Track looping
Track looping , or in Austria poking point , is the name given to an arrangement of two tracks of the same gauge, in which they are shifted into each other over a certain distance so that one rail of one track lies between the rails of the other. The distance between each rail of the one and the other track is usually minimal, so that the space requirement for both tracks is insignificantly larger than that for one track.
Track entanglements are used in double-track railways in relatively short bottlenecks - such as between buildings or through gates. Such bottlenecks can also arise for reasons of cost when a bridge or a short tunnel is only built on a single track. A track loop is sometimes set up only temporarily during construction work on one half of the route. Only one type of single-track operation is possible at the affected areas. Looping the track is less time-consuming than reducing it to one track using two points . Only two rail crossings are required. For long shared routes, however, switches are cheaper than four rails.
The entanglement is moderate because the cable guides of the two tracks cannot also be intertwined.
Track entanglements can therefore be found in some tunnels (e.g. the Gemmenich Tunnel ), on narrow bridges , landing bridges for railway ferries or in other narrow places; in the case of trams also where two-track routes would otherwise have to be run through narrow pedestrian zones or historic city gates (such as the Nauener Tor in Potsdam , see illustration on the right). In addition to Potsdam, they are also used in the tram networks of Braunschweig , Mannheim , Berlin , Dresden , Stuttgart , Prague , Düsseldorf , Amsterdam , Basel , Hanover , Kassel , Linz and Norrköping . There are also track entanglements in the railway network z. B. the Czech Republic .
When there is a signaled operation, it must be secured like a single-track line by cover points.
The sections with rails lying next to each other within stretched points (points with so-called "drawn-out points") resemble the four-rail section of a track loop. If two different railway systems are partially routed on the same route, the rails are also shifted into one another.
literature
Track looping. In: Viktor von Röll (ed.): Encyclopedia of the Railway System . 2nd Edition. Volume 5: Driver's Freight Tariffs . Urban & Schwarzenberg, Berlin / Vienna 1914, p. 352 f.
Karl Trautvetter: Electric trams and tram-like suburban and interurban trains . Springer publishing house Berlin Heidelberg GmbH, Berlin Heidelberg 1917.
Jörn Pachl: System technology of the rail traffic . Planning, controlling and securing rail operations, 8th edition, Springer Fachmedien, Wiesbaden 2016, ISBN 978-3-658-12985-9 .
