Currently, with the exception of the Red Line and the Blue Line, all lines operate at all times except late nights. Prior to 1998, the Green Line, the Purple Line and the Douglas branch of the Blue Line also had 24 hour service. In the years of private ownership, the South Side Elevated Railroad (now the South Side Elevated portion of the Green Line) provided 24 hour service, a major advantage when compared to Chicago's cable railroads which required daily overnight shutdown for cable maintenance.