The bridges spanning the Willamette River in Portland, connecting the main downtown core to the east side of town, serve as more than just a few pretty features and a practical way to cross the navigable channel in “Bridgetown,” they also provide plenty of national engineering history.
With 11 bridges connecting Portland’s two distinct sides, transportation officials from the state and Multnomah County nominated the Broadway, Morrison, Burnside and Hawthorne bridges—each with a distinct historical and engineering significance—for listing on the National Register of Historic Places.
Using information presented to the State Historic Preservation Office of Oregon, we get a clear view of why each of these four bridges contain significance worth celebrating:
The oldest bridge in the bunch opened to traffic on Dec. 19, 1910. A steel through truss designed by Waddell & Harrington of Kansas City, Mo., serves as the oldest operating lift span in the country. It is also the most powerful lift span in the U.S.
The 1,383-foot-long bridge uses a system of counterweights and cables for the roughly 200 openings per month. The system is mostly original, but the electrical power and control systems were installed in 1975 and upgraded in 1999. Hawthorne’s counterweights each weigh 450 tons and are supported by the bridge’s two towers, which rise 165 feet above the bridge deck. The Hawthorne Bridge’s main span can rise 110 feet to allow vessels to pass underneath.
Opening just three years (1913) after the Hawthorne Bridge, the Broadway Bridge features six steel through trusses, with the center span a 278-foot-long double-leaf Rall bascule. Designed by Ralph Modjeski of Chicago with the operable Rall span (created by, you guessed it, Theodore Rall) designed under patent by the Strobel Steel Construction Company of Chicago, the bridge boasts the heaviest Rall-bascule in the U.S. and is the seventh-longest bascule bridge in the world.
But all this history can frustrate drivers. The average opening times for the Morrison, Burnside and Hawthorne bridges is five to eight minutes, while it can take longer than 20 minutes at Broadway. The complicated double-leaf bascule has counterweights located above the bridge’s deck, not concealed below, and each leaf and its counterweight roll back and forth on giant bull wheels to allow maximum river clearance. It opens about 20 times each month.
The first bascule bridge to rely on a concrete deck (and at 5,000 tons, it has some heft to it) for its movable span, the Burnside is one of the heaviest bascule bridges in the U.S. A steel deck truss with a central, double-leaf Strauss bascule, the bridge measure 788 feet long and was designed by Hendrick and Robert K. Kremers of Portland. It opened in 1926.
The only Willamette River bridge designed with the assistance of an architect, the Italian Renaissance towers give Broadway a bit of an ornate touch. A mix of steel and concrete construction provides a bit of diversity in the makeup of the bridge, which has gone largely untouched since opening.
While opening much later than the other three bridges (May 1958, to be precise), the Morrison Bridge offers a steel deck truss span rising from concrete piers with a two-leaf Chicago-type central bascule span. Two previous bridges in the same location, in 1887 and 1905, precede the current version.
The Morrison Bridge main river structure consists of two nearly 238-foot steel deck truss side spans and a nearly 285-foot double-leaf Chicago type bascule draw span, for a total bridge length of 760 feet. It requires 30 openings per month. Sverdrup/Parcel of St Louis and Moffatt, Nichol and Taylor of Portland designed the bridge.
If the process proves successful to get the original four bridges onto the national register, don’t be surprised to find other Willamette River bridges up for the nomination soon.
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