There is a bus in Philadelphia which SEPTA does not talk about. It is not listed on the website. It has neither schedule nor route. It drives the city in a pattern known only to its driver, and perhaps not even to him. Its electronic reader board never displays a number, only “SEPTA.” People who know it call it the Zero, the Random Bus, the Wandering Bus, or just The Bus. It is not a bus for people who know where they want to go. It is a bus for departures.