Let me take a shot at this:

I can try to figure expenses from my previous experiences. I don't know what the UP used for stringers and posts so will figure on the old NP/BN timber sizes. I am assuming 5 post bents.
Looking at the profile for that section of track and not knowing exactly which bridge was lost, I see that many are 20 span structures and will go with that and 15 foot spans.
I don't believe a bridge of that height would have had diagonal bracing or line girts, but I have figured those also.

Stringers: 2 each 3 chord sections 10" x 18" x 32', 60 pcs @ $701.28
Posts:12" x 12" x 28', cut to length, 126 pcs @ $398.50. This also includes the 21 pcs needed for sills.
Caps: 12" x 16" x 20', 21 pcs @ $310.72.
Sway braces: 3" x 10" x 24, 42 pcs @ $55.32.
Tie spacers: 4" x 8" x 20', 30 pcs @ $66.33.
Bridge ties: 8" x 8: x 12', 180 pcs @ $50.22.
Diagonals and girts: 6" x 10" x 32', 80 pcs @ $183.36.

I am showing that each post on each bent will take a full 28' stick. Obviously, the short bents will be able to get more than one post per stick and in some cases many posts, but for figuring the maximum costs I am using one full stick per post.
The total timber costs amount to a little under $127,000 using costs of timber in the mid 1990s. If the price has doubled since, we have $250,000 and change, the hardware would not amount to much over $5,000 and add the cost of rail which varies, figure $6000.
I don't know how the state would figure the labor and equipment costs, but even figuring $10,000 per bent, labor and equipment would be $210,000.

Unless I have been out of the loop too long and my material prices are too low, my estimate is still under a half million. Increasing the capacity of the bridge by adding a fourth stringer chord would bring the cost up to $724,000.
Double everything to cover the price differences and shipping costs for material and environmental issues and the cost is around 1.5 million and I think that is way out of reason.
As I stated previously, I have been out of the loop for a while and maybe timber prices have even tripled since the mid '90s.