The tram system is currently undergoing major expansion with 4 new lines under construction by 2016, and further potential extensions to Stockport and the Trafford Centre envisaged, with a Manchester City Centre "crossing" line planned to ease congestion. Work on the new lines started in late 2008 which will extend the system to East Didsbury, Ashton-under-Lyne, Oldham, Rochdale, MediaCityUK and Manchester Airport.