Suhi Boat

I took this photo at the Sushi Boat restaurant in Newtown earlier this year. I snapped this one photo before they told me to stop.

I was confused as to what made the boats go around? A current? Magnets? I tried to stop the boats but they had some force behind them.
I went back to this place a month ago and it had changed to a Sushi Train?!
Why is most sushi served on trains?

The place had one original thing going for it, a boat not a train serves the food, and then it gets bought out by the Sushi Train people.

Do they have Sushi trains in the USA and UK? Or is it just an Australian thing?