High Speed 1 (HS1), legally the Channel Tunnel Rail Link (CTRL), is a 67-mile (108 km) high-speed railway linking London with the Channel Tunnel. The line carries international passenger traffic between the United Kingdom and mainland Europe; it also carries domestic passenger traffic to and from stations in Kent and east London, and Berne gauge freight traffic. From the Channel Tunnel, the line crosses the River Medway, and tunnels under the River Thames, terminating at London St Pancras International station on the north side of central London. It cost £5.8 billion to build and opened on 14 November 2007. Trains run at speeds of up to 300 kilometres per hour (186 mph) on HS1. Intermediate stations are at Stratford International in London, Ebbsfleet International in northern Kent and Ashf