C+S May 2021 Vol. 7 Issue 5 (web)

“We were so impressed,” says Travis. “Surveys of stone and dirt, stockpiles that have a lot of differential in photos, were far more ac- curate than we could have gathered from surveying.” The work was also completed more than twice as fast. “We would typically have 21 survey crews working on this project, and it would usually take us more than two weeks to complete it. When we took it on with drones, it only took us nine days to collect this data, process it, and report results. This is the best way to survey stockpiles.” Calculating ROI for Drone Stockpile Surveys The strong return on investment the West Virginia team demonstrated early on really gave the program traction. WVDOT calculated it by comparing the cost of conventional surveying of stockpiles with surveys using drone technology. The conventional method took 42 surveyors 15 workdays, at a cost of about $378,000. With drones, the same workload took seven drone pilots only nine workdays, costing nearly $35,000. The department saved more than $343,000 in a single month. Expanding to Other Use Cases Considering aggregate is one of the biggest materials used in construc- tion projects, stockpile inspections are a logical first drone use case for many public agencies. In fact, about 50 percent of all aggregate is used for publicly funded construction projects. That includes highways, water and sewer systems, public buildings, airports, and other county and municipal public works projects. Today, WVDOT is considering expanding its drone programs to uses they think could provide more efficiencies and greater accuracy for the department: • Construction material cost estimates such as quantity takeoffs • Surveying and topographical maps as part of designing new road routes • Road safety assessments using point clouds • Drone-based LiDAR surveys to discover delamination of roadbeds unde- tectable to the naked eye From surveying aggregate stockpiles to inspecting bridges, drones are transforming what have often been expensive, accident-prone tasks for state transportation agencies. In spite of initial uncertainty, WVDOT’s experiment of using drones quickly expanded to a department-wide program, demonstrating benefits ranging from increased speed and ac- curacy to substantial cost savings early on. Drone advancements will continue to unlock new and more powerful use cases and following WVDOT’s steps of generating positive public perception and taking after other transportation agencies’ drone programs will help ensure your team is well positioned for growth and innovation in the future. SALLY HUYNH is the Senior Customer Marketing Manager at Skyward, a Verizon company. Sally is a professional marketing manager with a history of delivering successful programs that support company goals for customer acquisition, cross-selling, and retention. She also specializes in customer-focused marketing activities that build advocacy and loyalty while creating a world-class experience through the entire customer journey. When Sally is not being a fierce advocate for Skyward customers, she enjoys hikes with her best four- legged pal, Kona, and flies her Mavic to capture the beautiful Pacific Northwest.

dom of Information Act request from a property owner who asked for all of our drone footage. We had to give them all of the data, some 25,000 JPEG images.” Surveying Stockpiles with Increased Accuracy, Speed and Safety That was one of a few bumps in the road during the agency’s three- month trial stage. Surveying some of WVDOT’s 177 aggregate stock- piles was the department’s first use case. State highway departments store large piles of crushed rock, sand, salt, and gravel for road build- ing, maintenance, and winter traction. Constructing a two-lane asphalt highway requires nearly 25,000 tons of crushed stone per mile. West Virginia’s stockpiles include roughly a dozen classes of materials. These stockpiles must be physically surveyed annually to get an inven- tory. Until drones, such volumetric calculations have been completed in a few ways. One involves counting the number of trucks carrying bulk material, a method that one company found can cause inaccura- cies of as much as 20 percent. Alternatively, crews relied on surveyors to measure the piles, which required them to climb around hazardous stacks of shifting material. “It’s always been a project that none of our surveyors like to do, be- cause walking on gabion piles is a good way to get your ankle broke or break some piece of equipment. And then nobody believes the data because they’ve been counting trucks or tonnage,” explains Travis. The WVDOT survey team recognized potential for drones to speed up this process, reduce risk, and increase accuracy. Travis’ team made a small $25,000 investment in equipment and pi- lots. They set up a data model to verify the data they collected. Crews flew drones around stockpiles and quickly captured extensive imagery. These images were stitched together with software that builds 3D mod- els of the piles. These models can easily calculate the volume of stock- piles nestled against hillsides or inclining slopes, a task that’s difficult to do accurately using traditional methods. The team compared the data collected by drone to ground control points, and checked physical measurements in the model to confirm data accuracy. West Virginia Department of Transportation began using drones to survey 177 aggregate stockpiles, analyzing nearly a dozen classes of materials.



may 2021

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