[cantankerous]

China's population is concentrated in one part of the country. That makes it easier to serve them more efficiently with mass transit. This isn't true for the United States. The population resides on the coasts, which you can serve with high-speed rail, but connecting the two coasts with the inland population centers via rail is a much, much bigger project.

[melling]

Yes, this excuse has been given for the past 50 years. Usually, in reference to Europe.

That might explain why they’re building 25,000 miles of high-speed rail in China, but it doesn’t address why the US has zero.

You’re being sort of vague with the numbers of course.

If you actually look at population densities in Spain, for example, and compare them to California or New York, what do you think we’d find?

For some reason, people like yourself want to average Montana, North Dakota, California, and New York. The US does not have a uniform population density.

[vonmoltke]

People also want the federal government to fund the construction of this infrastructure, which is a very hard sell (and possibly unconstitutional) if you don't average all of those states in some way. Most of the opposition to Amtrak and existing infrastructure projects like the Gateway Project is coming from those states, who don't see improving rail service in the Mid-Atlantic and New England as something they want their tax money spent on.

We need to fix that problem, and that means not simply writing them off as irrelevant because of their lack of population. Australia is likely facing the same problem.

[melling]

The federal government funded the highway system.

There are 350 million Americans. Do you know who pays most of the taxes to the federal government? It’s not the people in the mid-West.

https://en.m.wikipedia.org/wiki/Federal_tax_revenue_by_state

[Gibbon1]

I tried a simple estimate on how much a HSR line would cost from Chicago to Denver. About $20-30 billion. It's a 1000 miles of flat nothing, so it's cheap per mile.

Chicago --> St Louis --> Kansas City --> Denver is about 1000 miles.

[anoncake]

Building a railway from coast to coast has already been done in the 19th century. An HSR line is just a railway line built to higher standards:

- larger curve radiuses (spelling?). Not much of a factor when a line mostly crosses sparsely populated, flat areas.

- less steep inclines (but if a steam engine can climb an incline, so should every modern train)

- Switches that allow high speeds on the diverging branch. But again, if the population is sparse, you don't need many of them.

And when building a part of the line to HSR standards is too expensive, the HSR train just turns into a regular train while using it. The only part that's expensive even if the geography is great is electrification (having to carry fuel or batteries limits your speed).

Switzerland does not use HSR despite prioritizing rail. I couldn't find numbers, but AFAIK it's very densely populated if you exclude the uninhabitable parts of the alps. Germany is slightly less densely populated and does use HSR. France has less than half the density and its HSR is significantly faster than Germany's. It does not look like HSR requires a high population density. The opposite is the case: HSR works better when it can go long distances without stopping and re-accelerating.

And even if HSR does not make sense everywhere, that is not a reason not to use it where it does.

[fanf2]

High speed lines can have steeper profiles than normal lines because the greater kinetic energy and loco power makes them less troubled by slopes. Eg this compares the profiles of the old Paris-Lyon route with LGV Sud-Est:

http://www.railfaneurope.net/tgv/images/misc/profilln1.jpg

[anoncake]

Even better. Though this particular example compares the difference between a general-purpose railway line designed for steam traction and a passenger line for electric ones.