There would have been four large bridges before Green River and a 560 foot monster across the Green River itself. They sent several months surveying the route and there is a map in the Polley book, but it lacks detail.
i'm having to improvise as the book blithely states the route traveled above the river on the bluff, this is not exactly flat. It would in my opinion been a costly to construct as the route over baxter pass, although much less maintenance would have been needed as it would have been way above the flash floods that regularly washed away trestle footings .
i was hoping Mr Polley might have published some more details here than was in the book, looks like he didn't ,so i'll just have to make judgements based on the way they constructed the rest of the route .