Cambridge City Center has a designated "Pedestrian Zone" in operation 24/7 where general vehicle access is limited and controlled by bollards. This is further heightened between the hours of 10 a.m. and 4 p.m. Monday through Saturday. Typically, only buses, bicycles, and some authorized vehicles are allowed within this zone. A park-and-ride service allows visitors to park at one of 5 free parking lots on the outskirts of the city and take the bus to central destinations.