Nothing helps a bridge, especially a High Bridge, like a picturesque setting. The 1926 Crooked River High Bridge, over the Crooked River gorge in Oregon, has about as dramatic a backdrop as you can get. It’s not exactly the untamed wilderness – this is a major road between Bend and Portland – but it’s relatively unpopulated nearby, and on a tourist route to several national parks. When a larger bridge was built in 2000 to carry the increasing traffic, the old bridge as kept as a pedestrian path.
A steel deck arch is a logical bridge form in a deep gorge, where the height of the bridge does not create any problems In this case, the bridge is roughly 300 feet above the river and the arch span is 330 feet. The bridge was constructed at an interesting moment in the apparently never-ending argument between advocates of steel and those of concrete. The bridge is made of built-up, riveted steel box members (solid for the arches, latticed for the other members), which is part of a tradition that was then going on fifty years old. The engineer, Conde McCullough, was one of the few who seemed comfortable switching back and forth between materials, and designed large bridges in steel, in reinforced concrete, and using both materials. At Crooked River, he designed a concrete handrail and side spans to go with the steel arch:
For me, the striking detail of this bridge is not its height or the incongruous appearance of a concrete handrail on a steel arch, but McCullough’s absolute faith in the gorge’s bedrock. Here’s a view looking east:
Sure, there’s some kind of bearing assembly there and probably even some concrete below the steel bearing, but this is as close as I’ve seen to a steel arch simply hitting rock the way some masonry arches do. A high bridge can have river piers, although the short main span here makes them unnecessary, but there’s an iconic quality to a high bridge that spans between the walls of a steep valley, and this design makes the most of it.