In December 1917, the bascule railroad bridge that spans the Lake Washington Ship Canal near 34th Avenue NW in Ballard is completed. The bridge spans the canal on the Puget Sound side of the locks. It crosses the canal 45 feet above the water (designed to eliminate as many bridge openings as possible) and is one of five bascule bridges spanning the ship canal. (The others are the Montlake Bridge, the University Bridge, the Fremont Bridge, and the Ballard Bridge.)
Bascule bridges have lift spans that open and close like teeter-totters. The lift spans have counterbalances that dip into a housing (the bascule pit) when the span is open. The system of counterbalance and leverage enables them to stay open in any position. The railroad bridge differs from the other bascule bridges on the Lake Washington Ship Canal in having only one lift span.
These bridges, and later the high Aurora Bridge (George Washington Memorial Bridge, 1932) and Lake Washington Ship Canal Bridge (Interstate-5, 1962) replaced various low bridges crossing the lakes, bays, small canals, marshes, and ditches on the route of the Lake Washington Ship Canal, which opened on July 4, 1917.
