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> “The existence and practical effects and consequences of metal fatigue’s been known and understood since the 30s and that was definitely so post WWII. This bridge was built in ‘67. They’re still passing the BS about how they didn’t know.”

Yes and No. Fatigue was not really known until metal airplanes. It was not well known in the aviation industry until after WWII — after several fatigue failures. It was not used elsewhere because it was expensive to design for that (mostly, it could not be designed for — parts were made and tested to failure) and most things were heavier than airplanes and did not need to worry about fatigue.

The information on fatigue was filtering down to the highway industry in the mid to late 1960’s. I had some of the early articles written on it at the start of my engineering career. A lot of it was VooDoo. I saw a newer article on it a while back that is much more usable. Over-the-road highway trailers were just starting to get light enough back then that fatigue started to be a problem — particularly in gasoline tankers (they went from a tank on a frame to a monocoque structure with the shell actually carrying the load and they also became totally welded at about that time).

Fatique information had not made it to the bridge industry even then. They had a bridge at Sioux City over the Missouri river that was built sometime in the 1970’s or so that started fatigue cracking within a year of its completion. It had to be replaced in just a few years.

Back then, the engineers thought that bridges would never see enough cycles to cause fatigue cracking (at least, that is what they are teaching in bridge inspection courses). Obviously, they were wrong. A combination of using calculators and computers to pare down the weight to the absolute minimum and the increased use of welding was the major causes (note that riveting and bolting structures, which is rarely used now, means fatigue cracks are less likely to start and will end at the next joint instead of cracking completely through the structure).

As far as you statement that politicians would NEVER fail to correct a problem — you have obviously never dealt with politicians. Unless you can give them and EXACT date and time when it will fail, they are not interested. Sometime soon is not good enough. Read my “All About” page here if you want to read about my experiences on that.

"Yes and No. Fatigue was not really known until metal airplanes. It was not well known in the aviation industry until after WWII "

Short... Yes, one of the first engineering studies was done by a Boing engineer regarding airframes. It was shown dramatically that even mild steel does that, when a 30 y/o ship slit i half. ~ in the 40s.(CRS) The process itself though is a solid state phenominon that was studied in physics, but for different reasons. I just gave the WWII date, because the subject occurs in 50s era metallurgy and engineering books. I realize that there are different quality and levels of texts and that more detailed knowledge doesn't spread far.

Yes, I have dealt with politicians. I can't say much now, except they are just people. It's like advising on critical car work. The car owner has to make a decision regarding the mechanic's claims. The mechanic may not be able to say when the wheel will fall off, but he can make the case as best he can that it will in fact do so. The pol must make the decision for the community regarding public property. Something like a bridge is simple. If the engineer sees somehting like a bridge containing fatigue cracks, or even unsafe stress levels, his duty is to inform both the exec and the public, because it's public property and safety involved. The public certainly understands bridges and "public" buildings collapsing, and anyone that is a pol certainly should.