Transport approved the building of the tunnel and a third underground four-track Löwenstrasse station. In September 2007, construction began on the project, nicknamed "Durchmesserlinie" (cross-city link). On 14 June 2014, the new platforms and tunnels were opened. The new line runs from the Altstetten railway station, crosses the Zürich HB station throat on a bridge, and leads into the underground Löwenstrasse station. From there, it goes through the new, approximately long Weinberg Tunnel in a long left-hand curve under the existing Zürich HB–Stadelhofen line. It then ends at the level of the portals of the existing Wipkinger Tunnels in Oerlikon, where it connects with the northbound lines, including the line to Zürich Airport and Winterthur. In 2007, the SBB and Deutsche Bahn entered into a station partnership between the Zürich HB and the Berlin Hauptbahnhof to promote knowledge sharing between operators of similarly sized stations. Layout and facilities Layout The station is aligned approximately east to west, at the northern edge of the city centre and the northern end of Bahnhofstrasse, the city's main shopping street. It is split over three principal levels, with the ground level housing sixteen terminal platform tracks and the station's main concourse. Below this level are a series of pedestrian passageways, the ShopVille shopping centre, and the course of the Sihl river. At the lowest level, and parallel to the terminal platforms at ground level, are ten underground platform tracks, of which two are terminal and eight are through. The station's main concourse itself comprises two sections. To the east is the Haupthalle (Main Hall), which was the train hall of the 1871 station but is now a pedestrian circulation space. The Haupthalle is surrounded on three sides by station buildings, whilst to the west it opens onto the Querhalle (Cross Hall), which stretches across the head of the ground level terminal platforms. These platforms, comprising two side platforms and seven island platforms, are sheltered by the 1933-built train shed and are served by tracks numbered 3 to 18. At the middle level, the station site is crossed north to south by four pedestrian passageways. The eastern three of these, the Passage Bahnhofstrasse, the Passage Löwenstrasse and the Passage Gessnerallee, form an interconnected complex with the ShopVille shopping complex and give direct access to all the station's platforms as well as to the surrounding streets. An intermediate underground level, immediately below the Haupthalle, connects these