This is a world I have in a post-apocalyptic setting, called "Last Train To Anywhere". Decades after a nuclear war, one which expanded rail systems, especially after the formation of America's seventh military branch: the Rail Force, all militaries and governments have been disbanded. All that remain are private town-based and city-based defensive security companies, as well as teams and syndicates of raiders, who take what they want when they want. There are also teams and guilds of mercenaries, both good ones and bad ones. Many individual teams and guild-affiliated/syndicate-affiliated teams of both mercenaries and raiders utilize trains. One such good non-guild-affiliated team of mercenaries utilizes an old tank engine that they call "Little Boy" (no, not like the nuke). The first boxcar (the Santa Fe one) is for personal storage like for their weapons and other things, but not food. The second boxcar (the Southern Pacific one) is for cargo carried for jobs, usually shipping jobs. The yellow coach has been modified with a small command center and a few bedrooms. The excursion car is basically an observation lounge. The tiny logging caboose at the back contains a small bedroom that nobody wanted due to its size until their newest member, a tribal dalmatian girl named Lula, whose entire tribe (save for her, obviously) had recently been wiped out by raiders, joined them. This team only takes jobs that fight for the greater good.

Fun fact: I actually got that engine yesterday at my train club's annual train show!