Zig Zag (railway)

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.
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The Zig Zag Railway is a heritage railway at Lithgow in New South Wales, Australia on the site of the famous Great or Lithgow Zig Zag which operated between 1870 and 1910. As built, the line formed part of the main line railway westward from Sydney across the Blue Mountains and served to lower the line from its summit into the Lithgow valley on the western flank of the mountains.
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