Graphene is likely to cause negative environmental impacts if spilled

I think they heated it up then dropped it into liquid oxygen.

Ironically this is similar to the danger posed by low-level radiation releases (except exhaust is far more dangerous), except everyone freaks out when their local radiation levels are 10% above baseline, but nobody cares when local pm2.5 levels are 20% above baseline. (They do notice at 1000%, to their credit).

How do you imagine this working, pray? "Build lots of trains" I expect to feature prominently in any response you might make, and that's fine as far as it goes. How do you envision their cargo making its way from there? Cities depend on endless fleets of grumbling, farting trucks, which of course no one loves, and presumably by now you'll have scrapped them all and had them melted down for their steel. But that leaves tons upon tons of goods -- tons and tons just of food and drink, every single day. How d'you plan to shift all that? Do you envision streets full of carts and horseshit? Hand-drawn wagons and barrows? Coffles of laden, staggering slaves?

Or do you instead fantasize about what in the early Cold War was called "decentralization" -- put short and simply, the enforced diaspora of millions upon millions of city dwellers into a countryside which has neither need nor desire for their presence, to say nothing of places to put them all? Oh, that'd go so much better! I'm not sure who'd hate whom worse, or where the riots would most likely start, but I'm sure that scheme would make for a stretch of history delightfully full of incident -- the sort of thing for which future high school students will find it actually worth keeping their eyes open in class, assuming future high schools reverse our modern degradation at least to the extent of resuming proper instruction in history.

Or have you some other fantastic scheme? Honesty compels me to admit that I have never yet encountered a utopian theorist whose fancies bore up under anything remotely resembling rigorous criticism, to say nothing of reality's much harsher judgment. But, while no longer young, I'm far from dead yet, and I don't imagine I've heard everything there is to hear. Perhaps you will astound me.