Whata great bridge. Isn't this where the Olympian went off the rails in a wicked rainstorm that flash-flooded the stream bed?
Kurt- No that was a much different style of smaller bridge/trestle over a streambed which is usually almost or completely dry. At bridge AA-438 on Custer Creek, near Saugus. Boxcab E50
I only see three spans in the photo, so am uncertain. The only bridges I can think of start just west of (bridge BB-8, Yellowstone River) Fort Keogh, and on east of Miles City. But those are all four spans. At first I though of BB-8, but it's been so long since my last explorations... Boxcab E50
Miles City strikes me first, but I have never seen it, so I donno. Might be another span out of view.