It makes sure we calculate the loads correctly and use appropriate materials. You can't fix a bad design.
The Arkansas bridge that has been in the news lately probably would have collapsed if it wasn't for the F.S. https://www.ardot.gov/divisions/public-information/40-ms-riv...
No, it make sure that nobody dies when you calculate the loads incorrectly and use inappropriate materials.
Design errors
Probabilistic nature of the loads applied.
Material defects
Fatigue
Deterioration
For the impeller in a rocket turbo pump the service life is like 5 minutes. For the impeller in a hydro electric dam it's 50 years.
The other thing that one of my professors pointed out was that 80% of engineers end up designing once off designs. Where the NRE cost is a lot more than the material costs. Shaving the safety factor is false economy.
Because of goal of civil engineering is building man made objects with public safety in mind.
You need to know that something is redundantly safe, and which parts.
The factor of safety is above and beyond material variance. You calculate the worst case load combinations for that component, then you check your factor of safety. Civil engineering is relatively conservative in its estimations for everyone's safety.
In my experience serviceability requirements (like reducing uncomfortable deflections that dont threaten the safety of the structure) often govern, rather than the ultimate capacity.
It's fascinating to me, and I feel like over-spec'ing certain chokepoints in infrastructure makes sense like this.
An unnecessarily strong castle takes you more time and resources to build.
A slightly too weak castle means you die, your family dies, and you lose all wealth and power.
> A slightly too weak castle means you die, your family dies, and you lose all wealth and power.
You're really glossing over a lot of important concerns here. There are many, many ways to lose all your wealth and power, and lots of them might have been avoided if you'd had a few more spare resources.
Most spectacularly this is seen in Cathedrals, but castles, certainly some castles, definitely show this. I would argue pretty much everything the Romans built is more than a little overspecced, certainly at construction time (do you really need 3 story POOLS, meaning pool on -1, pool on ground floor, pool on first floor, pool on 2nd floor buildings ? Yes the higher ones were apparently rented out to very rich Romans, or more often provided as favors to them, so there was some function, but ... come on. They were constructed to mostly look very convincingly to be 3 story pools without actually being that. Despite that, none of the buildings survived for very long. But "over the top" can be said about many Roman structures, from the Pantheon to the Aya Sofia)
So having an unnecessarily big infrastructure project has it's own advantages that actually increase your odds of survival, and that didn't start with the space race.
This isn't really compatible with anything I know about the middle ages. Can you show someone of the time writing or otherwise demonstrating that he doesn't want the cathedral, but he's afraid of what the population will get up to if they're left idle?
This happened recently in Italy: https://www.bbc.com/news/world-europe-57219737. "Engineers" didn't consider the safety brake essential (i mean, why do you even need it?), and Murphy took his chance.
It seems like they’ve decided that the support cable was functioning after the main cable broke.
[1] https://www.nbcnews.com/news/world/blame-italy-cable-car-dea...