Enough details can be observed to give one an educated guess that this is the original bridge over Douglas Creek, between Columbia River and Vulcan.
This line was replaced in 1902 by the current line, still in use by BNSF.
See this location today.
Ted Curphey figured the spur below the bridge in the center, and then in the creek behind the bridge in the left of the image was a switchback. He put together a map: