Actually there have been plans for an underwater maglev train that could cross.oceans. The Trains are in vacuum steel and concrete tubes that are buoyant they are suspended from the sea floor on anchors like oil rigs use on tension leg platforms. the tube would be 100 to 200 feet underwater the whole way. this puts the tube out of any conceivable storm wave base and below the deepest keel of shipping. being buoyant and in constant tension to the seafloor means the tubes cannot drift laterally or in depth they are fixed with the exception of cable stretch but just as with rigs the cables can be pre tensioned to remove any slack from strain.
There are already underwater tunnels with similar engineering that cross.fjords in Norway but with cars and rails. at 200 feet subsea even pulling a hard vacuum in the tubes only adds 14.5 psi to the structural loads its miniscule compared to what prestresses concrete can take in compression think 15000 psi.
the reason for the vacuum is maglevs have no limit on speed one can make the propulsion magnetic.wave as fast as electronics can be switched as in nanoseconds. in a vacuum a maglev could exceed.mach 5 without any air resistance or frictional heating it would be a hyperloop on steroids the technology all exists today. cost estimates run into the high hundreds of.billions but it could be done from an engineering stand point. this is how you cross an ocean with out flying. I believe the show extreme engineering did an episode on this concept a few yesrs back.
Imagine what a rogue nation with submarines could do to that system.
That is, after all the fossil fuel-powered airliners are scrapped and airports are reconfigured as sites for free low-income housing.
Actually there have been plans for an underwater maglev train that could cross.oceans.
thanks didn’t know that. Wonder how they would be supported even that far down, and how those would be constructed when the depths are in the thousands of feet