How Combining UAVs with Cameras and Advanced Sensors Can Deliver Insights Needed to Reduce Costs, Speed Projects, Enhance Safety and Minimize Disruption
By Mike Stys
Anyone overseeing a construction, transportation, or utility project knows the pressure to come in on time and under budget. Given the number of factors that can impact a project from day to day, that’s easier said than done. However, having good data from site surveys at the start, and being able to continually assess conditions as a project progresses, can go a long way in minimizing the challenges that arise, costing the project valuable time and money.
The addition of unmanned aerial vehicles (UAV) – more commonly referred to as drones – combined with high-resolution cameras and advanced lidar sensors to the data collection toolbox makes it possible for engineering firms to gather more and better data, more frequently. In the process, these remote data collection platforms can help speed projects to completion and reduce overall costs, while improving safety by reducing the need for in-person site visits, and preventing disruptions to traffic and operations that are common with more traditional aerial or boots-on-the-ground surveys.
Drone Use Taking Off
The market for drones is exploding, with global shipments expected to reach 2.4 million in just the next three years according to Business Insider Intelligence. At same time, commercial drone applications, which generated about $18 billion last year, will grow to more than $42 billion, fueled by an increase in the energy, construction and engineering sectors, according to Drone Industry Insights.
Drone-based data collection is a game changer for these sectors. The adaptable-to-launch systems are able to get precise geospatial and site survey information to engineering design teams in a matter of hours and days, rather than the weeks or months it typically takes when using airplanes and helicopters, or sending surveyors into the field. And the advanced sensors and cameras carried by the drones can gather more detailed data than these traditional methods, too. This data is valuable not only in the design phase, but it can be leveraged later, if the project scope changes, inspectors have questions, or geospatial information is needed for other planning purposes or even emergency response.
While still in the early stages for civil and structural engineering use, drones cannot be used everywhere, given the current strict Federal Aviation Administration (FAA) line of site requirements. But they are ideal for a variety of specific tasks, including project development and management, construction surveys, safety inspections, volume measurements, and 3D modeling, as long as they are piloted by certified individuals with expertise in data collection and monitored by licensed survey professionals.
Getting First-hand Experience
For the past four years, my firm, NV5, has been deploying drones to tackle challenges that we were not able to solve with traditional aerial surveys. Because drones can fly lower, and slower, we are able to capture much higher resolution data, which helps inform our engineering team at every stage of their projects.
We rely on a combination of cameras and lidar sensors mounted on UAVs for site surveys and inspections. As a result, we can collect high-resolution imagery to form a 3D model that can be used to measure true distances, both horizontally and vertically. This information is valuable because it aids in our site surveys and pre-construction planning and pricing, such as making volume calculations for moving dirt and determining the best routes for roads, transmission lines or pipelines. We also use the images to document the construction process to mitigate liability and provide insights to executives at headquarters without requiring them to visit the job site.
Lidar – or high-density light detection and ranging technology – uses laser light to map physical environments, penetrating vegetation and other minor obstructions. We use state-of-the art sensors, which enable us to generate accurate horizontal position and vertical elevation data. From that, a point cloud, comprised of millions of elevation data points, is used to map terrain and help engineers visualize both natural and manmade objects in and around our project sites.
Drone + Advanced Data Collection Tools Deliver on Operational Improvements
Since we started using drones for data collection, we’ve seen a number of improvements, including:
- Speed, comprehensiveness and efficiency of data collection – The comprehensive and thorough data collection inherent with combined photographic and lidar surveys have eliminated the need to remobilize personnel for follow-up site visits. This will save a minimum of $2,500 per each site revisit day. We typically see time savings of up to 40 percent for mapping quality data collection vs. traditional or conventional methods. More importantly, the quality, precision and high level of detail is unmatched with any other method or tool.
- Better risk management – Remotely capturing survey grade data in busy roadways or other inherently dangerous geographies immediately improves surveyor and public safety. For example, when doing surveys, firms often have to shut down roads or put in place traffic control measures, which often come as a surprise to drivers. Using drones, instead of boots on the ground, surveyors do not need to venture into highly traveled or risky geographic areas and eliminate driver or pedestrian obstacles.
