They do sound fun.
It is point to point travel.
Imagine that the bus/train only had enough seats for you and one friend ( but there were many buses) and always one waiting for you at a station for when you wanted to travel.
If it was based on going fast they should be able to hit somewhere near 100km per hour.
But as I said, several have built them, and they always tend to be large cluncky cars on a rail.
I wanna ride a rollercoaster to work (smooth with no loops or similar)

Ill see if I can find a link