[samatman]

I've mused about a similar idea for California's high speed rail, which, should it ever be built, would be rendered impractically slow by frequent stops.

The idea is to drop cars without slowing down. These cars would have brakes, that's it. Before the station, drop the car, it slows enough to give safe time for switching, and cruises to a halt at the local station.

That's drop off, pickup is the slow train, which runs twice a day in each direction and assembles the carriage on the way.

Impractical for various reasons, sure. But what if.

[not2b]

The plan for California high speed rail was to replace plane flights and long distance car travel, not to have frequent stops (at least 40 miles/65 km between stops, sometimes longer). Only the major cities.

[samatman]

Yes, that was the plan. The raison d'être, even. But if it ever gets built, it will be obliged for political reasons to stop so often as to make it an unattractive alternative to flying from SF to LA or vice versa.