Using UAVs for low altitude, very high resolution ortho-mosaic photography, combined with high precision lidar, also helps reduce risk by producing survey grade measurable aerial photos and point cloud data. This high quality data helps designers more accurately interpret features on the ground, both horizontally and vertically, and avoid major design errors. A hillside with heavy vegetation is shown in the pictures below. A detailed topographic image of existing surface conditions is needed to properly plan earth movement, which is one of the highest costs in most construction projects, thus the highest risk. These images show the amount of detail that is captured with the photography and lidar that penetrates vegetation and provides a very accurate model of existing conditions for base engineering efforts.
- Reduction of injuries – Because the existing condition data is collected remotely and quickly with a UAV, it can be assumed that injuries to field surveyors will significantly reduce. While there are no specific quantifiable numbers supporting this, we can apply some basic risk reduction principles to prove this. In short, fewer people in dangerous areas or unstable ground will certainly reduce injuries.
- Minimized community impact – This goes hand-in-hand with both previous benefits. Using drones to remotely capture data eliminates our need to change traffic patterns to accommodate surveys, which minimizes bottlenecks and frustrations for commuters. And the increased efficiency enables us to complete our projects faster and minimize the disruptions construction projects may have to surrounding areas.
Building Strong Best Practices
If you are interested in adding drones and advanced sensors to your data collection toolbox for gathering survey-grade data, there are some important best practices to consider in your implementation:
- Establish safety protocols – Safety must be priority #1. All equipment should be inspected thoroughly before and after every flight. Additionally, those individuals involved in the UAV-based data collection should be properly trained and FAA certified, follow all FAA flight safety and company-specific rules, and have a detailed knowledge of the area being surveyed to minimize risks. One thing that you may need to also be aware of is the distraction even drones can cause. Many companies use light-colored drones, instead of black ones, so they blend into the sky and are less noticeable to passersby.
- Planning, and more planning – Before doing remote data collection, meet with design engineers to coordinate on the survey plan. Be sure to ask hard questions about factors within the project that could possibly change over time. With an understanding of these variables, the survey can ensure that the correct data is collected to address changes in project scope or questions that may arise about feasibility.
- Implement survey control – Drone-based data collection for engineering is not for the hobbyist drone pilot. The process is much more complex than simply putting a drone in the sky and taking pictures. Licensed surveyors must work hand-in-hand with certified UAV pilots trained in data collection to ensure accuracy.
- Review data before leaving the job site – There are a lot of moving parts involved in UAV-based data collection. You need to make sure the hardware works properly and that GPS is locked to provide accurate results. It’s vital that while still in the field, you double check the data collected. If you wait to review the data back at the office, you may have to retrace your steps and resurvey the site, adding cost and time to the project.
- Consider other applications of sensors and drones to support operations – High-def cameras and lidar sensors are not the only types of devices that can be attached to drones. Consider how you may be able to leverage other sensors for hyperspectral or multispectral imaging to more specifically identify vegetation species or explore surface contamination, or thermal imaging to explore conditions of rooftops to proactively address areas where leaks may occur. Furthermore, these thermal images of the building exteriors can highlight energy loss, and can contribute to a comprehensive energy efficiency plan.
Civil and structural engineers are just in the early stages of discovering the many ways drones benefit their operations. While some hurdles still exist – particularly concerning FAA line of site restrictions and security concerns with UAVs from foreign manufacturers – these should not stop the engineering community from exploring new applications for UAV-based data collection. With strong practices in place; collaboration between design engineers, surveyors and drone pilots skilled in data collection; and an eye toward trying new approaches, the sky’s the limit.
NV5 is a provider of professional and technical engineering and consulting solutions firm serving public and private sector clients in the infrastructure, energy, construction, real estate, and environmental markets through more than 100 locations worldwide. NV5 primarily focuses on five business verticals: construction quality assurance, infrastructure engineering and support services, energy, program management, environmental services, and technology solutions, including geospatial services through its subsidiary Quantum Spatial, Inc., the largest full-service geospatial solutions provider in North America.
Mike Stys, Vice President at NV5, has 20 years of experience managing infrastructure engineering design and survey projects, utilizing his technical expertise and results-oriented technology solutions that increase accuracy, minimize costs, and help to deliver projects on schedule.