Tornados like this one are a statistical risk you take by living in that part of the planet. We can't engineer practical structures that can survive them. The only mitigation is to live somewhere that doesn't have severe tornados.
There's a question of whether or not its worth it, especially the maintenance costs. But if tornadoes in the region only give 15 minutes of warning, then a very strong "safehouse" of some kind is probably the best option.
Maybe the group would get trapped in the safehouse and be nearly starving after 2 or 3 days. But the rescuers might find them in time?
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I'm not necessarily saying that its easy to build a 110-person bunker. But if you have 110 workers, then surely that's something you need to consider as a preventative / safety measure?
The devastation is awful but at least they got out with their lives. They can rebuild.
The building was roughly 340'x300', if the shelter was in the center the longest inside distance would be 200' but they also had material storage outside, up to 380' away as the crow flies(aka. gonna be longer).
They will be literally running for their lives but Bob is 45 and has been smoking since he was 15. Jim is in a wheelchair.
Yes but if they're at work, the employer is responsible for their basic safety. Asking them to sit in a sheet-metal-on-slab building during an EF3 storm is neglectful.
Sending them home to shelter with their families, whatever they do there, would maybe have been the better plan.
The house does not need to survive for the humans in it to be safer then if they were in a sheet metal box with no basement.
I think that should be up to the employees to decide, not their manager, and sure as hell not you.