In 1932, Clark and Cowlitz counties erect Yale Bridge (aka Lewis River Bridge) to span Lewis River on State Route 503 not far from the town of Yale. The Lewis River is the boundary between Cowlitz and Clark counties. The Yale Bridge is the only short-span steel suspension bridge in the state of Washington.
Yale Bridge replaced a steel truss bridge that was demolished with the creation of Ariel Dam. The backwater of the dam created a depth of 90 feet at the site of the bridge, and made necessary a new, higher bridge. The concrete piers of the previous bridge were used for the new bridge.
An Ingenious Design
The Yale Bridge was designed by Washington state Highway Department engineer Harold H. Gilbert and built by the Gilpin Construction Company of Portland. It successfully employs an unusual design the purpose of which was to build an economical short-span bridge across very deep water.
The cables of most suspension bridges are threaded through a "saddle" at the top of the towers. Yale Bridge towers have no saddle. Instead the three-inch, galvanized steel cables are strung in separate sections, each one linked to the top of the tower by steel castings and pins and linkages. This eliminates the wear of cables because "under load" (when a vehicle is crossing the bridge) the cables are not sliding back and forth in the saddle as in a typical suspension bridge. This enabled the use of smaller, less expensive cables. The cables are strung from two towers.
Cables Carry Less Bridge
Also, timber trestles support the approach spans, not cables as in most suspension bridges. The unloaded "backstays" (cables) are anchored into the river canyon's rock banks with reinforced concrete anchors.
In summary, there are two approach spans resting on timber trestles, a 300-foot steel suspension span suspended from two towers (88 feet 9 inches high), with backstays anchored to the ground and carrying no load. The roadway is 17 feet wide and is suspended 50 feet above water level. It is a timber deck with an asphaltic concrete overlay.
The bridge was transferred to the Washington Department of Highways in the late 1930s. It was rebuilt in 1957 and 1958. Since 1977, the Washington State Department of Transportation has owned it.
Clark and Cowlitz counties erect Yale Bridge across Lewis River in 1932.
- By Priscilla Long
- Posted 3/14/2003
- HistoryLink.org Essay 5417
Sources:
Paul Dorpat and Genevieve McCoy, Building Washington (Seattle: Tartu Publishers, 1998), 128; "Yale Bridge," Environmental Affairs, Washington Department of Transportation Website (http://www.wsdot.wa.gov/environment); Robert W. Hadlow, "Yale Bridge (Lewis River Bridge)," (Historic American Engineering Record HAER WA-87), Library of Congress American Memory Website accessed March 14, 2003 (http://memory.loc.gov).
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