UK spent $100M just to deal with bats in a single train tunnel, which is representative of the issue https://www.bbc.com/news/articles/c9wryxyljglo
China just doesn't have to worry about environmentalists or anyone else locally trying to stand in the way, they just bulldoze them and build.
China also has much lower labor costs, and even Japan is a good bit cheaper (than the US, at the least)
The metro area density of Tokyo is 3,000 / km^2
The metro area density of Beijing is 1,747 / km^2
Greater Los Angeles: 208 / km^2
A perhaps more interesting use case is the utsunomiya light rail. Utsunomiya has a density of around 1200/km^2.
What they ended up doing was building a new tram with exactly one line. The main thing they did was make sure the tram comes frequently, including off peak.
End result is people rely on the tram line and the tram is making good money, being operationally profitable (still gotta pay back construction costs of course).
Utsunomiya is obviously not exactly greater LA, but Utsunomiya has on average 2.25 cars per household[0]. It has traffic issues and people feel the need to own a car. And yet the tram line is finding success because transportation is a local issue, not a global one!
You can solve for transportation issues in crowded areas. Few reasonable people are lamenting that you don't have a train between madison, WI and Chicago every 15 minutes. Many are simply lamenting that even at a local level PT in many places is leaving a lot on the table despite there being chances of success!
Smaller focused PT has proven itself to work time and time again, and compounds on other PT projects in the area.
[0]: https://www.pref.tochigi.lg.jp/english/intro/overview.html
Most of the rail has get around mountainous, uneven terrain subject to earthquakes, strong winds, and heavy rain. California should be able to build rail parallel to the I-5, a long, flat terrain without extreme weather or strong earthquakes. The problem seems to be a political one, not an engineering one. In fact, if the Interstate Highway System did not already exist, I doubt the U.S. today would be able to accept and complete it.
> one long line with a few branches
I currently live in Japan, and that does not really match what I've observed. There are three distinct railway companies in my area (JR, Tokyu, Yokohama Municipal Subway), each with their own dedicated rail, trains, power supply, etc.
The situation is more like "a disjoint union of graphs, where some of the graphs are connected".
https://www.metro.net/about/media-relations/156-million-new-...
It has to be said: even in Japan train projects are multi decade projects.
Is Cali HSR stopped? I can imagine it being slow but I wonder if it's 10x slower or "merely" 3x slower.