Subway The Toronto subway system consists of the Line 1 Yonge–University, a U-shaped mostly north–south line that was opened in 1954 and was last extended in 2017; Line 2 Bloor–Danforth, an east–west line that was opened in 1966 and was last extended in 1980; Line 3 Scarborough, a partly elevated light metro line that was opened in 1985 and continues from Line 2 Bloor–Danforth's eastern terminus; and Line 4 Sheppard, which was opened in 2002. The three subway lines are served by 678 cars grouped in trains of four cars on Line 4 Sheppard subway, and six cars on Line 1 Yonge–University and Line 2 Bloor–Danforth. The three subway lines share non-revenue track connections and use the same technology. The train versions in use consist of the Toronto Rockets on Lines 1 and 4 and the T1s on Line 2. Line 3 Scarborough has a fleet of 28 S-series cars grouped into trains of four cars each and is not compatible with other subway lines, given that the S-series cars use . It shares no track connections or equipment. Due to the increasing difficulty of performing critical maintenance work on the S-series trains, the existing Line 3 Scarborough service is expected to be decommissioned and demolished permanently in 2023. It will be replaced by TTC bus service until the Line 2 Scarborough subway extension to Sheppard and McCowan opens for revenue service in 2030 at the earliest. All subway lines provide service seven days a week from approximately 5:45 a.m. to 1:30 a.m. (the following day) (last train runs at approximately 1:45 in each direction) except for Sundays, in which the opening is delayed until approximately 8:00 a.m. During the overnight periods, the subway and its stations are closed to perform maintenance at track level and in the stations themselves. Overnight service is provided by buses and streetcars operating above ground. These overnight routes are issued numbers in the 300 series and are referred to as Blue Night routes, indicated by a typical TTC bus stop sign with a blue band added. Projects under construction Line 5 Eglinton, which uses light rail vehicles, is under construction and is expected to open later in 2023. It will run underground in the central part of the line from west of Keele Street to Laird Drive, with most of the remainder of the route travelling at grade, though Science Centre station will be