Zig Zag (railway)

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A railway zig zag, also called a switchback, is a way of climbing hills in difficult country with a minimal need for tunnels and heavy earthworks. 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.

Contents 1 Advantages 2 Disadvantages 3 Alternate names 4 Location of zig zags 5 See also

[edit] Advantages

The advantages of a zig zag include speed and relative cheapness of construction, with no need to worsen the ruling grade, compared to the alternative which almost certainly will require tunnels which are slow and costly to build. Where traffic is modest, a zig zag may well be a sensible long term solution.

[edit] Disadvantages

Zig zags suffer from a number of possible limitations:

• The length of a train will be limited by length of track at the top and bottom points.
• Reversing a train without running an engine around to the rear of the train is hazardous. Engines at the rear of the train help.
• The process is slow.

[edit] Alternate names

• In the United States, zig zags are called switchbacks.

[edit] Location of zig zags

• Argentina
  • Tren a las Nubes

• Australia
  • Kalamunda Zig Zag - 2 reversals
  • Lapstone Zig Zag - 2 reversals
  • Lithgow Zig Zag ( see Zig Zag Railway )
  • Mundaring Weir Branch Railway

• India
  • Darjeeling Himalayan Railway has six full zig zags, most are from the construction of the current railway but one was added in the 1940s and at least one other was used temporarily following storm damage, Narrow gauge

• Japan
  • Hakone-Tozan Line has three zig zags.

• Pakistan
  • Khyber Pass

• Peru
  • Cacray Zigzag on the Central Railway of Peru - with 9 switchbacks
  • PeruRail between Cuzco to Machu Picchu - 5 switchbacks

• Taiwan
  • Alishan Forest Railway

• United States
  • 8 Switchbacks at Cascade on GN - replaced by tunnel which was in turn replaced by a longer tunnel.

[edit] See also

• Zig Zags are often an alternative to a spiral though these may require long tunnels.
• Horseshoe curve (railway) - follows convenient side gully to gain height.
• Hillclimbing (railway)