What: Submerged OCEANIC tunnel and supersonic train
WHERE: New York London
Cost: $88 billion $175 billion
Crux: Neutrally buoyant vacuum tunnel submerged 150 to 300 feet beneath the Atlantic's surface and anchored to the seafloor, through which zips a magnetically levitated train at up to 4,000 mph.The idea is as wondrous as it is audacious: Get on a train at New York City's Penn Station and hit Paris, London or Brussels just an hour later. "From an engineering point of view there are no serious stumbling blocks," says Ernst Frankel, retired professor of ocean engineering at MIT.