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. A more technical term is "grade-separated junction". A burrowing junction or dive-under occurs 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. 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 without trains coming into conflict, in the manner of a highway stack interchange. Flying junction without crossings Where two lines each of two tracks merge with a flying junction, they can become a four-track railway together, the tracks paired by direction. This happens regularly in the Netherlands (see Examples below). High-speed rail Nearly all junctions with high-speed railways are grade-separated. 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 on the main line, and a diverging speed of . The LGV network has four grade-separated high-speed triangles: Fretin (near Lille), Coubert (southeast Paris), Claye-Souilly (northeast Paris) and Angles (Avignon). A fifth, Vémars (northeast Paris), is grade-separated except for a single-track link on the least-used side, linking Paris Gare du Nord and Paris CDG airport. Examples Australia Bowen Hills railway station in Brisbane Burnley railway station in Melbourne Camberwell railway station in Melbourne Sydney Central Station Glenfield railway station, Sydney Strathfield railway station Sandgate Flyover, Newcastle – main line flies over coal branch line Goodwood railway station in Adelaide Canada Columbia station in New Westminster, BC – Expo Line branches for King George (top) and Production Way–University (bottom) Bridgeport station in Richmond, BC – Canada Line branches for YVR–Airport and Richmond–Brighouse Denmark Hvidovre, Copenhagen () Junction of M1 and M2 lines on the Copenhagen Metro Lunderskov () Roskilde, south of () Sydhavnen, Copenhagen () Vigerslev, Copenhagen () Finland Railway junction of two main lines at Kytömaa, Kerava