How Drones are Speeding Up Construction
Drones, or unmanned aerial vehicles (UAVs), are being used in many industries, e.g. agriculture, construction, mining, oil & gas, mapping, and surveying. In construction, drones have proven to be quite disruptive, offering huge productivity increases.
Gartner’s famous Hype Cycle for Emerging Technologies, 2016, positioned drones as just entering the Peak of Inflated Expectations. Gartner claims that, “Smart machine technologies will be the most disruptive class of technologies over the next 10 years due to radical computational power, near-endless amounts of data, and unprecedented advances in deep neural networks.”
Commercial UAVs are one of the smart machine technologies in question, together with smart robots, autonomous vehicles, cognitive expert advisors, and others.
Surveying in the 1980s
I was involved in a holiday resort construction project in the late 1980s. Back then, state-of-the-art land surveyors used equipment and software that created a 3D surface model of the site. But first they had to walk over the site and manually mark every point that they wished to measure. They had a recorder that collected the data taken at the measured points. Back at the office, they imported the data into a CAD system and created a 3D mesh that we architects could use in the design work.
The resulting mesh was unfortunately quite crude. We had to return to the site to make additional measurements by hand. Pioneers don’t always get it right the first time.
From manual theodolites to 3D scanning and sensors
I’m not an expert in surveying, but I’ve noticed that often, field work today still looks quite similar. The theodolites and prisms must be placed accurately on the site and the points must be measured one by one.
3D laser scanners (LiDARs) will eventually replace the old technologies, both on the ground and in the air. They are based on a rotating laser transmitter/receiver that automatically scans the site around them. The scanning system creates a “point cloud” of the data, a 3D model consisting of hundreds of thousands of accurate points. Or, instead of using a laser, a high-resolution camera is a viable option if the environment is not occluded by objects, e.g. trees.
Drone cameras can see more than just the visible surfaces. Thermal and multispectral cameras open whole new views on the environment. Furthermore, drones can be equipped with sensors for light intensity, pressure, gas vapor, radiation, sound, etc. With good equipment and sufficient computational power, models from drone data are accurate to the centimeter-level.
Here are three examples of how drones speed up processes at three levels: areal, site, and detail.
Super-fast surveying of large areas
The killer feature of drones is their speed. According to Identified Technologies, the lead time of a traditional aerial survey of a 100-acre area (400,000 sqm) by helicopter is about 12 weeks. The total time includes a four-week booking lead time, data gathering, and data processing. For a manned survey team, the lead time for the same task is about seven weeks, of which data gathering takes four weeks. A subscription drone service gathers the data in nine minutes and provides the whole service in six hours!
Real-time information from the construction site
UAVs help project managers track the day-to-day progress of even large construction sites. A well-known example from 2016 is the Sacramento Kings’ Golden 1 Center arena construction site. A team from the University of Illinois, funded by a grant of nearly $1 million, developed predictive visual data analytics tools to automate and streamline the practices for monitoring construction progress. The innovation won the Turner Innovation Award.
3D Robotics has commercialized worksite tracking with drones. Its Site Scan™ construction drone platform allows contractors to overlay imagery collected from the drone with the original design. Their service is directly integrated with Autodesk’s design software.
Inspection of inaccessible areas is another perfect application for drones. Recently, a team at the Minnesota Department of Transportation explored how drones can be used to reduce costs and minimize risk for employees. The study revealed that drones have many benefits over traditional methods: improved worker safety, no need to stop the traffic, and overall lower costs. Drones can provide both infrared and 3D modeling detail of bridges, identify concrete delamination, gather topographic mapping detail, and efficiently map riverbank conditions.
The reduced cost of inspection is significant. To inspect the second-largest bridge in Minnesota would cost at least $59,000 and take eight days, the study says. In contrast, the cost of a UAV contract would be around $20,000, with five onsite days – a potential cost saving of 66%.
Own fleet or service?
Drones are high-tech equipment, but the prices of professional drones have come down considerably over the last few years. Professional-grade drones with high-definition cameras can cost less than $10,000, but price tags of $50,000 or more are possible for high-end solutions. In addition, you need software, and professionals to operate the drones.
Many companies consider operating their own drone fleet. If they calculate the total lifetime cost of ownership, alternatives such as leasing and using drone service providers may make better financial sense.
Automation will make drones easier to deploy. There will be uses where human intervention will not be needed, except for using the collected data intelligently.