Docking wouldn't have to occur at high speed, or moving at all, for this to be useful. For example, I live in Massachusetts and I have a car full of gear that I

Docking wouldn't have to occur at high speed, or moving at all, for this to be useful. For example, I live in Massachusetts and I have a car full of gear that I'd like to have for my vacation in New Hampshire or New Jersey or Michigan. So I drive down to the local train depot, where my car is docked (or even just loaded onto) a train, I get in the passenger compartment, we're reunited at the other end. Already more efficient than driving, and more pleasant too. Now start adding tweaks like loading only the passenger compartment, which is already a separate thing in electric vehicles. Or running rails along one lane of existing highway, with docking/undocking at existing rest areas. Once the basic "dock instead of driving" idea gets established, it's possible to iterate on it.