Bhopal and Itarsi & Budhni has been completed till April 2020. Dual gauge The Melbourne to Albury railway originally consisted of separate gauge and gauge single track lines, but when traffic on the broad gauge declined, the lines were converted to bi-directional double track gauge lines. Quadruple track Quadruple track consists of four parallel tracks. On a quad-track line, faster trains can overtake slower ones. Quadruple track is mostly used when there are "local" trains that stop often (or slow freight trains), and also faster inter-city or high-speed "express" trains. It can also be used in commuter rail or rapid transit. The layout can vary, often with the two outer tracks carrying the local trains that stop at every station so one side of stations can be reached without staircase; this can also be reversed, with express trains on the outside and locals on the inside, for example if staffed ticket booths are wanted, allowing one person for both directions. At other places two tracks on one half of the railway carry local trains and the other half faster trains. At the local train stations, the express trains can pass through the station at full speed. For example on the Nuremberg-Bamberg railway, which is quadruple track for most of its course, the inner two tracks are used by the S-Bahn Nuremberg whereas the outer tracks are used for regional express and Intercity Express trains. The section in northern Fürth where the line is "only" double track creates a major bottleneck. For Berlin Stadtbahn the two northern tracks are local S-Bahn and the two other for faster trains. The most notable example of quadruple track in the United States, and perhaps the only four-track section of mainline therein, was the Pennsylvania Railroad's main corridor through the heart of Pennsylvania around the famous Horseshoe Curve. This line is now owned by Norfolk Southern. Other examples include the Hudson and New Haven Lines, both of which are shared between Metro-North and Amtrak in New York and Connecticut. The New Haven Line is quadruple track along its entire length, while the Hudson Line is only quadruple tracked along the shared portion from Riverdale to Croton–Harmon and along the shared track from Grand Central Terminal to Yankees–East 153rd Street. Amtrak's Northeast Corridor is quadruple tracked in most portions south of New Haven, but also has a few triple-track segments. The Metra Electric District is quadruple-tracked