2019 CSCE Annual Conference - Laval (Greater Montreal) Conference
Mr. Michael Paulsen, Associated Engineering
Routine visual bridge inspections are an integral aspect of maintaining a road network in a safe and serviceable condition. In Alberta for bridges with challenging access, up close visual inspections will often use snooper trucks to gain access to hard to inspect places, such as deck undersides and bearings. At times, due to factors such as a bridge’s configuration and traffic usage, carrying out an inspection can be time-consuming, expensive and hazardous.
In 2018 the City of Medicine Hat required up close visual inspections on two of their major bridges, including the Finlay Bridge (a 5-span through-truss) and Maple Avenue Bridge (a 7-span prestressed girder bridge) both spanning the South Saskatchewan River. The Finlay Bridge presented major challenges to completing the underdeck inspection by snooper truck including conflicts with the truss diagonals and a load restriction that would require full closure of the bridge. Various options were reviewed including rope access, however the decision was made to supplement the visual inspection by use of Unmanned Aerial Vehicles (UAVs).
There is significant experience in UAVs in industry for overall site photos and exploring certain defects. However, completing up close visual inspection of a bridge by use of a UAV presented unique challenges that needed to be addressed. In Alberta, UAVs have not previously been used to supplement detailed visual inspections, and there is minimal literature discussing the use of UAVs in this method across the country. As such, the methodology to complete the inspections was developed unique to these bridges.
This paper presents the case-studies of the Finlay Bridge and Maple Avenue Bridge inspections. It covers the inspection methodology and the logistic challenges faced in completing the unique bridge inspection method. Items such as predetermined flight paths and identification of critical elements in advance of the inspection were key to success. The technology used is discussed and outcomes, benefits, and next steps are discussed.