A 19th Century Bridge Meets 21st Century Inspectors
Ottawa, IL – The sounds one hears any day around the Ottawa Lift Bridge in Illinois have not changed for more than a century. The Illinois River rushing underneath. The horns of passing barges. The rhythmic “clunk clunk” of freight trains slowly crossing the iron railroad bridge.
But recently that timeless medley was interrupted by a new sound: the methodical hum of unmanned aerial vehicles, flying in precise patterns around the classic structure. The 19th century railroad bridge was getting a 21st century inspection.
19Th Century meets 21st Century: Unmanned Experts’ Inspire UAV at the Ottawa Lift Bridge
In 1898, the Chicago, Burlington & Quincy Railroad, competing to establish a rail line from Chicago to the Mississippi River, built a flat railroad bridge across the Illinois River at Ottawa in northern Illinois. As barge traffic on the river got larger and taller, the center span of the bridge was refitted as a vertical “lift” section in 1932. The bridge has changed hands over the years, and stayed busy into the 21st century, but long haul rail traffic eventually migrated to newer, faster routes. Yet the bridge has remained economically relevant as part of a short line connection, and still serves to link commercial interests north and south of the Illinois River.
This May, the current owner of the structure decided to leverage state-of-the-art inspection techniques to gather the data needed to support extending the bridge’s service life. With its railroad infrastructure partner, it commissioned Unmanned Experts, Inc., to conduct an Unmanned Aerial Vehicle (UAV, or drone) inspection of the venerable railroad bridge.
Unmanned Experts’ team of Dave Prall, VP Special Projects and pilot-in-command, and JD Prall, project manager and visual observer, brought a fleet of UAVs for the inspection project, including an Aeryon SkyRanger, an AsTec Falcon 8, and a DJI Inspire. For two days they operated the drones from the shore and from a pontoon boat, flying programmed patterns to capture the ultra-high resolution images used to produce both 2D and 3D renderings of the bridge, from the sides, top, and bottom.
The team leveraged the complementary attributes of the aircraft. The Falcon 8, with a “look up” photo capability, was essential for inspecting the underside of the bridge. The SkyRanger allowed both precise close up shots and wide panorama shots in the same flights. And the Inspire provided an economical backup that could be quickly deployed for follow-up views.
“Flying a precise pattern around a bridge structure is deceptively challenging,” said Dave Prall. “Wind currents change constantly. The bridge’s metal structure can disrupt a drone’s compass, degrading directional orientation. And flying underneath a bridge blocks the GPS signals used for stability and positioning, forcing pilots to use a ‘manual’ drone flight mode.” The UMEX team is one of only a handful of groups in the industry with the experience, equipment and skills to safely and effectively conduct UAV-based inspections in such challenging situations.
While the flying requires intense concentration, Prall noted that the payoff is significant: each flight generates huge amounts of useful data. The bridge owners and their inspection partner are now using the inspection images to evaluate the integrity of trusses and joints and determine what, if any, maintenance or repairs are needed to extend the century-old bridge’s utility.
Panorama of the Ottawa Lift Bridge from the Versatile SkyRanger UAV
Some of the very same water that passes under the Ottawa Lift Bridge started its journey hours earlier flowing under two bridges to the northeast in the city of Blue Island, just south of Chicago. Those bridges, the Chatham Street Bridge and the Division Street Bridge, were closed years ago for safety reasons, leaving the center of the city divided by the Cal-Sag Channel canal.
Last year, Blue Island, working with civil engineering firm Lochner, began extensive upgrades of both bridges to return them to service, and in March they commissioned Unmanned Experts to conduct a cost-effective, efficient and safe evaluation of the structures with drone technology. Unmanned Experts pilots Dave Prall and Matt Wichern got the assignment, spending several days around and under both bridges with SkyRanger and Falcon 8 UAV aircraft.
Nearly $8 million has been invested in the renovation of the Division Street Bridge, which included replacement of structural steel, bridge pier renovation, and a fresh coat of “Blue Island blue” paint. The Blue Island community celebrated its reopening on August 4. The Chatham Street Bridge is in the final stages of being converted to a pedestrian-only bridge with the additions of sidewalks, landscaping, and an observation deck. Re-opening is scheduled for Fall 2016.
UAV View of the Division Street Bridge Under Renovation Prior to its August Reopening
Unmanned Experts’ Matt Wichern observed: “The exciting part of this project was knowing that our inspection results would accelerate the process of getting these bridges re-opened. Working from both ends of the bridges, we could see how the neighborhood, with both a school and a fire station next to the closed bridges, will appreciate having the bridges open again.”
About Unmanned Experts
Unmanned Experts Inc. (unmannedexperts.com) is a Colorado corporation providing world class Unmanned Aircraft Systems (UAS) managed services, consultancy, and training. Our team of professionals, with thousands of hours of both UAS and manned flight experience, helps clients across many industries evaluate and integrate UAS tools and processes to aid precision data collection, cost savings, and safety improvements. UMEX specializes in critical infrastructure inspections in the bridge, transportation, oil and gas, and power generation / distribution sectors; and is FAA-approved, through Section 333 exemptions, for commercial operations with more than 10 different aircraft types within a growing fleet. UMEX crews are OSHA-10 trained, NERC-screened and have peerless experience in the field. The company has undergone ISNetWorld Certification and is presently in the final stages of receiving the highest level of SGS Remotely Piloted Aircraft Systems (RPAS) Safety & Compliance Verification, the most comprehensive audit of safety systems and operational safety practices within the drone industry.
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