Sunday, July 02, 2017

Multnomah Creek Bridge

Next up, here are a few photos of the historic 1914 highway bridge at Multnomah Falls. (Did I mention there's an ongoing Columbia Gorge bridge project? Because there is.) The comprehensive Historic Highway Bridges of Oregon (1989) describes the bridge thusly (via

The Multnomah Creek Bridge, near the 620-foot drop of Multnomah Falls, is a noteworthy short-span arch and is a significant component of the old Columbia River Highway. This reinforced concrete deck arch is 67 feet in length .The barrel arch has solid spandrel walls and is 40 feet in length. The bridge was designed by K.P. Billner under the supervision of C.H. Purcell, State Bridge Engineer, and S.C. Lancaster, Assistant State Highway Engineer. It was constructed [in 1914] by the Pacific Bridge Company of Portland.
Smith, Dwight A., James B. Norman, and Pieter T. Dykman. Historic Highway Bridges of Oregon. Portland, Or: Oregon Historical Society Press, 1989, page 143.

It's not the biggest or most innovative of the old highway's bridges; a 1915 Engineering and Contracting article by Billner describes various bridges along the highway and the engineering challenges they addressed, and the Multnomah Creek bridge only merited a brief mention: "Figure 7 shows two bridges of the arch type at Multnomah Falls. This view also shows the falls, which is one of the scenic attractions along the highway.". The other of the two arch bridges is the famous Benson Bridge between the upper and lower falls, so I gather the key design feature here is that the two bridges were meant to form a harmonious pair. Most of Billner's article is devoted to his bridge at Latourell Creek, and my post about that bridge has a bit more background on Billner (who still doesn't have his own Wikipedia bio, somehow).

Elsewhere around the interwebs, the bridge also has the usual Structurae and Bridgehunter pages, and the Library of Congress has a couple of vintage photos of it. And of course there are lots of other photos of it around the interwebs. The waterfall is obviously the main event here, but seeing as it gets multiple millions of visitors per year, a few of them are bound to take an interest in the old arched bridge they pass on their way to the gift shop. The bridge also gets a mention in a recent ODOT presentation about mathematical buckling analysis of arch bridges. It has a section on "Common Arch Bridge Types", and cites a few Oregon bridges for each type, since ODOT has lots of arch bridges and I gather they're rather proud of them. I dunno, I think stuff like this is interesting even if I don't completely understand it.

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