Plans have been announced to double the train tracks between Connolly and Malahide and stations. The major infrastructure project is aimed at relieving pressure on Ireland's busiest rail line. As part of the Four North project the 14 kilometer, two-track line will double to four tracks. Some gardens and other private property along the line will be needed for construction as part of the plans, which are estimated to cost more than a billion euro. The project will allow for a faster Dublin to Belfast Enterprise service, expanded DART services and improved northern line commuter services.