The IC branch between Paducah and Louisville is now the Paducah & Louisville Railway. It, along with US-62/641 used to go across the crest of the Kentucky Dam. As part of the work to build a 110x1200 foot lock, the road and railroad were moved off the dam by building bridges for them downstream from the dam in 2009. (The current lock is 110x600.) There is still a public road on top of the dam to access a Visitor Center that was remodelled in 2012 and is supposed to be open 7 days a week but that was "closed until further notice" the day we visited.
I was so focused on taking pictures of the dam, that I didn't bother with the bridges. Fortunately, the Bridge Hunter link above has lots of pictures. Below you can see that both the railroad and the road bridges used steel girders across the spillway. The upper beam is the road bridge and the lower one is the P&L bridge. Comments on the Bridge Hunter page confirm the steel is brown because it is CorTen. That means the surface rust will protect it from further corrosion. That is, these bridges don't need to be painted and are thus low-maintenance. I was taking this picture to capture the two tows. The tied-arch bridge in the background is I-24/69.
Turning to my right, you can see that the road bridge continues to use steel girders but the railroad switches to a 505-foot truss to span the shipping channel leading to the lock.
[Update: I spent some time looking for a new URL. No joy.]