Construction Efficiency and Quality Improvement Enabled by Slope Greening DX

Slope greening works are important civil engineering tasks that apply vegetation to cut and fill slopes to prevent soil erosion and improve scenery. These works are often carried out on steep slopes in mountainous areas and along roads, and the working environment is harsh, making efficient construction difficult. Traditional methods rely heavily on craftsmen’s experience and manual labor, requiring significant manpower and time and causing variability in quality. Against this backdrop, expectations are rising for Construction DX (digital transformation) as a means to simultaneously improve construction efficiency and ensure quality. In fact, with support from the Ministry of Land, Infrastructure, Transport and Tourism’s *i-Construction* initiative, the use of such digital technologies is becoming the new norm in civil engineering construction. By leveraging the latest 3D surveying technologies, AR (augmented reality), and high-precision GNSS positioning, among other digital tools, slope greening works can achieve labor savings, visualization of work, and reduction of mistakes, dramatically improving construction efficiency and accuracy. This article first organizes the challenges faced on slope greening sites, then explains key points for improving efficiency and quality through DX introduction. At the end of the article, as an example of a solution that can digitize everything from surveying to construction management, we introduce LRTK as a starting point for on-site DX.

On-site Challenges in Slope Greening Works

• Dangerous and inefficient surveying work: Surveying slopes on steep inclines requires workers to walk the slope and use tapes and staffs, which involves risks such as falls. Measuring each point takes time and manpower, making it difficult to grasp extensive terrain in a short time.

• Discrepancies between actual terrain and design: When site terrain differs from design drawings, the conventional approach required detailed surveying before construction and subsequent design revisions. Insufficient surveying accuracy or point density can lead to discoveries after completion that “the work is not as designed,” causing rework risks. Such discrepancies can lead to additional repair work or complaints.

• Burden of as-built confirmation and quality control: To confirm whether as-built features such as sprayed thickness or slope gradient meet design standards requires numerous measurements and photographic records. Traditionally, a limited number of measurement points were measured manually and on-site engineers performed pass/fail judgments and report creation, which was a heavy burden. Because measurements are taken only at points, there is also a risk of overlooking some defective areas.

• Labor shortage and skill succession issues: Slope work relies heavily on veteran specialized skills (rope high work, uniform spraying techniques, etc.), but aging of the workforce and a shortage of young workers are serious problems. Even if more workers are desired, safety concerns often limit the number of people who can work, increasing demand for labor-saving measures.

• Difficulty in on-site agreement and communication: When sharing the image of the finished state or the construction process with clients and stakeholders, drawings or verbal explanations alone can be hard to convey. Since slope greening places importance on the finished appearance, differences in recognition can lead to time-consuming rework or adjustments.

• Complexity of recordkeeping and reporting: Managing the huge number of photos and measurement data taken at each process step and creating as-built reports and drawings was conventionally done with paper ledgers or spreadsheet software and was inefficient. On busy sites, forgetting to take photos or other record omissions are common, and if records are not retained, quality cannot be proven and, in the worst case, rework or disputes may arise.

Construction Efficiency and Quality Improvement through DX Introduction

• Labor savings: By using DX technologies, tasks that relied on manual labor can be replaced by machines and digital tools, reducing the required workforce and working time. For example, the introduction of automatic measurement and data processing can allow surveying and inspections that once required multiple people to be completed by fewer people in less time.

• Visualization: Visualizing site conditions and design data with 3D models and AR makes previously unseen information intuitive. Projecting the finished image on-site or color-coding progress and deviations helps all stakeholders share the same understanding, reducing communication losses.

• Error prevention: Digital recording of measurements, automatic calculations, and cloud sharing can prevent human recording errors and missed measurements. Sensor-measured data are always objective, helping to suppress quality defects and rework caused by human error.

• Operational efficiency: Linking the flow from surveying to design, construction, inspection, and reporting digitally reduces waiting times and duplicated work. For example, if data acquired on-site are immediately analyzed and shared in the cloud, the traditional process of taking data back to the office for diagramming and reporting can be shortened. Real-time information sharing accelerates decision-making, contributing to overall schedule shortening and cost reduction.

