Line containing four paths for trains
A quadruple-track railway (also known as a four-track railway) is a railway line consisting of four parallel tracks with two tracks used in each direction. Quadruple-track railways can handle large amounts of traffic, and so are used on very busy routes or sections. Such conversion is referred to as "quadruplication".
A railway line with six parallel tracks, or a sextuple-track railway, has three tracks in each direction. The corresponding term is "sextuplication".
There are also instances of railway lines or sections with eight tracks, and cases with three or five tracks, however all experience similar upsides and downsides.
In quadruple track, trains are sorted in various ways in order to make maximum use of track capacity. These can include one or a combination of:
A faster express line and a stopping local line are separated, with each having a separate pair of tracks.
Construction of new double tracks dedicated to high-speed rail alongside existing conventional double track used by regional and local passenger trains and freight trains is a form of quadruple track. It increases the capacity of that route significantly, and allows for significant increases in inter-city high-speed train frequency with reduced travel times.
Long-distance inter-city rail and freight trains are separated from short distance commuter rail. This helps to prevent delays on one service affecting the other, and is commonly seen in metropolitan areas. Quadrupling may be necessary when a new commuter rail service begins to operate on an existing line. Sometimes the local trains have separate technology, such as electrical system or signalling, which requires strict separation, for example in Berlin or Copenhagen.
When a quadruple-track line divides to different destinations part way along, trains need to be sorted by their destination.
- Sorting by passenger/ freight
Passenger trains and freight trains can be separated with each different track.
A variation of this can be found on the quadruple track section of the Main Northern line in New South Wales between Waratah and Maitland where one pair of tracks are used exclusively for coal trains and the other pair are used for passenger trains and general freight. A similar process, but with all intercity and commuter passenger trains on the outer tracks and thru-freight trains on the inner tracks, was done by the Pennsylvania Railroad on its New York–Washington and Philadelphia–Pittsburgh mainlines prior to the takeover of operations by Amtrak and Conrail (and later Norfolk Southern). This is somewhat still done to this day by NS, CSX, and Conrail Shared Assets trains on Amtrak-owned trackage in the Philadelphia area.
Two separate double-track lines in proximity to each other, e.g., two double-track lines along opposite sides of a river, can operate as a quadruple track line. Examples of this can be found in Rhone in France and Rhine in Germany.
As it can be seen from the pictures below in the Gallery of diagrams, the four tracks can be paired either by direction (slow and fast in each pair) or by purpose (speed or direction in each pair). Pairing by direction allows the railway to interface to a double track more easily. With fast trains in centre, local stations can be on the outside, eliminating staircases for half the passengers. With slow trains in centre or when pairing by speed there can be a common platform for local trains with one staircase and one ticket booth.
Sometimes two of the tracks go more straight and with a little distance from the two other. This is a design decision when widening a double track section, and allows higher speed on the faster tracks.
Several lines radiating from Brussels are quadrupled, for instance the Ghent-Ostend line as far as Essene-Lombeek. Further quadrupling has recently been carried out as part of the development of the Brussels Regional Express Network. The building of high-speed lines has also led to quadrupling - for instance the HSL 2 high-speed line between Brussels and Cologne runs inside the local lines as far as Leuven. Meanwhile since 1934 Brussels and Antwerp have been connected by two separate pairs of double track. Fast trains normally use line 25, while line 27 serves slow trains. In places they run parallel, but at times diverge and cross over each other.
There are two places in Denmark with four tracks:
- Between Klampenborg and Høje Taastrup, through Copenhagen, Denmark, there are four tracks; two are for the separated S-trains and two for mainline trains; where the two tracks closest to Copenhagen (the oldest and central parts of Copenhagen) are reserved for S-trains (on much the lines this is the Northern and Western two tracks).
- Also between Høje Taastrup and Roskilde, where the two center tracks are for InterCity, long distance commuter trains (further than Roskilde or Ringsted), while the outer two tracks are for commuter trains to/from Ringsted or Holbæk. It has been suggested that the S-trains should continue from Høje Taastrup to Roskilde, but this plan was abandoned; partly due to Roskilde refusing the offer for fear they would become a suburb of Copenhagen, and partly due to construction costs which would exceed the advantages.
