Monday, March 31, 2014

Shepperds Dell Bridge

As you may have noticed by now, I've been making another pass through my old Columbia Gorge photos and digging out pictures of historic bridges along the old Columbia River Highway. This combines two of this humble blog's longtime OCD-ish preoccupations: The Gorge, and bridges, and the more I think about it the more I'm surprised I hadn't gotten around to this until now. For the benefit of anyone from out of town who's reading this, the Columbia Gorge is where the Columbia River cuts through the Cascade Mountains, forming a wide steep-sided canyon, with a large number of waterfalls where side streams drop into it. It's the only way through the Cascades that doesn't involve a high mountain pass, so it's been a main transportation route as far back as archeological records go in this part of the world, perhaps back to pre-Clovis times. Today, Interstate 84 runs along the Oregon side of the river, and Washington's SR 14 runs along the river's north bank, with busy rail lines parallel to each of these roads. A century ago, the original Columbia River Highway wound its way through the Gorge from Portland out to The Dalles. It was a showpiece of early 20th century civil engineering, as well as one of the region's first paved roads.

The old highway had to cross quite a few streams on its way east, and the state invested more than was strictly necessary in creating attractive bridges to fit their surroundings. The segment east of Hood River, which was built in the early 1920s, features a few bridges credited to Conde McCullough, the famous bridge engineer, and the guy whose designs show up in coffee table books a lot. The earlier western segment of the highway features bridges designed and built by some far more obscure names: Lewis W. Metzger (who designed the bridge at Eagle Creek, among other things), Charles H. Purcell (who created the state's bridge division, and who later was chief engineer constructing San Francisco's Bay Bridge), and Karl P. Billner, who designed many of the Gorge's more famous bridges, like the Benson Footbridge at Multnomah Falls; the Latourell and Bridal Veil Creek bridges; and the subject of today's post, the Shepperds Dell Bridge, which crosses Youngs Creek in Shepperds Dell State Park.

Like many bridges on both sides of the Gorge, the one here is a concrete deck arch bridge. That seems to have been the vogue at the time, and multiple designers went with it independently. So while the Shepperds Dell Bridge is a reasonably common design, it was a cutting edge one at the time, and it's a great example of the style. The setting doesn't hurt either, it must be said. As with a number of other bridges along the old highway, it was surveyed in 1990 for the National Park Service's Historical American Engineering Record. The resulting description goes into a great deal of detail about how the falsework was done, the exact dimensions of joists, later repairs to bridge railing spindles, that sort of thing. It's all there, if you're so inclined. Which is to say that someone who was truly obsessive about the subject could only use this humble blog as a mere starting point. It's almost as if I'm reasonably normal and well-adjusted, relative to this other hypothetical person.

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