Re: Aircraft/public Transit
Trains are most practical for shorter distances where air travel isn't worth the short hop. Only problem is that the places where this would be most useful (say the Atlantic coast) are already heavily built up (thus William Gibson pictured the entire east coast becoming one huge megapolis called the Boston-Atlanta Metropolitan Axis or BAMA, better known as The Sprawl). Trying to build new infrastructure in a place that's already heavily built up is going to be expensive and time-consuming (= unpopular with the taxpayers). For a prime example, consider Boston's "Big Dig" project.