Roughly 171,000 workers in the city of Philadelphia use public transportation, the fourth largest number of any U.S. city (note: that figure does not include those who travel from outside the city into Philadelphia). The system combines underground subways, street-level trolleys, trolley buses, regular buses and commuter rails. The various types of trains account for more than 290,000 rides on a typical weekday, while buses and trolley buses move about 490,000.