• Improved safety: Labor savings and automation reduce the need for workers to enter hazardous areas. Remote measurement and real-time sharing raise the level of safety management. For example, surveying and inspection that used to be conducted on the slope can be done from a safe location, directly reducing worker risk.

Capturing Terrain as a Surface with Point Cloud Scans and Linking to Design

Among DX technologies, 3D point cloud scanning for terrain measurement is particularly effective. By acquiring 3D data of the entire slope with laser scanners or drone photogrammetry, elevation differences and surface irregularities can be captured as surfaces. There is no need to imagine between distant measurement points as in conventional methods; accurate terrain models, contours, and cross-sections can be freely generated from the acquired point cloud. This enables smooth coordination with design. For example, by importing the existing point cloud data into design software before construction, you can develop feasible design plans that fit the terrain. Also, by overlaying the as-built point cloud with the design 3D model, the finished condition can be checked at a glance. Point cloud data can also be used for volume calculations and slope area estimation, streamlining calculation of required greening materials and preparation of as-built inspection materials.

In recent years, the point cloud scanning methods themselves have become simpler. For large sites, drone photogrammetry is effective, while handheld laser scanners or LiDAR-equipped smartphones are useful for areas with dense trees or partial measurements. There are cases where attaching a high-precision GNSS receiver to a smartphone and walking allowed scanning of slopes about 30 m (98.4 ft) high in a matter of minutes. Compared to conventional surveying that required skill, these methods are easier for anyone to handle and allow measurements from safe locations. Introducing point cloud scanning enables thorough measurement of the entire slope, reducing “invisible deviations” and improving accuracy and reducing rework in both design and construction.

Visualizing the Finished Image with AR and Accelerating On-site Agreement

If the expected finished image on drawings can be overlaid onto the real landscape with AR, anyone can intuitively imagine the final outcome. Simply pointing a tablet or smartphone at the slope can bring up CG representations of the designed slope frames and vegetation layout on the slope, making it extremely useful during meetings with clients and site personnel. The finished appearance, which was hard to convey with words or 2D drawings, can be shared on the spot, speeding up detailed agreement formation. Also, visual checks with AR help prevent mistakes. For example, by projecting the design model on-site, you can check in advance whether it interferes with surrounding structures or whether sufficient space is secured for people to enter. After construction, overlaying the design model on the completed slope allows visual confirmation of subtle finishing differences that are hard to notice with the naked eye. Such AR utilization can reduce rework due to stakeholder recognition gaps and the “it’s not what I imagined” problem after completion.

Effectiveness of Smartphone Surveying and Navigation with High-Precision GNSS

High-precision GNSS refers to technologies (such as RTK positioning) that achieve centimeter-level accuracy (half-inch accuracy) by applying real-time corrections to satellite positioning errors. Recently, this technology has become smaller and lower in cost, making it possible to perform full-scale surveying simply by attaching an antenna receiver to a smartphone or tablet. Tasks that previously required total stations or experienced surveyors can now be done by recording point coordinates with a smartphone in hand or by guiding workers to specified positions, so anyone can easily carry out surveying and layout.

On slope greening sites, this smartphone surveying and navigation delivers significant benefits. For example, when marking boundary lines or planting positions for a designated slope area, instead of measuring with a tape while referring to paper drawings, you can simply walk in the direction indicated by the smartphone to reach the target point. Markers or arrows appear on the screen, showing “this is the design position” with centimeter-level accuracy, reducing marking mistakes and shortening work time. Measured point coordinate data are automatically saved and shared to the cloud, so you can digitize as-built conditions on the spot without worrying about forgotten or incorrect records. High-precision GNSS streamlines and reduces manpower for on-site positioning work, and the resulting reductions in time spent on dangerous slopes and in waiting for surveys also provide secondary safety benefits.

