I feel that when the total cost of rail is taken into account, there are only a few very high density areas or high traffic routes where they make sense. I was recently reading about how large stretches of China's bullet train system cost tens of billions of dollars, and ongoing expenditure of billions more, and have hardly enough traffic to justify their maintenance, let alone their construction costs. There are some routes that are well utilized, but it seems that when you empower the government to make such infrastructure, there is massive malinvestment ... and its hard to know what the alternative could have been without such centralized planning.