Lost Mare Island Causeway SOC Bridges over Napa River in Vallejo, CA

1919: 2-lane wood SOC bridge

1935: 3-lane concrete SOC bridge, this was a WPA project

1980: (Bridge Hunter; 3D Satellite) this increased the navigation channel width from 75' to 100'.

The causeway is now named "Ernest D Wichels Causeway," who was the only person to see all three bridges dedicated.

I wonder how much work the navy still does here.

SOC = Strauss Overhead Counterweight

Mare Island Museum posted
[An extensive history, it is well worth a mouse click or screen tap.]
Douglas Butler shared
Credit to Mare Island Museum: The Mare Island Causeway Shipyard Bascule Bridge is a Strauss Overhead Counterweight Trunnion Bascule Bridge designed by the Strauss Bascule Bridge Co. and built in 1935 by the Barett Hilp. This bridge crosses the Mare Island Strait in Mare Island and Vallejo, CA. Used by Road and Railroad Interurban, Sacramento Northern Railway, San Francisco & Napa Valley Railroad, Napa & Calistoga Railway, and US Military Transportation, the bridge was the second bridge built and was replaced with a vertical lift bridge in 1980.

Mare Island Museum also posted
Mare Island Causeway Bridges #1 and #2
[Note that the first bridge also used a SOC design.]

John McCory, Aug 2022

Street View, Aug 2022