Elon speaks on a topic for which he has few apparent qualifications, the classic mark of a fool, April and otherwise:
An example of idiocy, as the “trust the experts” crowd says? The experts themselves disagree with Musk. A Florida-based bridge engineer:
(My comment on the above: Sell the old truss on eBay? “Dropped once. Never snapped.” (see also, re: World War II, “French Rifle for Sale: dropped once, never fired”.))
I wonder if both Elon Musk and the Florida engineer could be correct.
If you want to build something to last 50 years and have a big safety margin and you don’t care how long it takes to build, the civil engineer is right. What if it needs to last only 10 years (while an adjacent replacement is built using conventional techniques) and you’re willing to compromise on aesthetics? Maybe Elon is also right. Pick up and reuse as much of the old bridge as possible. Do a new structural analysis of the old design to see where doublers and other structural enhancements are needed given possible weakness of some of the elements. Instrument it with strain gauges everywhere. Then patch it up and let all of the self-driving truck companies pull heavy trailers onto it. Check the strain gauges. If everything is consistent with the analysis under a real-world load, open it to cars, but not heavy trucks. In the #AbundanceOfCaution department, maybe close the bridge if there are exceptional winds (1 or 2 days per year).
Given the fact that it is possible to drive around this bridge and the American hunger for perfect safety and security and the construction industry’s reluctance to do anything unconventional, my suspicion is that the Florida engineer is correct and Musk’s idea could never work in practice. But Musk’s idea might be a good one if there were more urgency regarding the rebuild, for example.
Where would we be without Elon’s perfectly timed zingers to save the day & motivate all the world’s experts into commenting? They would still be debating starship stage dimensions without our fearless attention seeker.
Does not look like a good idea to reuse steel submerged into highly corruptive sea water for critical infrastructure. My understanding that the bridge is needed manly for business use, ie hauling truck trailers over it.
Temporary bridge can even made out of wood. There is still an operational “temporary” wooden railroad bridge in operation (or was until recently) built quickly over west Siberian rivers during WWII to facilitate cargo and troops movement.
perplexed: The steel was painted to prevent corrosion, right? How is a brief dip in the water near the top of Chesapeake Bay (not seawater, though it can be brackish) followed by a freshwater rinse going to have ruined it?
Just throwing ideas. Is it painted on break lines too? My comment is inspired by disabled abandoned Russian tanks in Ukraine. They seem to rust in a week at most left to elements (maybe after light fire). On the other hand my pick-up undercarriage looks rusted, with no effect on truck capacity to haul.
However and whenever the Francis Scott Key Bridge is rebuilt, it’s the perfect opportunity to rename it to the George Floyd Memorial Bridge.
Are large pieces of steel hard to come by? Is that really the bottleneck? The only similar (but much smalller) incident I’m familiar with is when part of the “MacArthur Maze” caught on fire and collapsed one night. https://www.infrastructurereportcard.org/2009/case-study/macarthur-maze-repairs.html
California infrastructure work usually takes FOREVER, but this was interfering with traffic at a junction between several freeways and a major bridge. It was astonishing how quickly they fixed it (a much smaller project than a whole bridge) It turns out that the state offered contracts with big bonuses for speed and heavy liquidated damages for further interruption of traffic, and lo-and-behold, it was done in the blink of an eye. It led me to believe that infrastructure work in the U.S. is dragged out intentionally. (not sure why) The seabees (Naval construction battalions) are famous for building large things practically overnight using the same technology contractors use to do it over months or years, for another example.
I don’t know anything more than Musk does about bridge building, but I doubt un-twisting angle iron on site is more efficient than just ordering new angle iron from a steel mill. (We do still have a few steel mills, right?)