The Puget Sound Bridge and Dredging Company of Seattle built the bridge and the Washington Department of Highways (now Washington State Department of Transportation) purchased it in 1935. In 1949 the Department of Highways built a swing bridge just to the south at Huron Street. Today (2005) the Wishkah River Bridge carries the westbound traffic of U.S. Route 12 across the river while the Huron Street Bridge carries the eastbound traffic.
How It Works
The typical bascule bridge works like a seesaw with a moveable leaf and a counterweight attached to its "heel," a pivot much like the pivot at the center of a seesaw. When the bridge opens, the counterweight dips into a counterweight pit. This seesaw-like arrangement enables a bridge to open and close with a minimum of power provided by a motor.
The Wishkah River Bridge is a Strauss "heel-trunnion" bascule bridge and this differs in that the moveable leaf and counterweight each rotate around separate heels (called "trunnions"). Thus the counterweight rises and falls in a tower and doesn't require a counterweight pit. The energy is transferred from the leaf to the counterweight through a system of gears arranged in a parallelogram. The dead load of the bridge (the weight of the bridge itself) can thus be divided between two different piers, which allows the piers to be less substantial and more economical.
The leaf (or lift span) is a "through" truss, that is, elements of the truss are braced both above and below traffic. The Warren truss, composed of riveted steel pieces, supports a 27-foot-wide road deck and five-foot sidewalks on either side.
The original deck was made of planks and timbers. In 1946 wood decking was replaced with a steel grid. A new control tower was built in 1950. The 351-ton bridge is painted every 10 years. It now opens rarely, since river traffic is now sparse.
Joseph Strauss
Joseph Strauss, founder in 1902 of the Chicago-based Strauss Engineering Company, was one of the most prolific engineers and inventors of the early twentieth century. He introduced concrete arched bridges to the United States. He specialized in moveable and long-span bridges, and eventually renamed his firm the Strauss Bascule Bridge Company.
Strauss was born in Cincinnati to an artistic family, and grew up to be a short (five-foot, three-inch) man who aspired to be a poet. Along with his activities as a bridge engineer and inventor, he wrote poetry for his entire life.
Strauss invented several types of bascule bridges that were in limited use for very short spans due to the heavy weight of the cast-iron counterweight. He also invented the bulkier but lighter concrete counterweight, as well as the "heel-trunnion" type described above.
By 1927 he had designed 267 bascule bridges around the world, many of which established records for span bridges. He also designed fixed-span bridges including, in Washington state, the Columbia River Bridge at Longview, which was the longest cantilever bridge in the world at that time.
Strauss was construction engineer for the George Washington Memorial Bridge in New York City, at the time the second largest span in the world, and he was chief engineer for the Golden Gate Bridge in San Francisco, a suspension bridge. Strauss invented various other things as well, including a safety net that saved the lives of 21 workers during construction of the Golden Gate Bridge. Altogether he and his firm created 500 bridge designs.
