5.56mm
If I lived in a desert, I’d prefer the train, so I could get out. LOL
If I wanted to stay, the train could bring me tanker cars of water, and clean unicorn farts for carbon-free fuel.
It could also bring me stowaway illegals to work for me, and keep up the golf course and resort.
The tanker cars of water would keep the everything green and growing; the unicorn farts would power the A/C and hotel for rich progressive environmentalist coming for the regular conferences to discuss energy and water conservation for everyone else.
/sarc