Flying junction
Encyclopedia
Grade separation
Grade separation is the method of aligning a junction of two or more transport axes at different heights so that they will not disrupt the traffic flow on other transit routes when they cross each other. The composition of such transport axes does not have to be uniform; it can consist of a...
". A burrowing junction or dive-under is where the diverging line passes below the main line.
The alternative to grade separation is a level junction
Level junction
In U.S. railroad practice, a level junction is a railway junction that has a track configuration in which merging or crossing railroad lines provide track connections with each other that require trains to cross over in front of opposing traffic at grade In U.S. railroad practice, a level junction...
or flat-junction, where tracks cross at grade
At-grade intersection
An at-grade intersection is a junction at which two or more transport axes cross at the same level .-Traffic management:With areas of high or fast traffic, an at-grade intersection normally requires a traffic control device such as a stop sign, traffic light or railway signal to manage conflicting...
and conflicting routes must be protected by interlocked signal
Railway signal
A signal is a mechanical or electrical device erected beside a railway line to pass information relating to the state of the line ahead to train/engine drivers. The driver interprets the signal's indication and acts accordingly...
s.
Complexity
Infrastructure
Infrastructure is basic physical and organizational structures needed for the operation of a society or enterprise, or the services and facilities necessary for an economy to function...
to allow multiple routings among a variety of tracks without trains coming into conflict, in the manner of a highway stack interchange
Stack interchange
A stack interchange is a free-flowing grade separated junction between two roads.In countries where one drives on the right, left turns are handled by semi-directional flyover/under ramps...
.
High-speed rail
Nearly all junctions leaving or joining high-speed railHigh-speed rail
High-speed rail is a type of passenger rail transport that operates significantly faster than the normal speed of rail traffic. Specific definitions by the European Union include for upgraded track and or faster for new track, whilst in the United States, the U.S...
ways are grade-separated. On the French TGV high-speed network, the principal junction on the LGV Sud-Est
LGV Sud-Est
The LGV Sud-Est is a high-speed rail line, which links Paris' and Lyon's suburbs, in France. The inauguration of the first section between Saint-Florentin and Sathonay on 22 September 1981 marked the beginning of the re-invigoration of French passenger rail service.This line, subsequently...
at Pasilly where the line to Dijon diverges from the line to Lyon, and the junction on the LGV Atlantique
LGV Atlantique
The LGV Atlantique is a high-speed railway line running from Paris to Western France. It opened in 1989-1990. It divides into two parts at Courtalain, one going westward to Le Mans , the second one going southwestward to Tours .-Route:The line leaves Gare Montparnasse to cross Paris's southern...
at Courtalain where the line to Le Mans diverges from the line to Tours, are both fully grade-separated junctions equipped with special high-speed switches (points in British terminology) which permit the normal linespeed of 300 km/h (186 mph) along the direction of the mainline, and a diverging speed of 220 km/h (137 mph)..
The French LGV (Lignes à Grande Vitesse)
High-speed rail
High-speed rail is a type of passenger rail transport that operates significantly faster than the normal speed of rail traffic. Specific definitions by the European Union include for upgraded track and or faster for new track, whilst in the United States, the U.S...
network is large enough to contain four fully grade-separated high-speed triangles: Fretin (near Lille), Coubert (south-east Paris), Massy (south-west Paris) and Angles (Avignon). A fifth triangle, Vémars (north-east Paris) is grade-separated except for a single-track link on the least-commonly used side (southern end linking Paris Gare du Nord to Paris CDG airport).
Examples
Australia- Bowen Hills railway station in BrisbaneBrisbaneBrisbane is the capital and most populous city in the Australian state of Queensland and the third most populous city in Australia. Brisbane's metropolitan area has a population of over 2 million, and the South East Queensland urban conurbation, centred around Brisbane, encompasses a population of...
