 Perth provides zero-fare train trips for SmartRider (travel fare card) holders around the city centre (the "Free Transit Zone"), as well as four high-frequency (every 8–15 minutes) Central Area Transit (CAT) bus routes (Red, Blue, Yellow, Green), which, alongside trips on regular Transperth buses in the city centre, are free to all users.There are five main rail lines, 70 stations and 15 bus stations in the metropolitan area.An extensive bus network services the greater Perth metro area.