San Joaquin County, California Bridges: State Route 4 (Borden Highway) across the Middle River

February 2014 (37.89072 Degrees, -121.48932 Degrees) Middle River Bridge

Traveling east on State Route 4 (the Borden Highway) I drove up a rise and came upon the Middle River Bridge (29 0049). The bridge is composed of two short pony truss spans on the east side, two big through truss spans across the channel, and a pony truss span on the west side of the river.

After doing a little research, I decided that this bridge used to be a swing bridge, almost identical to the SR-4 Bridge across the Old River that we studied in February. The bridge was built in 1915 but in the 1990s Caltrans converted it from 'movable' to 'fixed' and also strengthened it. I'm wondering if they also raised the bridge and and perhaps widened it (although the through truss strongly resembles the swing spans before the bridge was rebuilt).

The bridge crosses the Middle River where it meets Trapper Slough, and so State Route 4 jogs to the left after crossing the river to follow the slough. 

San Joaquin County, California Bridges: State Route 4 (Borden Highway) across the Middle River by Mark Yashinsky is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.