High Speed 2 (HS2) is a planned high-speed railway system in the United Kingdom, with its 176 kilometres first phase under construction and future stages awaiting approval. HS2 will be the second major high-speed rail line in Britain; the first is 108 kilometres High Speed 1 (HS1), which connects London to the Channel Tunnel and was opened in the mid-2000s. Upon completion, with a new "Y"-shaped network of track and a design speed of , the new railway will link London, Birmingham, Manchester and Leeds.