|February 2014 (37.94127 Degrees, -121.55907 Degrees) Washington Island Railroad Bridge|
The Woodward Island RR Bridge has concrete trestle approaches and plate girder/through truss bascule spans. According to the Bridgehunter, this is one of only 8 remaining bridges that use Hugo A.F. Abt's patented design. In this design the counterweight swings under the tall truss while lifting the plate girder span. This allows the approach to remain open under the counterweight. This odd design allows a replacement Abt bridge to be built on the same alignment in the open position facing the other bridge. Terry Koglin describes this solution for movable bridge replacement in his book, "Movable Bridge Engineering." I would imagine that the deck of the replacement bridge must wait until after the old bridge is removed.
Contra Costa County, California Bridges: Woodward Island RR Bridge across the Old River by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.