High Speed 1

High Speed 1 (HS1), officially the Channel Tunnel Rail Link (CTRL), is a 109.9-kilometre (68.3-mile) high-speed railway linking London with the Channel Tunnel.

It is part of the line carrying 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 continental European loading 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 £6.84 billion to build and opened on 14 November 2007. Trains run at speeds of up to 300 km/h (190 mph) on HS1. There are intermediate stations at Stratford International in London, Ebbsfleet International in northern Kent and Ashford International in southern Kent.

International passenger services are provided by Eurostar International, with journey times from London St Pancras International to Paris Gare du Nord in 2 hours 15 minutes, and London St Pancras International to Brussels South/Bruxelles-Midi/Brussel Zuid in 1 hour 51 minutes. As of November 2015, Eurostar uses a fleet of 27 Class 373/1 multi-system trains capable of 300 km/h (190 mph) and 320 km/h (200 mph) Class 374 trains. Domestic high-speed commuter services serving intermediate stations and beyond began on 13 December 2009. The fleet of 29 Class 395 passenger trains reach speeds of 225 km/h (140 mph). DB Cargo UK run freight services on High Speed 1 using adapted Class 92 locomotives, enabling flat wagons carrying continental-size swap body containers to reach London for the first time.

The CTRL project saw new bridges and tunnels built, with a combined length nearly as long as the Channel Tunnel itself, and significant archaeological research undertaken. In 2002, the CTRL project was awarded the Major Project Award at the British Construction Industry Awards.

The high-speed railway operates as a "seven-day railway", with full availability on all days. Heavy maintenance is performed overnight. As of 2008^[update], track access charges were capped at approximately £71.35 per minute. In 2008, the cost of running a train along the full length of the line between St Pancras and the Channel Tunnel was £2,244; with lower costs of £2,192 for a domestic service to Ashford International, or £1,044 for St Pancras to Ebbsfleet International. A discounted rate of £4.00 per kilometre was made available for night-time-only railfreight operation until 31 March 2015.

Section 1 of the Channel Tunnel Rail Link, opened on 28 September 2003, is a 74 km (46-mile) section of high-speed track from the Channel Tunnel to Fawkham Junction in north Kent with a maximum speed of 300 km/h (190 mph). Its completion cut the London–Paris journey time by around 21 minutes, to 2 hours 35 minutes. The line includes the Medway Viaduct, a 1.2 km (0.75-mile) bridge over the River Medway, and the North Downs Tunnel, a 3.2 km (2.0-mile) long, 12 m (39-foot) diameter tunnel. In safety testing on the section prior to opening, a new UK rail speed record of 334.7 km/h (208 mph) was set. Much of the new line runs alongside the M2 and M20 motorways through Kent. After its completion, Eurostar trains continued to use suburban lines to enter London, arriving at Waterloo International.

Unlike most LGV stations in France, the through tracks for Ashford International station are off to one side rather than going through, partly because the station pre-dates the line. High Speed 1 approaches Ashford International from the north in a cut-and-cover "box"; the southbound line rises out of this cutting and crosses over the main tracks to enter the station. The main tracks then rise out of the cutting and over a flyover. On leaving Ashford, southbound Eurostars return to the high-speed line by travelling under this flyover and joining from the outside. The international platforms at Ashford are supplied with both overhead 25 kV AC and third-rail 750 V DC power, avoiding the need to switch power supplies. Within Ashford, the speed limit on High Speed 1 is 270 km/h (170 mph).

Section 2 of the project opened on 14 November 2007, and is a 39.4-kilometre (24.5-mile) stretch of track from the newly built Ebbsfleet station in Kent to London St Pancras. Completion of the section cut journey times by a further 20 minutes (London–Paris in 2 hours 15 minutes; London–Brussels in 1 hour 51 minutes). The route starts with a 3.1-kilometre (1.9-mile) tunnel which dives under the Thames on the edge of Swanscombe, then runs alongside the London, Tilbury and Southend line as far as Dagenham, where it enters two long tunnels to reach St Pancras. The two tunnels (much of which is directly under the North London Line) are 10.1-kilometre (6.3-mile) and the 7.5-kilometre (4.7-mile) in length, split by a 1-kilometre (0.62-mile) stretch that runs close to the surface to serve Stratford International and the Temple Mills Depot. The new depot, to the north of Stratford, replaced the North Pole depot in the west of London. In testing, the first Eurostar train ran into St Pancras on 6 March 2007. All CTRL connections are fully grade-separated.