By the time the coast-to-coast train is built it will not be good enough. There will be a call for the replacement. Perhaps one that is a vacuum tube with the air removed to reduce air resistance and Maglev with linear induction motors to eliminate mechanical resistance. Hyperloop at 800 mph! Before that technology is perfected, no coast-to-coast trains, please!
https://www.youtube.com/watch?v=zcikLQZI5wQ