Transport 21 was an Irish infrastructure plan, announced in November 2005. Its aims were to greatly expand Ireland's transport network. A cost estimate of €34 billion was attached to the plan at the time. The plan included continuing investment in Ireland's road network, along with investment in public transport in the form of buses and rail. After the collapse of the Irish banking system the Transport 21 project was cancelled in May 2011. A significant portion of this investment would focus on the creation of an integrated rail network in Dublin. Projects included a tunnel under Dublin city centre connecting Heuston Station with Pearse Station and Docklands station at Spencer Dock. This would facilitate the expansion of the Dublin Area Rapid Transit (DART) system from one line to two. Also included were several new Luas lines, a metro system, and tighter integration between all rail systems, particularly at the planned St. Stephen's Green interchange. This would create a single integrated rail network in Dublin that served the north, south, east and west of the city. Other rail investment included the planned Western Railway Corridor, redevelopment of a rail link from Navan to Dublin and upgrading and extending suburban rail in Cork. Also included in the plan was the significant expansion of the Dublin Bus passenger-carrying capacity, completion of the motorway system linking all the major urban centres on the island, and better integration of all transport systems. Luas - Dublin St. Stephen's Green to Luas Red Line (Line BX) The RPA (Railway Procurement Agency) announced the new preferred route extension from the Green Line stop at St. Stephen's Green to Luas Red Line (Line BX) in 2011. The route continues on from St. Stephen's Green towards Dawson Street, Grafton Street Lower, College Green, Westmoreland Street, O'Connell Street and Parnell Square. Construction of the line began in June 2013 and was opened on 9 December 2017. Connolly to Point Depot (Line C1) The route for the Red Line extension (Line C1) from Connolly to the Point Depot was fixed in the early 2000s and the Railway Order was signed by the Minister of Transport in December 2006. Construction works got underway in June 2007, with the centrepiece being a new bridge at the Harbourmaster Place end of Mayor Street. It was officially opened in 2009. Sandyford to Brides Glen (Line B1) The route for the Green Line extension (Line B1) from