[Porsche-O-Phile]

It would be far cheaper to develop a viable HST (hypersonic transport) and then either fly it offshore to avoid the sonic booms annoying the big-money residents of Santa Barbara or Malibu or designing it such that the shock waves primarily propigate upwards (this is already being worked on). Then there's no land-based infrastructure other than runways/airports (which exist already), no easement issues and it can fly anywhere, not just on the leg SFO->LAX. It's also a lot less terror-proof (harder to blow up something at high altitude over the ocean than with miles of tube/supports running through the middle of nowhere).

You would still have to deal with the TSA morons to fly on it though, so maybe that'd kill it and make it unviable. I doubt many people would pay $2k-$3k to get their junk grabbed by Heavy Helga the Transsexual TSA Agent.