, Australia - Burnley railway stationBurnley railway station, MelbourneBurnley is a railway station in Melbourne, Victoria, Australia, located in the suburb of Burnley on the Lilydale, Belgrave, Glen Waverley and Alamein railway lines...
in MelbourneMelbourneMelbourne is the capital and most populous city in the state of Victoria, and the second most populous city in Australia. The Melbourne City Centre is the hub of the greater metropolitan area and the Census statistical division—of which "Melbourne" is the common name. As of June 2009, the greater...
, Australia - Camberwell railway stationCamberwell railway station, MelbourneCamberwell is a railway station which serves the Belgrave, Lilydale and Alamein lines in the eastern Melbourne suburb of Camberwell, Victoria, Australia...
in MelbourneMelbourneMelbourne is the capital and most populous city in the state of Victoria, and the second most populous city in Australia. The Melbourne City Centre is the hub of the greater metropolitan area and the Census statistical division—of which "Melbourne" is the common name. As of June 2009, the greater...
, Australia - Central StationCentral railway station, SydneyCentral Railway Station, the largest railway station in Australia, is at the southern end of the Sydney CBD. It services almost all the lines on the CityRail network, and is the major terminus for interurban and interstate rail services...
in SydneySydneySydney is the most populous city in Australia and the state capital of New South Wales. Sydney is located on Australia's south-east coast of the Tasman Sea. As of June 2010, the greater metropolitan area had an approximate population of 4.6 million people...
, AustraliaAustraliaAustralia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area... - Sandgate FlyoverSandgate FlyoverThe Sandgate Flyover is a grade separated railway flyover located in Sandgate, New South Wales. Its purpose is to allow coal trains to and from the Port of Kooragang to proceed without obstructing intersecting traffic to and from Sydney, as well as local Newcastle –-Maitland, etc., trains.With the...
, NewcastleNewcastle, New South WalesThe Newcastle metropolitan area is the second most populated area in the Australian state of New South Wales and includes most of the Newcastle and Lake Macquarie Local Government Areas...
- main line flies over coal branch line
France
(see "LGV Triangles" below)
United Kingdom
- Aynho Junction in AynhoAynhoAynho is a village and civil parish in South Northamptonshire, England, on the edge of the Cherwell valley about southeast of the north Oxfordshire town of Banbury and southwest of Brackley...
, Northamptonshire, UK - Worting JunctionWorting JunctionWorting Junction is a railway junction on the former LSWR route south of Basingstoke where the line divides to go towards Salisbury or Southampton.-History:...
near BasingstokeBasingstokeBasingstoke is a town in northeast Hampshire, in south central England. It lies across a valley at the source of the River Loddon. It is southwest of London, northeast of Southampton, southwest of Reading and northeast of the county town, Winchester. In 2008 it had an estimated population of...
, Hampshire, UK (NOTE that actual flyover (grade separation) is known as Battledown Flyover) - Cogload JunctionCogload JunctionCogload Junction is a railway junction in Durston, Somerset, England. It is where the 1906-opened London to Penzance Line via Castle Cary joins the original line that runs via Bristol...
near TauntonTauntonTaunton is the county town of Somerset, England. The town, including its suburbs, had an estimated population of 61,400 in 2001. It is the largest town in the shire county of Somerset....
, UK. - Weaver JunctionWeaver JunctionWeaver Junction is a railway junction on the West Coast Main Line . It connects Ditton to the WCML via Runcorn Railway Bridge and opened on 1 April 1869. Trains bound for Liverpool from London diverge from the WCML at this junction. Weaver Junction is the oldest flying junction in Britain....
near Dutton, CheshireDutton, Cheshirethumb|right|200px|Map of civil parish of Dutton within the former borough of Vale RoyalDutton is a civil parish and village within the unitary authority of Cheshire West and Chester in the ceremonial county of Cheshire, England. It is located approximately east of Runcorn.-External links:...
