Historic Structures

Willamette River Swing Truss Railroad Bridge, Portland Oregon

Date added: July 30, 2021 Categories: Oregon Bridges

The network of Vancouver-Portland railroad bridges across the Columbia River was the first bridge link between Oregon and Washington States, crossing the Great River of the West, and providing the necessary rail link between the four major railroads which met in the Portland-Vancouver area: the Great Northern (GN) and Northern Pacific (NP) railroads and their subsidiary, the Spokane, Portland and Seattle Railway Company (SP&S) from the north side of the river, and the Oregon Railroad and Navigation Company (Union Pacific) and Southern Pacific Railroad from the Oregon side. Until the new bridges were built, the interchange of trains and cars was made by ferrys at Kalama and Vancouver, Washington. A highway bridge across the Columbia River, Interstate Bridge (US 99), would not be built until 1917.

The Vancouver-Portland bridges run in a generally north-south line from Willbridge in northwest Portland, across the Willamette River to the North Portland peninsula, through the Portsmouth Cut across the peninsula to Columbia Slough, across the slough on a short single span and along a railroad fill-dike dividing Smith and Force (now Vanport area) lakes, low flood plain areas of the Columbia River, to the Oregon Slough (North Portland Harbor), across on the Oregon Slough Bridge to Hayden (Shaw) Island and along another fill, replacing the original Hayden Island Viaduct, to the Columbia River and the Vancouver Bridge. The total bridges, causeways, and cut complex is about 4-3/4-miles long from the north bank of the Columbia River to the south bank of the Willamette River, The bridges are comprised of 21 through truss bridge spans, three center swing draw spans, and three deck plate girder spans. The Willamette River Draw Span is the longest of the bridges, measuring 521 feet long. The Willamette River's four fixed through spans are identical with the six of the Vancouver Bridge, each 265 feet long. All piers are similar and constructed of granite ashlar faced plain mass concrete on timber piling or mass footings. Timber caissons were used to build the piers. The through truss fixed and draw spans are of the Pennsylvania (petit) type of Parker truss.

There are two systems of numbering for the bridges. The system of numbering used by the Coast Guard and the USGS identifies bridges by river mile distance from the mouth of the river which thus identifies the Willamette Bridge as No. 6.9 or 7. The railroad numbers the bridges in miles from Portland's Union Station, with the Willamette Bridge identified as No. 5.1, Columbia Slough Bridge as No. 7.4, Oregon Slough Bridge as No. 8.8, and the Vancouver Bridge as No. 9.6. The Vancouver, Washington terminal is No. 10.

The railroads from the east and south, and river traffic (including ocean-going vessels and riverboats) made Portland a shipping and banking center of the 19th century Pacific Northwest. Construction of a Washington-Oregon Columbia River channel bridge began in 1890, "...only the pivot pier for the draw-span had been completed, and a few piles had been driven for the draw-rest pier, between the pivot pier and the shore." After the successful Lewis and Clark Centennial Exposition of 1905, the city began a period of rapid growth which defined its pattern for the next half century. When, in 1902, railroad magnate James J. Hill announced that the Northern Pacific Railway Company planned to bridge the Columbia River and to dig a tunnel under North Portland's Peninsula district, the city was excited by the prospect of more jobs and economic development. Such a bridge connection was the last link in completing the network of railroad lines throughout the Portland-Vancouver region, the Columbia and Willamette river basin areas.

Mr. Hill abandoned the idea of a tunnel through the peninsula, and proceeded to persuade the reluctant city to permit the SP&S to excavate a cut across the North Portland peninsula, a decision possibly influenced by the alternatives proposed in a 1905 report by the bridges' chief engineer, Ralph Modjeski. Despite the fact that the railroad offered to construct four street viaducts across the cut, Portland Mayor Harry Lane vetoed the ordinance for the cut on the grounds that it was a land giveaway, a defacement of property, and a visual blight. However, business interests prevailed, and the Mayor's veto of the ordinance permitting the cut was overriden by the City Council.

At the time of the bridge's completion, and for the next thirty years, the Port of Portland's drydock and ship repair facilities were located on the north bank of the Willamette River just west of the bridge. The drydock facilities were moved to Swan Island after World War II to the site of the Kaiser shipyards.