Why US Bridges Are Falling Apart?

Over 4000 bridges have been replaced in the US in the past 5 years. This number is only a fraction of the total number of structurally deficient bridges in the US, which is 43,000 bridges that require serious maintenance and attention, with many due for replacement. This exposes a huge weakness in US bridges, dating back to the 1900s.

[@tomfuelery2905]

Hernando Bridge is in Arkansas and Tennessee connecting West Memphis and Memphis.

[@Paul_C]

Because they are not safe.

[@divineantiwokegangster]

i hope terrorists will not destroy those bridge cables

[@zo62]

1

[@thomasrengel5577]

1) You gloss over the problems of cable-stayed bridges before 1950.
2) Structural deficiencies in metals had to be solved in the 19th century. Steel replaced iron only after steel had become reliable.
3) The truss era in America had a MAJOR complication: American engineers didn't trust RIVETED structural joints unlike the Europeans. Americans used pin-connected joints regular to WW1-era and even later; this gives American truss bridges their tinker-toy/erector set look totally lacking in Europe. One consequence of this is that for American truss bridges tension and compression members look distinct from each other--unlike European designs.
4) Yes, American and European engineers DID trade insults whenever a bridge collapsed--when Dundee's Tay Bridge collapsed in 1879 (75 dead) Americans Got Even for British remarks about the Ashtabula OH collapse of 1876 (80 dead).
5) Regarding continuous trusses which carry stresses across piers unlike how a simple truss "works" solely between its two piers, HOW to properly calculate carrying stresses across piers wasn't figured out until about WW1. The Sciotoville RR Bridge over the Ohio (1916) was the first BIG continuous truss in this country and showed what could be done with the design. Of course if anything happens to just one pier ALL spans will come down. The Key Bridge collapsed EXACTLY as Statics said it would once one pier got weakened!
6) Regarding aesethetics---I think cable-stayed designs are banal and ugly---glorified plate girders basically. Trusses are NOT intuitive and are major design achievements. Messrs Howe, Pratt, Warren, Whipple, Post (for a weird one!), Wagram, etc. all at work. (All were bridge designers of particular types of truss.)
7) Lastly, "Deficiencies" are often political ploys for ginning up bridge construction projects for contractors and unions. These are non-structural deficiencies. There was a ruling that all bridges should have 4-foot parapets so any bridge like to Castleton-on-Hudson Thruway bridge is "deficient" merely for having railings
instead of concrete walls!
8) You need to learn how to speak English better. And lay off being Biden's stoolie. You clearly took sides in our election!