We were allowed a round trip, once, when it was pouring rain and no one was getting on or off the vehicles. LOL We were on the double decker bus, the top was flooded and closed and we talked to the driver of the bus for a few rides up and down MS, it really was great. But we were the only people on the bus so it was all good, once we saw people starting to wait we hopped off at the next stop. But yes, generally it's a 1 way ticket, no charge and you just find the signs and wait. They do stop the vehicles sometime after noon, I don't know when exactly tho.