, UK (map) - the first ever
United States of America
- Tremont Street SubwayTremont Street SubwayThe Tremont Street Subway is a tunnel in Boston's subway system, and is the oldest subway tunnel in North America, opening on September 1, 1897. It was originally built as a tunnel to get streetcar lines off the streets, rather than a rapid transit line...
approaching the Pleasant Street InclinePleasant Street InclineThe Pleasant Street Incline or Pleasant Street Portal was the southern access point for the Tremont Street Subway in Boston, Massachusetts, which later became part of the Green Line .-History:...
in BostonBostonBoston is the capital of and largest city in Massachusetts, and is one of the oldest cities in the United States. The largest city in New England, Boston is regarded as the unofficial "Capital of New England" for its economic and cultural impact on the entire New England region. The city proper had...
, Massachusetts. - Broad Street Subway in Philadelphia has three flying junctions to un-built spurs on Stenton Avenue, the Roosevelt BoulevardRoosevelt Boulevard (Philadelphia)Roosevelt Boulevard , often referred to simply as "the Boulevard," is a major traffic artery through North and Northeast Philadelphia...
, and Passyunk Avenue. - Flying Junctions along the New YorkNew York CityNew York is the most populous city in the United States and the center of the New York Metropolitan Area, one of the most populous metropolitan areas in the world. New York exerts a significant impact upon global commerce, finance, media, art, fashion, research, technology, education, and...
-WashingtonWashington, D.C.Washington, D.C., formally the District of Columbia and commonly referred to as Washington, "the District", or simply D.C., is the capital of the United States. On July 16, 1790, the United States Congress approved the creation of a permanent national capital as permitted by the U.S. Constitution....
section of the Northeast CorridorNortheast CorridorThe Northeast Corridor is a fully electrified railway line owned primarily by Amtrak serving the Northeast megalopolis of the United States from Boston in the north, via New York to Washington, D.C. in the south, with branches serving other cities...
, and the Philadelphia-Harrisburg section of the Keystone CorridorKeystone CorridorThe Keystone Corridor is a Federal Railroad Administration "designated high speed corridor" with a 349-mile railroad line between Philadelphia, Pennsylvania and Pittsburgh, Pennsylvania with a top speed of...
, both converging together at Zoo Interlocking near 30th Street Station30th Street Station30th Street Station is the main railroad station in Philadelphia, Pennsylvania, and one of the five stations in SEPTA's Center City fare zone. It is also a major stop on Amtrak's Northeast and Keystone Corridors...
in Philadelphia. All were built by the former Pennsylvania RailroadPennsylvania RailroadThe Pennsylvania Railroad was an American Class I railroad, founded in 1846. Commonly referred to as the "Pennsy", the PRR was headquartered in Philadelphia, Pennsylvania....
and are now maintained by AmtrakAmtrakThe National Railroad Passenger Corporation, doing business as Amtrak , is a government-owned corporation that was organized on May 1, 1971, to provide intercity passenger train service in the United States. "Amtrak" is a portmanteau of the words "America" and "track". It is headquartered at Union...
. 39.97086°N 75.19848°W - The New York City SubwayNew York City SubwayThe New York City Subway is a rapid transit system owned by the City of New York and leased to the New York City Transit Authority, a subsidiary agency of the Metropolitan Transportation Authority and also known as MTA New York City Transit...
features many flying junctions across its system. - Flying junction connecting Metro-North RailroadMetro-North RailroadThe Metro-North Commuter Railroad , trading as MTA Metro-North Railroad, or, more commonly, Metro-North, is a suburban commuter rail service that is run and managed by the Metropolitan Transportation Authority , an authority of New York State. It is the busiest commuter railroad in the United...
