Jason - I knew it was trouble when I saw you respond to this first. Yes, It's the first bridge across Boulder Creek on the C&N. Until I saw this photo, the only one I remember seeing of this bridge is this one from my collection, which isn't as good a view of the bridge itself (although you can see the C&N facilities and Climax No. 2 in the background):


If it wasn't for this photo of the train on the bridge (with some distinct features that show in both photos), I would not have been easily convinced that it was this bridge, or even on the C&N (although a street view from Google Maps nearby on Canyon Blvd shows the same hills in the background).

The location is about here. It looks a bit different today.