I will need to dig through my photos. I believe Ron Nixon had this in his collection. Trying to recall if it was damage from a snow slide. Have Ron's letters, somewhere.
East Willow and West Willow creek meet above where this was at. The passenger train had been bucking snow with helpers and periodically got a driver(s) off the rail. They backed down to rest the crew and a portion of the train was on the "S" Bridge when the snow slide came down and took out a portion of the bridge. Whether it originated in East or West Willow is of little concern because both drainages are very steep. No deaths on the snowslide. One of the drainages, after a steep hike, contains a meadow and the final ascent to the top and ultimately Stevens Peak. I believe this meadow is the one referred to in Ruby El Hults' book where the 1910 fire burned over the Michaelsons' crew. Hiked up there in 1973, early June, and met snow at the meadow. Climbed hand over hand at a 65 degree angle to the lake. Big ice berg in the lake. Came back down on my butt on a snow field down the West Fork. The hike to Stevens Peak is a woo woo woo but rangers made a daily trek to spot fires in place of fire lookouts.
Barnard-Stockbridge Collection, University of Idaho, Special Collections in the Library section of the website may has a view of the wreck from a different angle. Search "S" bridge wreck in the Barnard-Stockbridge Collection.
