Finding Success with Combined Technologies
Proven successes and conveniences are never more prominent than within the LiDAR side of land surveying. Having a variety of survey-grade tools is just part of data acquisition. Understanding the best way to use them and which tool to use while maintaining a common workflow can be just as important in achieving successful projects. Civil engineers require unique solutions for a multitude of design applications. Design is dependent on the amount and quality of site data, which is a direct result of the tools used. TREKK's use of combined technologies aides in design that is safer and more efficient.
“No two civil engineering projects are alike, but they have similarities that complement each other,” said TREKK Associate Partner and Transportation Lead, Tawn Nugent. “Our many LiDAR tools aid with that line of constraint when using only one tool may limit the data collected from the field.”
TREKK’s toolbox includes:
Terrestrial mobile LiDAR traveling on the roadway at posted highway speed collects up to a million points per second. TREKK uses this technology to acquire data along entire roadway corridors and side streets. Driving each lane on the roadway allows 100 percent coverage of the pavement surface to an accuracy of plus or minus 0.05 feet. Terrestrial mobile LiDAR also covers much of the right-of-way outside of the pavement surface. TREKK’s mobile LiDAR system can be transformed into three different configurations—a backpack, vehicle-based or Unmanned Aerial Vehicle (UAV) helicopter system—to meet the needs for a range of applications and environments.
UAV LiDAR gathers a wider swath of data in less time. It can generate 100,000 points per second with up to five returns per laser pulse, allowing greater penetration through vegetation. UAV LiDAR is used to supplement terrestrial mobile LiDAR and UAV photogrammetry. Because of its high nadir vantage point, TREKK uses UAV LiDAR data to fill in occluded areas of roadway slopes like ditches and vegetation. The systems navigation can achieve final position accuracies of plus or minus 0.15 feet.
UAV photogrammetry maps open area corridors, providing high definition digital orthographic photos and colorized 3D points at 0.5-inch intervals. We acquire UAV photogrammetry to create a rich, colorized 3D point clouds, which can achieve final position accuracies of <0.05 feet.
TREKK’s experience combining many tools and platforms to collect rich point cloud data has been powerful on many projects. When TREKK was faced with a midsummer, leaf-on situation last year for a railroad project, the combination of mobile LiDAR mounted on a hi-rail and UAV LiDAR application provided the solution. This spring, TREKK used the combination of survey tools and the varying aspects of terrestrial mobile LiDAR, UAV LiDAR and UAV photogrammetry to establish the base mapping for a more than $100 million transportation project in southeastern Nebraska. Within two days, we acquired 8.33 miles of two-lane highway, 2.71 miles of cross streets and 700 acres of farmland areas outside the current right-of-way. On both projects, data was merged from combined LiDAR tools to fill in occlusions not otherwise obtained using only one collection tool. In both cases, the resulting LiDAR data set was used to extract a 3D CAD model for engineering design.
TREKK projects often involve underground storm and wastewater identification when designing for transportation. The confined space LiDAR tool and TREKK360 cameras provide a geo-referenced location both below and above ground. We used the combined tools of underground storm sewer LiDAR and above ground mobile LiDAR to create a complete digital topographic survey for the Kansas City Streetcar through some of the most complex utility corridors found in Kansas City.
TREKK recently leveraged the power of its static and mobile LiDAR tools to survey a wastewater treatment plant. Traditionally, the process of documenting a plant environment included labor-intensive hand measurements of piping and tanks. This LiDAR combination provided a safe, comprehensive and cost-effective way to create necessary 3D models for the design process.
“It’s not redundant data, and it’s not overkill or over collecting,” said TREKK’s LiDAR/Survey Manager Michael Frecks. “Each tool has unique aspects that provide for a complete and accurate survey and that provide unique advantages during data extraction and QA/QC cross checks built into the final deliverable.”