordinates collected on site, and the discrepancies between the two are automatically calculated. By color-coding those differences (creating a heat map), one can visually identify where the site is built higher than the design or where excavation is insufficient and the surface is lower. For example, setting thresholds so areas more than +5 cm higher are red and areas more than −5 cm lower are blue makes it immediately clear which locations are out of tolerance.

If the point cloud data are obtained with positional coordinates, aligning (registering) them with the design data can be completed with the push of a button. Heat maps of as-built conditions are easy to interpret even without expert knowledge, allowing both site personnel and clients to share a common “visible” dataset. Whereas previously workers had to scan drawings to find nonconforming areas, heat maps allow intuitive detection of deviations.

As a more advanced application, it is becoming possible to take this heat map to the field and display it in AR. By viewing the actual structure through a smartphone or tablet screen with the heat map overlaid, you can identify on the spot “at which point” and “to what extent” construction errors exist. This enables immediate marking of areas requiring correction and swift feedback to construction teams, speeding up rework responses on site. Point cloud × design comparison is transforming as-built management from mere numerical checks into a process that can be visually understood and acted upon promptly.

5. Value of real-time construction verification using high-precision positioning

Another key technology for instant as-built confirmation is high-precision GNSS positioning (RTK surveying). With RTK-GNSS, centimeter-level positioning accuracy is possible even in outdoor fields and along waterways, allowing accurate on-the-spot measurement of structures immediately after construction. This makes real-time as-built verification alongside construction realistic.

For example, in field leveling work, a single person can measure heights at various locations immediately after finishing, send the data to the cloud, and compare it with design elevations. If local areas with insufficient fill are found, the machine operator can be instructed to add fill right away, enabling quick corrective action. Rework that would previously have been discovered by later re-surveys can be resolved on the same day.

Real-time positioning also excels at stake-out and as-built guidance. A GNSS-linked tablet can display stake positions and elevations on site based on design coordinates, improving efficiency in setting out batter boards and aligning pipelines. In land improvement sites where maintaining straight lines and gradients over long distances is necessary, high-precision GNSS helps maintain correct lines continuously.

Importantly, these high-precision positioning and cloud-linked systems are becoming usable by non-specialist surveyors. If site agents and construction managers can perform surveying and verification with a smartphone in hand, situations where the site is halted “waiting for the survey team’s results” can be avoided. An environment that enables real-time as-built checking directly contributes not only to quality assurance but also to overall site productivity.

6. Use cases and outcomes for waterways, field improvements, and farm roads

Cloud as-built management and RTK surveying are effective across various work types in land improvement. Below are typical use cases and expected outcomes for major structures.

• Irrigation and drainage channels: Scanning cross-sectional shapes and gradients of concrete or earthen channels as point clouds allows as-built checking along the entire length. Local bottom sags or wall height errors can be identified via color-coded heat maps, detecting defects that conventional cross-section measurements every tens of meters might miss. For deep U-shaped channels or buried drainage, scanning from above without entering the channel enables as-built confirmation and improves safety.

• Field improvement: In leveled, partitioned fields, areally checking deviations from reference elevations ensures a highly even finish. Walking the field alone with RTK positioning or LiDAR scanning can obtain hundreds of elevation points in a short time, and generate a heat map of bumps and hollows that same day. Because the results are automatically used for earthwork volume calculations in the cloud, early recognition of needed fill volumes and arrangements for additional materials, as well as correction of excess fill, enable quick schedule adjustments.

• Farm roads and agricultural roads: Digital as-built management is useful for controlling roadbed heights and cross slopes of farm roads. A single person can continuously measure whether the longitudinal slope of a long straight road matches the plan and whether cross-fall in curves is appropriate. Overlaying as-built alignments with design data in the cloud makes irregularities and undulations immediately apparent. Measuring precisely at the subgrade and base stages before paving allows micro-adjustments before irreversible paving operations, contributing to high-quality finishes.

• Pipelines and buried drainage: For buried pipeline work, it is essential to construct pipes with accurate slope and depth. Traditionally, heights between manholes were checked by leveling after installation, but with RTK surveying, the pipe invert and manhole installation elevations can be checked in real time before backfilling. For extensive buried drainage pipe networks, taking position coordinates with a smartphone immediately after laying leaves an accurate installation map in the cloud even after backfilling. That data can be referenced during future maintenance and helps locate excavation points. During construction, one person can measure wide-area pipe positions, preventing work stoppages and preemptively avoiding errors such as misrouting.

As described above, as-built management using the cloud and LRTK improves both quality and efficiency for all major work types in land improvement. The advantages of areal and spatial data management are particularly significant in agricultural civil engineering sites, where terrain tends to be wide and complex.

7. What is LRTK? An overview of simple smartphone surveying

Here we introduce LRTK in detail, which supports next-generation as-built management. LRTK is an ultra-compact RTK-GNSS receiver device that attaches to a smartphone. It weighs about 125 g and is about 1.3 cm (0.5 in) thick, fitting in a pocket; it houses a satellite antenna and battery. It is attached to the back of an iPhone or iPad via a dedicated smartphone case (or magnetic attachment) and connects via Bluetooth. There are no troublesome cables, and a full charge provides about 8 hours of continuous positioning, covering a day’s work.

