Friday, January 10, 2020

CSX/L&N and NS/Sou Bridges over Tennessee River in Knoxville, TN

NS/Southern: (Bridge HunterHistoric Bridges3D Satellite) 1850s stone piers for a covered wood span, but now with 1903+ trusses
CSX/L&N: (Bridge Hunter; Historic Bridges; 3D Satellite)

NS/Southern



Street View

Street View

CSX/L&N


Aaron Bryant posted five photos with the comment: "The Louisville & Nashville, bridge over the Tennessee River, in Knoxville, Tn. I'm not sure when it was constructed, but it's interesting that it's painted orange in honor of UT, which can be seen in the distance. Photos taken: 12/28/19."
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I don't think that is orange paint. I think that is rust!
Street View

Aaron Bryant posted a couple of the photos again.
Jeff McNally: I helped paint it in 1986. It will never be painted. CSX says that it’s cheaper to replace still when needed. Anyway great picture. I’m retired now.
Ray PL: I understand the physics of the center truss bridge, but what is the reason/advantages for the two that are inverted?
Dennis DeBruler commented on Ray's comment
A deck truss generally has the advantage of using shorter piers than a through truss. I included another photo by Aaron that shows how the far, non-transition pier is shorter.
Looking at these photos, it just now occurred to me that for a deck truss the steel girders that hold the rails probably help provide strength for the top chord. The top chord of a truss is in compression and the bottom chord is in tension. Steel is stronger in tension than it is in compression. Thus it needs more material to handle compression loads.


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