At Central Station's opening, tracks (7, 8, 9, 10, 11 and 12) of the Tunnel Station were used only by trains heading north through the tunnel, and they did not continue south of the station. These tracks were finally connected to the south when the old Tunnel Station was demolished as well as the warehouse located south of De la Gauchetière Street and east of Inspector Street (now Mansfield Street). This also allowed for the construction of the new headquarters of CNR as well as Place Bonaventure. This division is once again in effect following the rebuilding of the Deux-Montagnes line. These tracks are now part of the Two Mountains Subdivision, extending south for a distance of about 1600 metres. Under catenary wires, they serve as parking for trains on the Deux-Montagnes line during the day. Since the reopening of the Mont-Saint-Hilaire line, they are also used to park trains from this line.