Flying junction

A flying junction or flyover 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.

Simple flying junctions may have a single track pass over or under other tracks to avoid conflict; complex flying junctions may have elaborate infrastructure to allow multiple routings without trains coming into conflict, in the manner of a highway stack interchange.

On the French Lignes à Grande Vitesse (TGV) high-speed network, the principal junction on the LGV Sud-Est, at Pasilly where the line to Dijon diverges, and on the LGV Atlantique at Courtalain where the line to Le Mans diverges, are fully grade-separated with special high-speed switches (points in British terminology) that permit the normal line speed of 300 km/h (186 mph) on the main line, and a diverging speed of 220 km/h (137 mph).

[note 1] The LGV network has four grade-separated high-speed triangles: Fretin (near Lille), Coubert (southeast Paris), Claye-Souilly (northeast Paris) and Angles (Avignon).

Finland There are between 25 and about 40 flying junctions on Dutch railways, depending on how more complex examples are counted.

Flying junction: with a bridge, trains do not block each other
Fretin triangle in France: Each side is more than 3 km (2 mi) long. A grade-separated wye . TGV and Eurostar trains cross the junction at 300 km/h (186 mph).
Flying junction just east of Columbia station in New Westminster in Canada
Flying junctions flank both ends of Weesp railway station
The Uptown Hudson Tubes in Jersey City, New Jersey were built c. 1910 .
Zoo Junction in Philadelphia in 1977
Flying junction on the Tremont Street subway approaching the Pleasant Street incline in Boston