trainman74
Engineer
Pittsburgh's light rail system, the "T," has a free fare zone. It's not terribly easy to find on the ill-designed website, but a little more transparent once you descend into the station.
Interesting that they phrase it as "pay where you live" on the website, since there are probably some people who live within the free fare zone.
Buses also used to be part of that same free fare zone, because the same fare payment method was used (pay when you enter inbound, pay when you exit outbound), but now buses are pay when you enter at all times.