The HSL 4 (Dutch: Hogesnelheidslijn 4, English: High-Speed Line 4) is a Belgian high-speed rail line part of the 87 km axis which connects Brussels to the Dutch border. 40 km long (36 kilometer of it dedicated high speed tracks), it was scheduled for completion by 2005 and opened in 2009.
Together with the HSL 1 to the French border and HSL-Zuid to Amsterdam, the line has shortened journeys between Brussels, Paris and the Netherlands. HSL 4 is used by Thalys trains and fast internal InterCity trains (Class 13 locomotives with I11 vehicles). It is also planned to be used by Fyra and, tentatively, Eurostar e320 and DB Baureihe 407 trains.
Read more about HSL 4: Route, Stations, 'Solar Tunnel'