Just a hunch, I suppose!
It should seem obvious to even the casual observer. You just have to make a grade and lay some track for a high speed rail (concrete and/or asphalt for a highway). An evacuated transatlantic tunnel costing LESS?!?! C'mon.
It should just be common sense. No issues about pressure, weather, ocean currents, new technology, etc., with a high speed rail or highway.
I'd be nervous riding in a vacuum tunnel across the ocean. One little leak and you're in trouble. The safety standard would be so much higher compared to any issues regarding rail or highways that it would dramatically increase costs. That's not to mention the massive equipment needed to keep the tunnel in an evacuated state.
Even not accounting for the cost of developing the new technology, even if you just compare cost of construction, there's no way you'll ever convince me that such a project could be accomplished for less per mile than laying track or highways, let alone one quarter to one tenth the cost.
These sound like short sighted numbers cooked up by someone with a stake in the project. As I said, common sense would suggest otherwise.
