BNSF Ship Canal Drawbridge
N 47° 40.020 W 122° 24.124
10T E 544889 N 5279462
Railroad Drawbridge Spanning the Salmon Bay Ship Canal
Waymark Code: WM243Y
Location: Washington, United States
Date Posted: 08/31/2007
Views: 85
Salmon Bay Waterway, Bridge No. 4 was designed by The Strauss Bascule Bridge Co. of Chicago Illinois in 1912. Construction of the structure referred to as a "Strauss Heel-trunnion Bascule Bridge type" on GN blueprints began in 1913 by the Fort Pitt Bridge Works of Pittsburgh, Pennsylvania for the Great Northern Railway. The Bascule designed drawbridge provided a vital link for The Great Northern Railway's Cascade Division, thus connecting Seattle's gateway with Canada to the North and St. Paul to the East. GN records describe the railroad's requirements: "To secure double track on improved alignment, free from grade crossing and to comply with requirements of the U.S. engineers at the crossing of Salmon Bay Waterway, the level of which is to be raised in connection with the Lake Washington Ship Canal."
A 500 ton concrete counterweight is used to lift the 200 foot Bascule span. The counterweight itself was designed with doors located on the south side that open to its interior where heavy rail could be removed during the summer months to compensate for the ties that had dried out from the winter rains. The lift span, the 165 foot truss span to the south, and plate girder approaches on both ends give the bridge a total length of 1,145 feet. At extreme low tide the bridge sits about 50 feet above Salmon Bay's waters. The two towers located on the North and South ends of the superstructure were add ons for electric public utility and signal lines but are no longer used.
Bridge Type: Drawbridge (Bascule Bridge)
Pedestrian Traffic: no
Bicycle Traffic: no
Vehicular Traffic: no
Railway Traffic: yes
Built: Not listed
Span: Not listed
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Visit Instructions:
Take a picture of the bridge and record the exact coordinates where the picture was taken.