The zig zag railway
The Zig Zag Railway was built between 1866 and 1869, and acclaimed a major engineering feat of its time. It was constructed to enable produce to be taken to Sydney from the prosperous farming areas beyond the Blue Mountains and to develop the coal and iron ore deposits found in the Lithgow Valley.
The prodigious feat of bringing the railway from the top of the mountains to the valley below was accomplished by John Whitton, Chief Engineer of the NSW Government Railways. At the time The Great Zig Zag was regarded as one of the engineering wonders of the Victorian age.
A by-product of such construction was the development of locomotive boilers which could cope with steep slopes and this led to the construction of mountain railways in other parts of the world, particularly the Americas.
The Zig Zag consists of a series of sloping tracks forming the letter "Z" with reversing stations at Top and Bottom Points. The Top part of the 'Z' is Top Road, the middle part is Middle Road. Bottom Road is now only a short section leading to the Depot.
Trains travel down each part of the "Z" at a gradient of 1 in 42 which can safely be negotiated by a loaded train.
http://www.zigzagrailway.com.au/history/lineside.html
