I started thinking about the Conejos River Bridge and looked up it's origins.
Length 110'
Built 1887, located at MP 205 (don't know where that was (Royal Gorge Route?)
Installed 1917
Weight of structure, 150,000lb
Builder Edgemoor
Material Iron
So..... This bridge dates from 1887. Everything from narrow gauge 4-4-0's to standard gauge SD90's have been over it. Pretty amazing accomplishment. Imagine telling the guys as Edgemoor "hey do a good job on this one it will be around 130 years and will support locomotives the size and like of which you cannot even dream of".
1744 was the first SG steam over it in over 50 years.
Anyone know of another bridge structure of such longevity that supported such a wide range of loads?