[VLM]

I wouldn't worry about an air valve being left open quite as much as the vacuum being broken because a big chunk of concrete (or whatever) is now sucked into the tube in the path of the train.

Perhaps in the very unlikely event it ever rains again in California, water in the tube could be an issue, or lightning damage. That brings up the logical question of how many customers you'll have if none of them have any water to drink. Perhaps this would make more sense as a project under the Chicago Regional Transit Authority, or parallel to the existing Acela track on the coast.

[danielweber]

> because a big chunk of concrete (or whatever) is now sucked into the tube in the path of the train

1 atmosphere of pressure isn't going to suck in anything concrete, except maybe in dust format.

[eclipxe]

Yeah because CA is going to depopulate because of the drought. Come on be realistic.