Mike:
I actually walked across in in 1971. The dual gauge was still in place. The D&RGW had left a long string of stock cars on a segment of the valley line just north of the highway and they were brought across a few at a time with idlers when the scrappers needed them. The bridge (or trestle) was so unspectacular that I did not remember much about it even though I walked over it. When I came back in 72, all the stock cars were gone and that segment of track had been removed and I assume the 3rd rail as well.