Track harp

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Single track bundle or double track harp with one main track each on the left and right

A track harp , also track field or track group , refers to the division of a main track into several parallel tracks , which when viewed from the air is reminiscent of a harp . This can be found at multi-track stations and especially marshalling yards .

Track harp

Double track harp on the Proviso Yard of the C&NW (1942)

In a track ladder, the parallel tracks are designed so that all of them one after the other in a central soft road branched from the main track. This arrangement has the following partly positive, but partly also negative properties:

  • All turnouts have the same design.
  • All turnouts can be designed with a straight main track and straight frog .
  • The curve passed through (which also determines the total driving resistance) is twice the turnout angle.
  • The tracks have different usable lengths. Depending on the application, this can be an advantage (e.g. with overtaking tracks) or a disadvantage (generally with marshalling yards ).
  • The tracks are reached via different numbers of points , which results in different running times for the wagons to clear the track harp. This is a disadvantage in the automated operation of a marshalling yard with a waste mountain .
  • The wear and tear of the first switches is extreme, while the last switches are rarely used.
  • If the first switch is defective, all tracks cannot be reached.

The term track field is also used to denote an entire track system consisting of several track harps.

Track bundle

Track bundle of the direction group of the marshalling yard Kornwestheim

In modern marshalling yards, track bundles are usually used instead of track harps . Starting from the first turnout, further turnouts are inserted into both branches of each turnout until the desired number of tracks is reached. This results in a binary tree ; the number of tracks for each direction group is therefore often a power of two - e.g. B. the 64 tracks of the south-north direction group during the construction of the Maschenener marshalling yard (meanwhile reduced to 48 directional tracks ).

A bundle of tracks requires i. d. Usually the use of curved switches; in addition, the sum of the curves passed is greater than with the track harp.

Positive properties of a track bundle are the significantly shorter overall length and the approximately equal usable length of all tracks, which is particularly advantageous for marshalling yards with a waste mountain. All tracks are reached via the same number of points. Here, too, the first points are used more often than the last, but all points of the same branch level are used the same number of times on a statistical average.

See also

Individual evidence

  1. ^ A b Günter Schümberg: layout of the track plan . transpress, Berlin 1987, p. 127
  2. ↑ Th.Berndt: Eisenbahngüterverkehr , Teubner, Stuttgart 2001, ISBN 3-519-06387-5 , p. 93.
  3. ^ Günter Schümberg: layout of the track plan . transpress, Berlin 1987, p. 128