A flying junction is a railway junction at which one or more diverging or converging tracks in a multiple-track route cross other tracks on the route by bridge to avoid conflict with other train movements. A junction, in the context of Rail transport, is a place at which two or more rail routes converge or diverge A more technical term is "grade-separated junction". Grade separation is the process of aligning a junction of two or more transport axes at different heights ( 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 or flat-junction, where tracks cross at grade and conflicting routes must be protected by interlocked signals. In US Railroad practice a level junction (or in the United Kingdom a flat crossing) is a Railway junction that has a track An at-grade intersection is a junction at which two or more transport axes cross at the same Level (or grade) 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 drivers/engineers.
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Complexity
Simple flying junctions may have a single track pass over or under other tracks to avoid conflict, while complex flying junctions may have an elaborate infrastructure to allow multiple routings among a variety of tracks without trains coming into conflict, in the manner of a highway stack interchange. The TGV ( t rain à g rande v itesse, French for "high-speed train" is France 's High-speed rail service Eurostar is a High-speed train service in Western Europe connecting London and Kent in the United Kingdom, with Paris Infrastructure typically refers to the technical structures that support a society such as Roads Water supply, Wastewater, Power grids A stack interchange is a free-flowing junction between two or more roads that allows turning in all directions
High-speed rail
Nearly all junctions leaving or joining high-speed railways are grade-separated. On the French LGV high-speed network, junctions allow 300 km/h+ (normal linespeed) along the direction of the mainline, and a limit of 160 km/h for the diverging path.
The LGV network is large enough to contain four fully grade-separated high-speed triangles: Fretin (Lille), Coubert (south-east Paris), Messy (east of Paris) and Angles (Avignon). A fourth 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
- Weaver Junction near Dutton, Cheshire, UK [1]
- Aynho Junction in Aynho, Northamptonshire, UK
- Central Station in Sydney, Australia
- TGV Triangles
- Triangle de Fretin, Lille, France. Weaver Junction is a railway junction on the West Coast Main Line (WCML Dutton is a civil parish and village within the borough of Vale Royal in Cheshire, England. Aynho (formerly spelt Aynhoe) is a village in South Northamptonshire, England. Northamptonshire (or archaically the County of Northampton; abbreviated Northants Central Railway Station (also known as Sydney Terminal) is the largest Railway station in Sydney. Sydney (ˈsɪdniː is the most populous city in Australia, with a Metropolitan area population of approximately 4 Connecting Paris, Brussels and London. [2]
- Triangle de Coubert, Paris, France. [3]
- Triangle des Angles, Avignon, France. With two parallel 1. 5km viaducts. [4]
- "Triangle de Messy", Paris, France. Partial four-way junction. [5]
- Triangle de Vémars, Paris, France. [6].
See also
External links
- 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
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