[throwaways85989]

Train boarding at least could be decoupled from slowing down and stopping. Just have a "Shuttle Wagon" depart pre arrival from the train with those who want to get out and another one speeding up with new passengers after the train as it passes through the station. Under ideal circumstances, a train would actually not even have to slow down for this. Con is that there is always a Shuttle in the station.

[rhodorhoades]

But then you might as well go for the ‘Teslas in tunnels’ approach like the boring company.