By definition German railway lines have one or two tracks. Where more tracks are running parallel to each other, they are considered two or more separate lines. Such routes include:
- The Berlin Stadtbahn, Germany, has four tracks. Two are for the separated S-Bahn and two for mainline trains.
- The 112 km long Hamm–Minden railway between Hamm and Minden in Germany is completely quadruple-track with separate tracks for freight and passenger trains.
- The 50 km long railway from Rastatt to Offenburg in Germany has four tracks.
- The Hohenzollern Bridge, with six tracks
- The line from Munich to Augsburg has four tracks and near Munich even more.
- The Rome–Naples high-speed railway and the Rome–Sulmona–Pescara railway in Italy combine to form a quadruple track section between Roma Prenestina railway station and Salone railway station.
- The Milan-Chasso railway and the Milan-Lecco railway run parallel in a quadruple track section from Milan to Monza.
- The main section of Ferrovie Nord Milano line between Milan and Saronno in Italy. Outer regional trains are segregated from the inner suburban trains.
There are some quadruple-track railways in the Oslo region. They are mostly two double tracks with slightly different routes, one older for local trains, and one newer mostly in tunnels for high-speed and regional trains.
- All of the mainline railway through Stockholm County (between Järna and Myrbacken north of Märsta, 83 km or 52 mi) has four tracks, sometimes having two routes. There are plans to widen Stockholm–Bålsta and Myrbacken–Uppsala to quadruple track with parts finished or under construction. After this, the Stockholm commuter rail would have its own tracks everywhere. The Swedish Transport Administration is currently planning on extending the quadruple track from a few kilometers north off Upplands Väsby to Uppsala Central Station within the upcoming decade. When having four tracks the local trans go in the middle, which allows a common ticket booth per station.
- The section between Malmö and Arlöv on the Southern Main Line has four tracks. As of 2018, an extension to Lund is expected to be finished in 2024. It will have local stations on the outside tracks, because staffed ticket booths are not used here.
- The 120 km long railway from Zürich to Olten contains long quadruple track sections from Zürich to Killwangen-Spreitenbach (Zürich–Baden line) and from Rupperswil to Aarau (Heitersberg line), currently being extended to Olten (Olten–Aarau line).
- Significant lengths of the West Coast Main Line, Great Western Main Line, South Wales Main Line, Midland Main Line, South West Main Line, Brighton Main Line, Chatham Main Line, South London line, Windsor Lines between Barnes railway station and Clapham Junction railway station and East Coast Main Line in Great Britain are quadruple track, with the remainder of the lines being double track. These lines are high capacity, intercity rail routes.
- The Metropolitan Line of the London Underground generally features a four-tracked alignment between Wembley Park and Moor Park. Additionally, from Wembley Park through Finchley Road it shares a four-track alignment with the Jubilee Line, with the Metropolitan Line providing fast (express) service in this section and the Jubilee Line making all local stops. Furthermore, the four-track alignment between the two lines essentially extends from Finchley Road to Baker Street. The two lines run parallel near each other, with the Jubilee Line making two additional stops and the Metropolitan Line running non-stop between the stations. The tracks on the Piccadilly & District Lines between Barons Court & Acton Town are also quadruplicated with the Piccadilly running fast and the District being the stopping line.
- The New York Central's Water Level Route across upstate New York was four-tracked in the majority as early as 1876, claiming to be the earliest 4-tracked steel main. This was extended to Buffalo by 1936. Financial troubles and changing traffic patterns caused this to be downgraded to a double track by 1975.
- The Metro-North Railroad's New Haven Line is four-tracked from Grand Central Terminal in New York City to New Haven Union Station in New Haven, Connecticut, while the system's Hudson Line features quadruplicated tracks for most of its length between Croton-Harmon and Spuyten Duyvil.
