OC Transpo's O-Train is a multimodal light metro system consisting of two lines: the east–west Confederation Line (Line 1), a 12.5 kilometre metro system operating medium capacity electric trains along a partially underground route that cuts through the downtown; and the north–south diesel-powered Trillium Line (Line 2), originally an 8-kilometre system from 2001 to 2020, which will be expanded to 19 kilometres upon the scheduled reopening in September 2022. The Airport Link (Line 4), a 4-kilometre system sharing track with the Trillium Line but operating as a distinct segment, is also scheduled to open in September 2022.