Public transit seems to share many of the characteristics of the third place, as Ray Oldenburg calls them in The Great, Good Place. They're full of people from all walks of life, having random conversations, and brings several of the same people together with amazing regularity.
Sitting at a cafÃ© as I write this, and having used public transit for the three months of my internship at Google, I've wanted to pen these thoughts down for a long time. Every morning and every evening, I used to hang out with the same set of people. Sometimes a few fresh faces would make their way onto the bus; sometimes one of the regulars would sleep in late and miss their bus.
Whenever I happened to take a later bus than usual, some time around noon, the commuter crowd would have shrunk down to a trickle, and most passengers would be headed to finish off errands, or simply out and about the Bay Area. These passengers had an even greater rapport with the bus driver: I've been part of thoroughly engaging conversations with these people, who I do not know the names of, and probably never will. For them, it was a natural group that had formed because of their respective travel habits.
Public transit is markedly absent in America, but it is alive and kicking in most other countries: I've seen it in Dublin, I've seen it in MontrÃ©al, I've seen it in Bombay. The local trains of Bombay are the lifeline of the working population. The frequency and timeliness of the trains is something to be proud of (regrettably, the same cannot be said of the rest of the population.) Thus, groups of commuters who travel by the same trains day in and day out form their own cliques. There's even a name in the local lingo for it: "train friends." Just as you have family friends and work colleagues, this is a part of your social life that stays with you for a significant part of your life. You don't visit the homes of your train friends; you hardly talk shop with them; and you hardly meet them outside of the commuter context. But the place is a third place, after all.
As in all the other instances of the third place having a strong existence in Europe and all over the world, but lacking in America, the "place" of public transit exhibits similar properties. In USA, commuters are holed up in their oil-fueled cars and vans and SUVs, all the while blaming the other guy for causing all the traffic jams on the 8-lane highways. It is obvious that this causes at least a small amount of increase in stress levels of the driver (though I can't be bothered to look up a citation for that right now.) Compare that to urban populations elsewhere that share conversations on a bus or a train.
Ray Oldenburg could probably add "keeping stress levels low" to the ways in which third places affect the daily lives of those who inhabit them.