World Library  
Flag as Inappropriate
Email this Article

Zig zag (railway)

Article Id: WHEBN0001133843
Reproduction Date:

Title: Zig zag (railway)  
Author: World Heritage Encyclopedia
Language: English
Subject: Spiral (railway), Ruling gradient, Lithgow Zig Zag, Lüttmoorsiel-Nordstrandischmoor island railway, Lapstone Zig Zag
Collection: Railway Track Layouts
Publisher: World Heritage Encyclopedia

Zig zag (railway)

Zig zag to cross the outer dyke on the railway serving the island of Nordstrandischmoor off the German North Sea coast
Zig zag of the Cecina-Volterra railway

A railway zig zag, also called a switchback, is a method of climbing steep gradients with minimal need for tunnels and heavy earthworks.[1] For a short distance (corresponding to the middle leg of the letter "Z"), the direction of travel is reversed, before the original direction is resumed.[2]

A location on railways constructed by using a zig-zag alignment at which trains have to reverse direction in order to continue is a reversing station.[3]


  • Advantages 1
  • Disadvantages 2
  • Hazards 3
  • Examples 4
  • References 5


Zig zags tend to be cheaper to construct because the grades required are discontinuous. Civil engineers can generally find a series of shorter segments going back and forth up the side of a hill more easily and with less grading than they can a continuous grade which has to contend with the larger scale geography of the hills to be surmounted.


Zig zags suffer from a number of limitations:

  • The length of a train is limited to what will fit on the shortest stub track in the zig zag. The Lithgow Zig Zag stub was extended at great cost in 1908, only to be completely deviated in 1910.[4]
  • Reversing a train without running an engine around to the rear of the train is hazardous. Top and tail or push pull operation with engines at the rear of the train helps.
  • The process is slow due to the need to stop the train after each segment and reverse the switch.
  • It is by nature a single track configuration.


If wagons in a freight train are marshalled poorly, with a light vehicle located between heavy ones (particularly with buffer couplings), the move on the middle road of a zig zag can cause derailment of the light wagon.[5]



  1. ^
  2. ^ Raymond 1912. "Switch-back development … necessitating the use of switches at these ends and the backing of the train up alternate stretches."
  3. ^
  4. ^
  5. ^
  6. ^
  7. ^
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.

Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.