Tackling a Natural Disaster: UAS and GIS Technology Delivers Data Three Times Faster
Send in the Drones: Using UAS and GIS Technology to Map Flooded Roads and Bridges in Midland County
2017 was a year of natural disasters. While floods in Houston and wildfires in California grabbed national headlines, the Midwest wasn’t spared weather wrath.
In late June, five to seven inches of rain within a 12-hour period pummeled parts of mid-Michigan. Overnight, the Tittabawassee River topped 32 feet – the second highest level in recorded history – and caused significant damage in Isabella, Midland, and Bay Counties.
Midland County Hit Hard
The historic rainfall and flooding caused almost $7 million in damage to the roads and bridges of Midland County.
Within days of the storm, Michigan’s Lieutenant Governor declared a state of disaster. More than 2000 homes were damaged. From sinkholes to missing sections of roadway, the rain and high water affected 105 roads and caused culvert and bridge damage in multiple locations – limiting access to sections of the county.Nearly two dozen roads closed temporarily, including major thoroughfares such as the east and westbound sections of US-10
With major roadways closed, travel time significantly increased, and residents had to find alternative routes to services. County officials were concerned about the region’s elderly population and wanted to start infrastructure repairs quickly so that emergency vehicles could get where most needed.
Midland County Road Commission called on OHM Advisors to survey flood damage in the worst areas to understand the extent of the impact and to begin repairs. OHM Advisors was tasked with surveying nine sites, roads and bridges in areas that weren’t easily accessible by vehicle or on foot.
Send in the Drones
The survey team’s job was to get data to the people responsible for infrastructure solutions as quickly as possible to minimize the impact on the residents of Midland County. To expedite the damage assessment and still work safely within unstable areas, OHM Advisors used an innovative tool set: unmanned aircraft system technology (UAS) and advanced GIS software to document the storm’s impact on roads and bridges.
UAS technology, commonly known as drone technology, is growing in popularity and is already being used in a wide array of business applications. In Puerto Rico, Duke Energy is using commercial drones to find and repair the downed power lines caused by Hurricane Maria. Farmers are using drones to assess soil conditions and make better decisions about crops. And in 2017, ecommerce behemoth Amazon tested drone package delivery in Palm Springs, California. Goldman Sachs estimates that the commercial and civil drone industry will grow to $13 billion by 2020.
To begin to assess the conditions, two of our FAA-certified surveyors – a pilot and a visual observer – used the drone, DJI’s Phantom 4 Pro Quadcopter (P4P) to collect aerial photographs. We created an overall map of the area using GIS applications to document the County’s damaged infrastructure.
With ESRI’s Drone2Map (v1.2) software, the survey team established survey control points, (also known as Ground Control Points or GCPs), for accurate X, Y and Z values for the topographic mapping. The GPCs served as aerial targets for positioning and produced more accurate horizontal and vertical data than using UAS technology alone.
Armed with the Ground Control Points, the survey team delivered orthomosaic imagery and topographic mapping to design engineers at OHM Advisors. (Orthomosaic or ortho photos are images that have been orthorectified. That is, they’ve been geometrically corrected so that the scale is uniform. An orthomosaic image can be used to measure true distances, having been adjusted for things like lens distortion and camera tilt.)
OHM Advisors’ GIS team created detailed maps of the terrain and conditions in ArcGIS Pro (v2.0.1). In addition, the team captured birds-eye footage of eroded bridges, jammed culverts, and destroyed roadways with video.
UAS Technology Advantages
Using UAS or drone technology has three major advantages over traditional surveying methods:
Safety – UAS technology provides a safer means to inspect dangerous areas like under bridges, the edges of crumbling roadways, or near high waters with floating debris. This is because operators can stand at a distance from unsafe areas to collect imagery instead of taking their equipment into a constricted space with water, open manholes, and uprooted trees.
Speed – With traditional methods, surveying nine sites would typically take nine days or one day per site. After the initial data collection in the field, there’s typically another week required to process that data in the office. From start to finish, this project took just five working days – three times faster than typical surveying. The rapid turnaround put critical information in front of the engineering design team right away, which allowed them to prioritize and address infrastructure repairs more quickly.
Quality – The ability to fly lower than manned aircraft often results in higher quality data. Additionally, because UAS mapping captures more data than traditional surveying (millions of points versus a few hundred of points for these projects), surface models are more detailed. With UAS, operators can capture elevations not possible with traditional survey, as well as quickly and accurately calculate items such as the amount of earth to be replaced in eroded areas.
GIS for More Detailed Conditional Assessment
OHM Advisors’ GIS professionals used ArcGIS Pro (v2.0.1) software to import the captured survey data and produce large-scale detailed maps for conditional assessment. This overall map assisted the ground team in determining the best access to these sites, as many of the routes were impassable.
Because ArcGIS Pro (v2.0.1) exports directly into many different software suites, it was easy to share terrain maps with the Midland County Road Commission. Rather than having to deal with new software or additional procedures, traditional CAD technicians can view information in the same format as any other survey data.
The ArcGIS Pro maps showed potential scour locations along the streams in real-time and allowed the team to acquire additional data without revisiting the site – as is often necessary with traditional means. Having this level of detail at their fingertips helped the design engineers and Road Commission make informed decisions about restoration more quickly.
“I’m extremely pleased with how quickly they were able to get information to the design team for solutions. With so many other things to worry about, this was of incredible value.” – Terry Palmer, Managing Director of the Midland County Road CommissionHaving this level of detail at their fingertips helped the design engineers and Road Commission make informed decisions about restoration more quickly.
When Every Day Counts
Flooding is the most common and costly natural disaster in the country. In 2016 alone, the U.S. endured five flood-related disasters that each caused more than $1 billion in damages.
Communities and consulting firms need to react quickly to minimize damage to the economy, the environment, and people. Using relatively inexpensive UAS technology and GIS software is a better way to gather storm damage information.
From a broader perspective, increasingly popular tools like UAS technology and GIS software are helping to create ‘smarter’ communities. Infrastructure planning, inspection and documentation have traditionally been managed via earthbound, costly and labor-intensive methods.
Now drones and data-crunching software are a driving force that is advancing the building, operation and maintenance of our infrastructure.