Expanding my circles around my new temporary home in Palo Alto gives new sensations weekly for a railroad guy like myself. Passing the San Francisco bay on highway 84 gives a spectacular view over an apparent disused railroad bridge, just waiting to be explored.
The bridge was built by the Central Pacific Railroad in 1910 to create a shortcut between the southbound SP mainline from San Francisco to the other side of the bay. Eastbound traffic could using the bridge shorten the route by 22.5 miles compared to passing south of the bay. This bridge to me represents the golden era of American civil engineering, really conveying a sense of determination where cost is a secondary factor. The bridge was designed for two tracks but given the trestles and narrow track bed on both sides, it appears like these plans were never realized.
As San Francisco's importance as a port diminished after WWII and port operations gradually moved over to Oakland, where also railroad transport was on the decline in general, the need for the "Dumbarton cutoff" diminished as well. However, the Dumbarton corridor was opened to traffic until 1982, but when the traffic ended, the swing spans were welded into permanent open positions. The approaches to the bridges are timber trestles and the one on the western side was destroyed by an apparent arson fire in 1998. There are plans to reopen the route for commuter passenger services, but given the thirty years of decay together with California's fiscal problems and the general skepticism for public projects here, it seems to me unlikely that any consensus will be reached in a near future.