Melbourne has a great public transportation system - with a network of trams. In the central city zone riding is free. You use Myki cards to pay by swiping when you get on and get off. Most of the trams are articlated cars with 3 or 4 doors - each door is wide enough for two people with a machine on each side of the door so 6 or 8 people could be entering at once. The traffic signalling system gives the trams priority.
This is a lot better than the Boston MBTA with lines of people using Charlie cards (quick), Charlie tickets (slow), and cash (slower) with only one machine. The trams were all pretty modern with audible announcements and displays. There is a free circle route that goes around the edge of the free zone.
A PDF of the tram map is here:
Click for these pictures: