zig zag (railway)

A railway zig zag is a way of climbing hills in difficult country with a minimal need for tunnels and heavy earthworks. For a short distance (corrosponding to middle leg of the letter "Z"), the direction of travel is reversed, before the original direction is resumed. Zig zags suffer from a number of possible limitations.

length of train may be limited by length of track at top and bottom points.
reversing a train without running around engine to rear of train is hazardous.
time lost may be painful.

On the other hand, zig zags may be a quick and cheap alternative to expensive and slow to build tunnels.

Location of zig zags

Australia

Lapstone Zig Zag
Lithgow Zig Zag ( see Zig Zag Railway )

Pakistan

Khyber Pass

Peru

Zig Zag (Railway)

Location of zig zags

See also