Dee and the rest of the Bayesian Nakama are financing and building a new colony on the asteroid (442) Eichsfeldia. While said asteroid is 66 km across, its surface gravity is only 0.2% that of Earth's - pretty much freefall. In order to attract long-term settlers, the Nakama had to provide some way for them to avoid the negative biological effects of living for years on end without gravity.
Their solution: they dug a tunnel in a great big circle, about three miles long and a mile in diameter; installed a mag-lev train track on the 'outside' of the circle; and started building train-cars for it, running them around and around at around 200 mph, or taking about a minute to travel the whole route. Due to the magic of centrifugal force, anyone inside such a traincar feels a force equivalent to Earth's gravity.
There's room for about 400 standard 40-foot cars on that track, providing room for about 1600 colonists. There's also additional a second line of track on which run a bunch of half-sized "elevator" commuter cars, a swimming-pool car, a medical car, and similar accessories. Each colonist has as much cavern space as they want, for whatever possessions they have and activities they enjoy which don't require gravity (or a reasonable facsimile thereof). The whole collection of train, tunnels, shipyard, refineries, factories, and so forth, now forms the town of Oakfield.
During normal operations, the train never stops. To board, residents board the commuter cars, which speed up to match the residential train, match up with the right car, and connect hatch-to-hatch, side-by-side; leaving is the same thing in reverse. In emergencies, the train can stop, and individual cars can shift onto the commuter siding, such as for maintenance or upgrades.
During normal operations, the train never stops. To board, residents board the commuter cars, which