- Much of Amtrak's Northeast Corridor from Washington, D.C., to New Haven, Connecticut, is a four-track line, except for the segment between New Rochelle and the Sunnyside Yard in Queens, New York. In The Bronx, the Amtrak trains run separately from the former New Haven Line freight tracks. The right-of-way from Woodside, Queens, over the Hell Gate Bridge to Co-op City, Bronx, is three-tracked due to the presence of the single-tracked, freight-only New York Connecting Railroad. The Hell Gate Bridge was four-tracks before one of the freight tracks was lifted. The bridge was designed for an additional track on each side of the main arch for a trolley line.
- The Erie Lackawanna Railway had a four-track mainline on the former Erie Railroad, from its Pavonia Terminal in Jersey city to Suffern yard in Rockland County, New York. This allowed the separation of freight and commuter trains. The EL Rwy also inherited former Lackawanna four-track Boonton Main Line from Dover, NJ, to Delawanna (Passaic), NJ.
- The Central Railroad of New Jersey had a four-track main from the CNJ Terminal in Jersey City to Phillipsburg, NJ, across from Easton, PA.
- The Long Island Rail Road's Main Line is four-tracked from its East River Tunnels portal in Long Island City to Queens Village, NY.
- The Pennsylvania Railroad had a four-track mainline carrying freight from Pittsburgh to Harrisburg via the Horseshoe Curve (Pennsylvania). This was how the name Broadway Limited came about from the "Broadway of a 4-track main." Much of the route between Pittsburgh and Paoli has been downgraded to three or two tracks.
- Many lines of the New York City Subway are quadrupled – one of the few rapid transit systems in the United States to have extensive duplication. Hence, many express services are operated in the New York City Subway. Express trains and local trains are separated from each different track.
- SEPTA's Center City Commuter Connection in Philadelphia is quadruple track, as is about half of Philadelphia's Broad Street Subway.
- Reading Company's New York Branch between Neshaminy Falls and Yardley station was originally quadruple-tracked before being reduced to three tracks between Neshaminy Falls and Woodbourne station and two tracks between Woodbourne and Yardley. In 2016, the third track between Woodbourne and Yardley was relaid by SEPTA in order to separate SEPTA's West Trenton Line and CSX's Trenton Subdivision.
- The Coastal Railway between Tel Aviv Central and Herzliya. In 2020 construction started on an NIS 5.5 billion (US$1.5 billion in 2018 dollars) project to extend the 4 track section along about 10 km south from Tel Aviv Central to Tel Aviv HaHagana and from there to the Ganot/Shapirim interchange on the Tel Aviv–Lod Railway. In the future, four tracking of the Coastal Railway is also planned to extend north of Herzliya to Haifa in stages.
- Hankyu Railway in Osaka has a sextuplicated section between Umeda and Juso stations (2.4 km).
- Keihan Main Line in Osaka is quadruplicated between Temmabashi and Neyagawa Signal Box (~13 km).
- Odakyu Odawara Line in Tokyo is quadruplicated between Noborito and Yoyogi-Uehara Stations.
- Tokyu Toyoko and Meguro Lines in Tokyo run parallel beside each other between Hiyoshi and Tamagawa Stations.
- Seibu Ikebukuro Line in Tokyo is quadruplicated between Shakujii-koen and Sakuradai Stations.
- Tobu Tojo Line in Tokyo is quadruplicated between Wakoshi and Shiki Stations.
- Tobu Skytree Line in Tokyo is quadruplicated between Kita-Koshigaya and Kita-Senju Stations.
- Between Tokyo and Odawara (JR East) 83.9 km is paired by use (not including Shinkansen).