As for positioning performance, LRTK supports multi-GNSS such as GPS, GLONASS, Galileo, and MICHIBIKI, and is equipped with a high-performance chip receiving multiple frequencies such as L1/L2/L5. By receiving network RTK (Ntrip) correction information via the smartphone, it achieves surveying-class accuracy of approximately ±1–2 cm (±0.4–0.8 in) horizontally and ±2–3 cm (±0.8–1.2 in) vertically. Furthermore, it is compatible with Japan’s quasi-zenith satellite MICHIBIKI’s centimeter-level positioning augmentation service (CLAS), allowing continued high-precision positioning using satellite augmentation signals alone even in mountainous areas with poor cellular reception.

A dedicated surveying app is installed on the smartphone equipped with the LRTK device. This LRTK app enables all functions required for as-built management—positioning, point cloud scanning, photography, AR display, and more—on a single device. For example, tapping a button at a point records the latitude, longitude, and elevation at that moment along with the date and time. Conversion to Japan’s plane rectangular coordinate system and automatic calculation of geoid height are performed, so coordinate transformations that previously required manual calculation or separate PC processing are completed instantly. The app also uses the iPhone’s built-in LiDAR sensor and camera to scan surrounding structures as 3D point clouds. Acquired point clouds and survey point data can be synced to the LRTK Cloud with one tap and shared immediately with colleagues in the office or inspection personnel. Using AR functionality, design models can be overlaid on site imagery and the aforementioned heat maps can be checked in the field. In short, with LRTK, you can complete “measure, record, compare, and share” with a single smartphone without carrying expensive dedicated surveying equipment or drawing ledgers.

8. Connecting design, construction, and inspection: on-site effects of cloud as-built management

Introducing LRTK and the cloud links design, construction, and inspection processes directly via data. Concretely, the client’s design drawings and 3D models can be uploaded to the cloud in advance, allowing contractors to overlay and verify as-built data collected on site on the same platform. This enables autonomous quality control, where contractors themselves continuously check as-built achievement status as they proceed.

Because as-built data in the cloud can be shared in real time with clients and inspectors, pre-inspection checks and corrective discussions can take place early as needed. Clients can also feel confident entering inspections if evidence data of as-built conditions is accumulated in the cloud, and that data can be used directly for preparing inspection documents. In fact, the LRTK Cloud is being developed to automatically generate reports from as-built heat maps and measurement point lists and output them with one click. This greatly reduces the work that site supervisors previously spent creating as-built charts and photo ledgers.

Moreover, integrating design, construction, and inspection information in the cloud enables smooth, data-driven communication with the client. Details that were hard to convey on paper are easier to share with 3D data, reducing discrepancies in understanding about as-built conditions. As a result, consensus-building about “what to correct” or “whether this finish meets standards” becomes faster, contributing to schedule shortening and preventing unnecessary rework. Cloud as-built management connects the site and office and contractors and clients seamlessly through data, raising the productivity and reliability of the entire project.

9. Future outlook for land improvement sites and data-driven as-built management

Digital technology–based as-built management will greatly change the future of land improvement sites. With high-precision surveying possible through the simple combination of smartphone + cloud, ICT construction—which was once limited to large projects or pioneering companies—will become common in general land improvement projects. In the future, as-built management may be performed almost concurrently with construction, making the old practice of hurried post-completion re-surveys a thing of the past.

Additionally, as as-built and quality data accumulate in the cloud, data-driven construction management and feedback will become possible. For example, AI could analyze accumulated data to predict trends in construction accuracy or to forecast frequently occurring defects in advance. Construction management engineers will be freed from the physically demanding surveying tasks and can focus on higher value-added work such as optimizing plans and considering measures to improve quality based on data. Although land improvement has traditionally been seen as heavy on analogue work, riding the DX wave will evolve sites into smarter environments with dramatically improved safety, quality, and efficiency.

With support from national and local governments, 3D data–based as-built management is expected to become the industry standard. Accumulating experience by introducing digital technology on-site now will lead to future competitiveness. Data-driven as-built management is not a passing trend but will become an indispensable foundation for future land improvement sites.

10. Start small: recommended on-site introduction of LRTK

Hearing “cutting-edge cloud as-built management” might conjure images of large-scale implementation, but with LRTK you can start easily from your smartphone. Initial setup is simple: attach the LRTK device to a supported iPhone and install the app. There is no need to procure expensive dedicated equipment, and trial implementation in part of a site is straightforward.

As the saying goes, seeing is believing, so we recommend trying as-built surveying with LRTK first on a small field or a section of a waterway. Once you use it, you will be surprised at how easily surveying results are uploaded to the cloud and displayed in color. After experiencing this efficiency and accuracy once, you will likely not want to return to the old ways. Site staff have commented that “it’s overwhelmingly easier than managing with paper drawings and tape measures” and “daily progress management is visible in numbers, making meetings with clients smoother.”

DX in land improvement does not require replacing everything overnight. The important thing is to start digitalizing where you can. LRTK’s simple surveying is an ideal first step. Please experience the benefits of cloud as-built management on your site and accumulate know-how for future full-scale deployment. You will surely realize the transformative power of LRTK, which you can start using with a single smartphone.