The IET’s Engineering and Technology magazine this month has an article about a proposed light rail system called Nowait in Sweden. The track forms a loop and so does the train. In the station carriages turn sideways and go slowly enough to let people on, then they turn lengthways and speed up to 40km/h. There are a couple of animations on the company’s site if you click the “how it works” link.
It looks cool, but I have reservations. All the carriages are linked together, so if there is a problem the whole system would need to be stopped, leaving people stranded between stations. The system can’t adapt to busy and quiet periods. And I wonder how long you will have to wait to pass through each station. But if it gets built I will go and try it out.