- Tokyo – Shinagawa 6.8 km: 6 tracks (8 if include Sobu-Yokosuka Line Underground)
- Shinagawa – Tsurumi 14.9 km: 4 tracks
- Tsurumi – Yokohama 7.1 km: 6 tracks
- Yokohama – Totsuka 12.1 km: 4 tracks
- Totsuka – Ofuna 5.6 km: 6 tracks
- Ofuna – Odawara 37.4 km: 4 tracks
- Between Tokyo and Omiya (JR East) is paired by use (not including Shinkansen)
- Tokyo – Akihabara: 6 tracks
- Akihabara – Ueno: 6 tracks
- Ueno – Nippori 2.2 km: 10 tracks (2 for Ueno Depot)
- Nippori – Tabata: 4 tracks
- Nippori – Oku: 4 tracks
- Tabata – Akabane: 4 tracks
- Oku – Akabane: 2 tracks
- (Nippori – Akabane 7.4 km)
- Akabane – Omiya 17.1 km: 6 tracks
- Between Kusatsu and Nishi-Akashi (JR West) 120.9 km (not including Shinkansen)
- Kusatsu – Kyoto 22.2 km is paired by direction: 4 tracks
- Kyoto – Umekoji – Mukomachi 6.4 km is paired by direction: 5 tracks
- Mukomachi – Ibaraki 21.8 km is paired by direction: 4 tracks
- Ibaraki – Suita is paired by use: 6 tracks
- Suita – Shin-Osaka is paired by use: 8 tracks
- Shin-Osaka – Osaka – Tsukamoto is paired by direction: 6 tracks
- (Ibaraki – Osaka 14.6 km)
- Shin-Osaka – Miyahara – Tsukamoto: 2 tracks
- Tsukamoto – Hyogo is paired by direction: 4 tracks
- Hyogo – Takatori is paired by direction: 5 tracks
- (Osaka – Takatori 38.2 km)
- Takatori – Nishi-Akashi 17.7 km is paired by use: 4 tracks
- Between Ochanomizu and Mitaka (JR East) 21.5 km is paired by use.
- Ochanomizu – Yoyogi: 4 tracks
- Yoyogi – Shinjuku: 8 tracks
- Shinjuku – Mitaka: 4 tracks
- Between Kinshicho and Chiba (JR East) 34.4 km is paired by use.
- Kinshicho – Nishi-Chiba: 4 tracks
- Nishi-Chiba – Chiba: 6 tracks
- Between Ayase and Toride (JR East) 29.7 km: 4 tracks/paired by use
- Between Osaki and Komagome (JR East) about 20 km is paired by use. (see Yamanote line)
- Osaki – Yoyogi: 4 tracks
- Yoyogi – Shinjuku: 8 tracks
- Shinjuku – Komagome: 4 tracks
- Between Souen and Heiwa (JR Hokkaido) about 9 km
- Souen – Sapporo is paired by use: 3 tracks
- Sapporo – Heiwa is paired by direction: 4 tracks
- Between Niigata and Kami-Nuttari (JR East) 1.9 km: 4 tracks/paired by direction
- Between Imamiya and Tennoji (JR West) 2.2 km: 4 tracks/paired by direction
- Between Inazawa and Nagoya (JR Central) 11.1 km/paired by use: 4 tracks
- Between Hiroshima and Kaitaichi (JR West) 6.4 km: 4 tracks/paired by direction
- Between Orio and Moji (JR Kyushu) 24.6 km
- Orio – Kokura: 4 tracks/paired by use
- Kokura – Higashi-Kokura 1.6 km/paired by direction: 6 tracks
- Higashi-Kokura – Moji is paired by direction: 4 tracks
- Besides JR companies, the following private railway companies in Japan run their own quadruple (or more) tracked sections:
The country never implemented a quadruple-track line throughout its history, but there are plans for sections of the North–South Commuter Railway (NSCR) to be quadruplicated.
- The NSCR will run alongside the Metro Manila Subway between FTI and Bicutan stations from ARCA Road to Mañalac Avenue. Length is 2,628 m (8,622 ft).
- A branch line to Clark International Airport will have a flyover interchange with the mainline, creating a 1,520 m (4,990 ft) quadruplicated section.
- A spur to the Mabalacat depot will diverge from the main branch, the latter heading underground. Length is 1,000 m (3,300 ft).