HSL 3
The HSL 3 (, , ) is a Belgian high-speed rail line. It connects Liège to the German border near Aachen. The high-speed track length is . The line was technically completed in October 2007; however, it did not come into operation until 14 June 2009, when ICE trains began service. Thalys trains have been using the line since 13 December 2009. The interval between completion of the line and its actual use was due to difficulties in the implementation of the safety system ETCS level 2, specifically, finding trains with ERTMS fitted. Together with the HSL 2 and HSL  1 to the French border, the combined eastward high-speed line has greatly reduced journey times between Brussels, Paris and Germany. HSL 3 has cut Liège – Cologne journey times from 1 h 23 min to 1 h 1 min. HSL 3 is used only by international Thalys and ICE trains, as opposed to HSL 2, which is also used for fast internal InterCity services. Route. Trains leave the reconstructed Liège-Guillemins station over the upgraded "classic" line, at speeds which progressively rise to . The dedicated high-speed tracks branch off from the "slow" line at the bridge over the Ourthe , between Angleur and Chênée stations in the suburbs of Liège. The line crosses the Vesdre river, then traverses the long Soumagne Tunnel between and Soumagne. This is the longest double-track tunnel in Belgium, and has a speed limit of . The line then runs parallel to the A3 motorway with a speed limit of shortly after the village of Walhorn, it passes under the A3 in a cut-and-cover section, and rejoins the regular line. Trains run on the upgraded classic line 37 at , pass over the Hammerbrücke viaduct (entirely reconstructed for the project), and cross the border further  on. Beyond the border, high-speed trains travel along upgraded existing rail lines to Aachen Hauptbahnhof. Trains use left-hand running along this section (as in Belgium), switching over to right-hand running, which is common in Germany, at Aachen Hauptbahnhof. Construction. Infrabel, the Belgian rail infrastructure manager, constructed the line through its subsidiary TUC Rail, who built the line between 2001 and 2007 at a cost of €830m, including ETCS Level 2 signalling. The most notable construction subproject is the long tunnel at Soumagne, which is the longest railway tunnel in Belgium. The bored section is , extended  by covered sections of respectively and . Dozens of geological layers of differing hardness had to be tunnelled through, lime layers needing to be blasted through with dynamite. The tunnel reaches a depth of in some areas; it has an average ramp height of 1.7%, with a maximum of 2% at the entrance in Soumagne. The free space profile in the tunnel is approximately , which restricts speeds to . The tunnel was built between 14 May 2001 and August 2005.