Rumor: High-speed tube travel concept in the works

[kentauros]

74. You're still going to have hilly grade to navigate.

Someone here mentioned that you won't have turns, you'll have bends, and those based on at least 100-mile radii. Hills are here and gone often in less than one mile before the next one starts. You can't build at grade in that kind of terrain if you can't make hilly bends. Roads and (low-speed) rail don't have such restrictions. So, it would likely have to be drilled its entire length due to this major problem.

As I recall from all those science fiction stories from many decades ago, every single one of them had done this very thing: drilled the entire length to ensure extremely shallow curves and to avoid mountain ranges and other above ground obstacles. You're going to have to avoid cities, too, other than starting and ending, so you drill under them as well.

There are relatively few areas of the entire continent that would be flat enough to have this above ground. Everything else has "wrinkles" and would not be conducive to building this at grade.

http://en.wikipedia.org/wiki/File:North_america_terrain_2003_map.jpg