Good guess, but I've now learnt that the bridge depicted on my photo is from the construction of nearby Maze Road Bridge on CA 132 (Maze Blvd), crossing the San Joaquin River. There's currently no recording of this bridge at Bridgehunter.com. The bridge was built 1935-1937, and was inaugarted in August 6, 1937.
Attached is a picture which is believed to be East Tracy OH during construction in 1936, received from my great uncle who is likely to have been employed as carpenter at the bridge construction. Bridge engineers of Tracy has confirmed that the picture is consistent with East Tracy OH. The boy on the picture is my great uncle's step son. Incidentally, East Tracy is in advance stage of being replaced, full documentary including pictures and maps can be downloaded from this web site: http://ci.tracy.ca.us/documents/11th_St_Bridge_Draft.pdf
Borje Lundvall, Karlstad, Sweden