A large part of what made the shinkansen work in ways that the current US rail system doesn't is its dedicated right of way, so I think building it separately m

A large part of what made the shinkansen work in ways that the current US rail system doesn't is its dedicated right of way, so I think building it separately makes some sense. sharing with freight otrain slower commuter trains really reduces the value of HSR, especially on an older, slower right of way.