AEC Magazine |Published: 30 May 2017:
Built in 1949, the Pinto Creek Bridge is a historic crossing on Highway 60, an hour and a half east of Phoenix, Arizona at the foothills of the Tonto National Forest. Built as part of President Roosevelt’s public works initiative, the steel arch bridge sits atop a steep ravine offering scenic views of the surrounding countryside.
With over six decades of use, however, the bridge has started to show its age. Inspections and appraisals have returned poor ratings, and the bridge was considered “structurally deficient” in a 2014 review.
Though the bridge is still open and in use, its decay led to the decision to replace it. Because there are no easy detours on this roadway, the replacement bridge will be built just north of the current bridge, and then the old Pinto Creek bridge will be demolished.
The project is currently in its early stages: the Arizona Department of Transportation (DOT) has been conducting geotechnical surveys of the surrounding ravine, ensuring that the land is suitable for new infrastructure. Any new construction in this area must first go through an exhaustive survey process in order to ensure its sustainability and effect on the surrounding ravine within the Tonto Forest.
It’s vital that the bridge blends with its natural surroundings and has limited impact on existing plants and rock outcroppings. The ravine is approximately 80 metres deep, so traditional survey methods would require at least a day to complete the site from top to bottom. This includes using climbing equipment, abseiling down the ravine and walking the rocky terrain by foot, which comes with its own set of risks, hazards, and inefficiencies.
Surveying the Pinto Creek – a large, environmentally sensitive site with rough terrain – presented the perfect use case for drones, which are able to quickly capture aerial data and help land surveyors stay out of harm’s way. 3DR went to Pinto Creek and used Site Scan to capture the full context of the bridge and its underlying topology.
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Image Credit – Fair Use – Point cloud model of Pinto Creek Bridge, captured by drone: