@sj_zero
> When it comes to climate comparisons, I think it isn't so simple as "trains use less fuel per passenger"
Agreed, and this is where the rubber meets the road. If you accept the greenhouse effect, and that the planet is warming, then it's worth investing in things that aren't financially efficient, as long as they reduce carbon emissions.
So the key question is, would a China-style fast train network in North America reduce carbon emissions?
(1/?)
If they were electric trains, and adding enough renewable generation to power them was part of the project, I can't see how they wouldn't. Yes, that would require some *big* investment.
But both the electrification, and the upgrading of tracks to allow faster speeds, can be rolled out in stages, as it was in China.
(2/?)
Remember we're not talking about starting from scratch here. An extensive track network already existed in China before they started electrifying and upgrading tracks for fast trains. As it does across North America;
US;
https://stb.maps.arcgis.com/home/webmap/viewer.html?webmap=96ec03e4fc8546bd8a864e39a2c3fc41#!
Canada;
https://rac.jmaponline.net/canadianrailatlas/
https://ontheworldmap.com/mexico/mexico-railway-map.html
Every piece of track electrified or upgraded adds value to the network as a whole.
(3/?)
It does seems logical to start with the most populated areas and work out from there. Which explains your observations about the correlations between high population density and train corridors. But so does the fact that causation goes in the other direction too. A small town on a new or upgraded train line between two major centres can become a much more attractive place to live, when some of the trains stop there. Plane links can't do this.
(4/?)
Having said that, do I think there should be a train linking every population centre? No. You're right that mass transit only makes sense for routes where it is (or likely will be) common for a large number of people to travel. There are journeys where trains can't replace buses, private vehicles and active transport.
But based on what I saw in China, I think they can and should replace most (if not all) domestic air travel.
(5/?)
I do think that railways lines themselves are a natural monopoly. If they are owned by for-profit companies, and especially if those companies can be bought out by those invested in car/ oil/ airline/ hyperloop etc, is unlikely to result in passenger-friendly development.
So railways either need to be (re-)nationalised, or heavily regulated to make sure decision-making prioritises the interests of passengers, and the network as a whole.
(6/6)