Labor Savings in As-built Inspections with Heatmap Comparisons and Cloud Reports

For inspections of slope greening works, confirming whether the post-construction slope shape matches the design and whether required thickness and gradients are met is essential. DX tools can dramatically improve the efficiency of this as-built confirmation. Particularly useful is the automatic comparison between design data and as-built point clouds. By overlaying the 3D design model with point clouds obtained from on-site scans, you can generate a heatmap that shows the degree of deviation with colors, allowing a quick grasp of the overall quality. For example, areas where the sprayed greening material thickness is insufficient or where there are protrusions or depressions relative to the design line are visualized in different colors, making it intuitive to judge whether errors are within allowable limits. This makes it easier to correct local defects that were previously easy to overlook, leading to more uniform quality.

Moreover, managing measurement data and inspection results in the cloud streamlines reporting tasks. If as-built tables and cross-sections are automatically created from point cloud data and saved in the cloud, inspectors can immediately review the contents from office PCs. There is no need to transfer data with paper forms or USB memory, and stakeholders can always share the latest information. Sharing inspection results with the client via the cloud allows on-the-spot pass/fail confirmation and corrective instructions, smoothing the handover process. By combining surface-based as-built comparison with heatmaps and cloud-based reporting, the labor and human errors associated with as-built inspections are greatly reduced, improving the reliability and speed of inspections.

DX Benefits for Disaster Recovery, Steep Slopes, and Infrastructure Maintenance

• Disaster recovery sites: When unexpected landslides or slope failures occur, DX technologies help assess damage and consider recovery methods. Even in dangerous, hard-to-access collapse sites, drone aerial photography and remote point cloud scanning can quickly acquire detailed terrain data. Sharing the situation immediately with relevant agencies via the cloud and using AR to project post-restoration shape images on-site for consensus building enable safer and faster recovery planning than conventional methods. These approaches are also effective in preventing secondary disasters because people do not need to approach unstable slopes right after an event.

• Construction on steep slopes: For particularly steep slope greening sites, manual work becomes more dangerous. DX introduction allows surveying and staking to be done safely from above, or remote construction by robots or automatic spraying equipment, enabling labor reduction and improved safety. There are reports that robotic spraying has increased construction speed by several times compared to conventional methods, showing that DX utilization can dramatically boost productivity. In addition, construction precision can be confirmed with real-time measurement data as work progresses, enabling efficient, quality-assured construction even on steep gradients.

• Infrastructure maintenance: For vegetated slopes along roads or around erosion control dams, DX is also effective for long-term post-construction maintenance. Recording and comparing surface changes with 3D scans during periodic inspections allows quantitative assessment of erosion progression and identification of areas needing repair. Accumulated point cloud data in the cloud can be used to analyze degradation trends or to consider repair plans with AR on-site, enabling more accurate and preventive maintenance than before. Continuously accumulating digital records shifts maintenance activities from reactive responses to preventive maintenance, contributing to long-term cost reductions.

Integrated Surveying, AR, Navigation, and Cloud DX with LRTK

Finally, a notable solution that enables consistent use of these DX technologies is LRTK. LRTK is a system consisting of a small RTK-GNSS receiver that attaches to a smartphone and a dedicated app, realizing point cloud surveying, AR display, coordinate navigation, and cloud integration in one device. Scanning a slope with a smartphone or tablet camera and LiDAR allows acquisition of high-precision 3D point clouds on-site and uploading them to the cloud. Acquired data are automatically analyzed, and heatmap comparisons with 3D models and generation of as-built reports are completed in the cloud. Also, the function to AR-display design coordinates on-site enables accurate marking of greening boundaries and construction positions by looking at the smartphone screen without paper drawings. LRTK digitally links the processes from surveying to construction, inspection, and reporting, making it a tool that can maximize the effects of on-site DX.

If you aim to improve the efficiency and quality of slope greening works, introducing such smart construction systems is one option. By utilizing LRTK, you can easily realize the DX benefits introduced above on a single platform. DX may seem large-scale, but a smartphone-centered system can be introduced even on small sites. Using it on-site allows you to immediately feel its labor-saving and efficiency effects. In an era of labor shortages and calls for work-style reform, smart construction management that incorporates the latest technologies directly contributes to improved productivity and safety on site. As a trigger for promoting your company’s on-site DX, please consider smartphone surveying and AR utilization with LRTK.