There's not actually a better explanation for why Snowpiercer takes place on a train than "the story the author wanted to tell depends on it" but it's still more solid than why all the vampires kept going back to high school.

This observation brought to you by the tagline on the promoted trend for the Snowpiercer TV show.

There is nobody on this planet who, without prior knowledge of the story, could read "There's only one way to survive on a frozen planet." and think, "...is it a choo-choo?"

Like, the world is frozen. Constantly wracked with snow and ice storms. And your only hope for preserving the species is that tens of thousands of miles of continuous tracks don't develop a fault anywhere on them while you're half a world away from half of them?

In-universe you can say the circumnavigational train system was set up before things got bad not as a survival mechanism, and was designed to be self-sustaining and self-maintaining in a way that made it possible to string things out. Also, things *are* breaking down.

But all of the priors that add up to the state of affairs at the start of affair, those that are explicitly stated, those that are implicit, and those that are never even hinted at, all exist in service of the story the author wanted to tell, which takes place on a train.

This is not even a criticism of Snowpiercer. Most sci-fi stories, most stories period but when you're making up technology it's kind of sharper, rely on premises that eventually come down to the axiom of "Well, this is the story we're telling."

E.g., Firefly has artificial gravity that otherwise breaks the level of technology realism and in no way relates to the actual power level of a ship because "one does not desire to make a floaty show" (and also budget).

Star Wars is fairly consistent that the thing that makes FTL travel tricky is information - in a galaxy the size of a galaxy, you need to know where you're going. You defend your hidden base by not sharing the coordinates, not by establishing a frontier.

And that's actually basically the best "hard sci-fi" thing about Star Wars - that you can have hidden rebel bases and entire mythical planets. Anybody with an FTL fleet can roll up to your door five minutes after you get doxed but you can stay hidden forever if no one talks.

But just as most of Star Wars work better as a fantasy or fairy tale than an explication of how things would work, Snowpiercer is way more of a parable than anything. https://twitter.com/arthur_affect/status/1260681582626525185

The only real "defense" for the premise is, again, that it's the story the author wanted to tell. A horizontally stratified society in a mostly closed system that *needs* to run forever but really actually can't.

Astrotrain Snowpiercer

Being A Choo-Choo
For No Actual Reason

Related: My "secret origin of Astrotrain" thread. https://twitter.com/AlexandraErin/status/652158052754284544

The marketing from a six-year-old point of view is a slam dunk, I have no argument there. TRAINS and SPACESHIPS. Yes. I'm right there. https://twitter.com/DaiMacculate/status/1260685445421248512