Accurate Volumetric Survey

    When finished in 2018, the Orbital Highway in Doha, Qatar, will be a 14-lane road with five vehicle lanes and two dedicated truck lanes in each direction.

    There’s a construction boom taking place across Qatar, and Arcadis is helping make it possible. The global engineering consultancy, which has more than 27,000 employees based in 350 offices across the world, leads infrastructure development projects across Qatar, helping the country meet ambitious construction goals for the 2022 FIFA World Cup and for its 2030 National Vision.

    Arcadis recently had the opportunity to put drones to work on a project of a massive scale. Contract 2 of the Orbital Highway in the city of Doha, a 14-lane road with five vehicle lanes and two dedicated truck lanes going in each direction. The Orbital spans 46 kilometers in total, and construction will be finished in 2018.

    Arcadis was the lead designer of the Orbital, but its emerging drone operations presented a new business opportunity for this project. The client, Qatari Diar Vinci Construction (QDVC), a joint-venture company between Qatari Diar and Vinci Construction Grands Projets, wanted fast, accurate volumetric calculations for the earthwork spread throughout the entire roadway.

    “Our main deliverable for this project was volumetric calculations,” said Paul Kawuma, Innovation and Infrastructure BIM manager at Arcadis.

    Arcadis set ground control points throughout the highway and processed them in the cloud in Site Scan to increase the absolute accuracy of deliverables.

    Putting drone surveying to the test

    Arcadis is a pioneer of using drones for engineering purposes in Qatar, and the size of the site and specific goals of the project would be a perfect fit for a drone survey. However, to win the project to survey the whole highway, the firm first had to prove that it could get accurate volume calculations from drone surveys compared with traditional methods.

    Arcadis selected a three-acre area that was representative of the rest of the site and performed a test survey with both methods. The firm decided to use the 3DR Site Scan drone data platform, with its high-resolution 20.1MP Sony R10C and Autodesk integration, to bid on this project.

    “When we were preparing the business case and looking for a drone solution, Site Scan stood out compared to alternatives,” Kawuma said. “We liked how easy it was. We could trace the area to survey using the tablet, then the drone will fly itself and capture the images. We could then upload the images directly from the drone to the cloud — which plays a key role in streamlining the drone-to-data process — and they start processing into orthomosaics and other deliverables automatically. Even though we were just starting out with this new technology, it was easy to get into the workflow.”

    Ultimately, the traditional survey took three hours, while the drone survey took just 20 minutes. The drone captured substantially more data points too; while the traditional method captured 197 points, Site Scan was able to capture 1,539,964 points. This created a major difference in the level of detail.

    Because volume measurements were the initial focus, relative accuracy was most important, rather than the absolute location on Earth. That’s why Arcadis decided to compare data that Site Scan processed without the use of ground control points (GCPs), even though they would have helped improve accuracy even further. The sheer volume of points sampled by Site Scan also helped deliver more accurate earthwork volume quantities compared to a traditional survey (see Figure 1).

    After successfully demonstrating how much faster and more detailed drone surveys were, QDVC gave Arcadis the go-ahead to use Site Scan to capture the Orbital Highway.

    With certified drone operators and a fleet of Site Scan units, Arcadis started its work by setting GCPs to improve accuracy of deliverables. They flew automated nadir surveys with the drone, uploaded the photos to Site Scan Manager, then entered, tagged, and processed GCPs in the cloud. Cloud-based GCP processing is one of Site Scan’s newest features, and it’s far simpler and more efficient than alternative GCP workflows.

    In total, the Arcadis team created 34 unique drone maps — known as orthomosaics — using Site Scan’s multi-engine processing capabilities. They then exported the drone data into LAS and TIFF files and used them to generate raster data and their surfaces in Autodesk Civil 3D in order to produce volumetric calculations.

    The elevation model in Site Scan is helpful for understanding drainage
    and runoff areas.

    Key results

    Survey and measure earthworks 10 times faster — To perform a topographic survey of the test site with a drone, it only took the Arcadis team approximately 20 minutes in the field. Given that it would take three to four hours to perform a traditional survey of the same site, Arcadis proved that it can survey approximately 10 times faster with a drone.

    They were able to maintain this level of productivity throughout the entire Orbital project. By speeding up the surveying workflow with Site Scan, Arcadis was able to deliver volume calculations much faster than usual, helping their client keep the Orbital Highway project on schedule.

    “In the market we’re in, we’re realizing that drone surveys can be done 10 times faster than traditional topographic surveys,” said Liam Kirk, business director at Arcadis. “While we continue to work with licensed surveyors to collect control points and validate accuracy, the drone is a great addition to our platform.”

    Improved survey and volume measurement accuracy — Not only was Arcadis able to survey faster, but Site Scan helped create more accurate deliverables compared with a traditional survey.

    “The drone data was more accurate than a traditional survey when it comes to working on volumes because it catches more points,” Kawuma said. “This gave us a really dense point cloud compared to the 5-meter grid (separation of points) that we usually get with a traditional survey. This made our client far more comfortable deciding to go with the drone, and ultimately it delivered the results we needed. They were able to use this detailed data to make better, more informed decisions about the project, identify issues and risks quicker, and get a better understanding of future challenges they may face on the project.”

    Setting GCPs and processing them in the Site Scan cloud had a significant impact on absolute accuracy. It helped Arcadis georeference the orthomosaics with extreme accuracy and ensure they reflected reality as closely as possible.

    Figure 1: Site Scan delivered more accurate fill volume quantities because it captures more points than the traditional survey.

    Important project insights, all on one platform — Kawuma and his team also made use of Site Scan’s in-browser suite of engineering tools — such as measurements, contours, elevation models, and the cut-and-fill map — to better understand the topography of the Orbital project.

    “As Site Scan continues to add to its suite of tools for analyzing drone data, it’s really become like Civil 3D in the cloud,” Kawuma said. “For example, I find the elevation model helpful for understanding drainage and runoff areas. With Site Scan, we can get this type of information much faster and with far greater detail than a traditional survey.”

    After successfully using Site Scan on the Orbital Highway project, the Arcadis Qatar team is now actively scaling its drone operations and identifying new projects where Site Scan can make an impact.

    “When it comes to ease and efficiency,” Kirk said, “drones are taking surveying to a whole new level.”

    Hugh McFall is a marketing specialist with 3D Robotics (