's New Haven Line and Harlem Line, near WakefieldWakefield (Metro-North station)The Wakefield Metro-North Railroad station serves the residents of the Wakefield section of The Bronx via the Harlem Line, and it is the last station on the line before it crosses into Westchester County, New York. It is 12.6 miles from Grand Central Terminal and is located on East 241st Street...
station in the Bronx. - The Market Street Subway in San Francisco has a flying junction where streetcars from the J ChurchJ ChurchThe J Church is a Muni Metro railway line in San Francisco, California mainly serving the Noe Valley and Balboa Park neighborhoods, connecting them to downtown. It began as one of San Francisco's streetcar lines in 1917, and was converted to modern light rail operation with the creation of the Muni...
and N JudahN JudahThe N Judah is a Muni Metro line in San Francisco, California, so called as it runs along Judah Street for much of its length, named after railroad engineer Theodore Judah. It links downtown San Francisco to the Cole Valley and Sunset neighborhoods. It is the busiest line in the Muni Metro system...
lines join the main line of the subway. The subway portal is east of the intersection of Church Street and Duboce Avenue in the Duboce Triangle neighborhood, immediately north of a SafewaySafeway Inc.Safeway Inc. , a Fortune 500 company, is North America's second largest supermarket chain after The Kroger Co., with, as of December 2010, 1,694 stores located throughout the western and central United States and western Canada. It also operates some stores in the Mid-Atlantic region of the Eastern...
supermarket and south of the San Francisco branch of the United States MintSan Francisco MintThe San Francisco Mint is a branch of the United States Mint, and was opened in 1854 to serve the gold mines of the California Gold Rush. It quickly outgrew its first building and moved into a new one in 1874. This building, the Old United States Mint, also known affectionately as The Granite Lady,...
. - The Regional Transportation DistrictRegional Transportation DistrictThe Regional Transportation District, or RTD, was organized in 1969 and is the regional authority operating public transit services in eight of the twelve counties in the Denver-Aurora-Boulder Combined Statistical Area in Colorado. RTD is governed by a 15-member, publicly elected Board of...
in Denver has a flying junction between the Southeast Corridor and the I-225 Corridor. At this location, the Southeast Corridor is located on the west side of I-25 and the I-225 Corridor is located in the median of I-225. The grade separations of the junction are woven into the grade separations of the interchange between the two highways. (map) - All mainline connections on the Washington Metropolitan Area Transit Authority (Metro) rapid transit system use flying junctions. Adjacent to the Pepco power plant on Benning Road (near the Stadium-Armory station) is a large three track structure with a turnback pocket where the Blue and Orange lines meet. This would have been part of the Oklahoma Avenue station, had it been built. South of the King Street station in Alexandria is a series of tunnels where the Blue and Yellow lines meet. There are flying junctions at three underground rail stations: Rosslyn (Blue and Orange lines), L'Enfant Plaza (Green and Yellow lines), and the Pentagon (Blue and Yellow lines).
- Bloomfield (NJT station)Bloomfield (NJT station)Bloomfield station is a New Jersey Transit station in Bloomfield, New Jersey along the Montclair-Boonton Line. The station is located in downtown Bloomfield, the second within the municipality, just west of Bloomfield Avenue...
to eliminate level crossingLevel crossingA level crossing occurs where a railway line is intersected by a road or path onone level, without recourse to a bridge or tunnel. It is a type of at-grade intersection. The term also applies when a light rail line with separate right-of-way or reserved track crosses a road in the same fashion...
s
LGV Triangles
- Triangle de Fretin, Lille, France. Connecting Paris, Brussels and London. (map)
- Triangle de Coubert, Paris, France. (map)
- Triangle des Angles, Avignon, France. With two parallel 1.5 km (0.93205910497471 mi) viaducts. (map)
- "Triangle de Messy", Paris, France. Partial four-way junction. (map)
- Triangle de Vémars, Paris, France. (map).
External links
- WikiMapia link - aerial photo of Fretin triangle (mentioned above)
- Photo link - flying junction on Pennsylvania Railroad north of 30th Street Station, Philadelphia, Pennsylvania, United States
- Photo link - simpler flying junction at terminus of Market-Frankford transit line, 69th Street Station, Philadelphia, Pennsylvania, United States