The Zig Zag Railway near Lithgow in Australia

Zig Zag Railway, bottom points the yards and storage sheds for the steam engines of the zig zag railway.
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.

The original plan, by the newly-appointed Engineer-in-Charge, John Whitton, had been to build a 3km tunnel, but this was beyond the resources of the state of New South Wales at the time. The zig zag alternative still required several short tunnels and some viaducts.

On the eastern side of the range, the first Blue Mountains Zig Zag (known as the Lapstone Zig Zag) opened near Glenbrook in 1867. It ascended Lapstone Hill on a gradient of 1:30 to 1:33 (~ 3 - 3.3%), which contoured up the side of the range with comparatively light earthwork.

By contrast, the Lithgow Zig Zag railway, built between 1866/69, required much heavier engineering, including four large rock cuttings, three fine stone viaducts with 30-foot semi-circular arches (originally four were planned, but one was built as an embankment instead) and a short tunnel (three tunnels were planned, but two were daylighted during construction due to leaks, becoming two of the four cuttings mentioned above). In the descent of the middle road, the line dropped 101 feet between the reversing points, being part of the 550-foot descent from Clarence, then the highest spot on the western line. The whole route had a ruling grade of 1:42 (~2.38%).

On Monday 19th October 1869 the Lithgow Zig Zag opened to traffic, completing the route over the Blue Mountains.

The Lithgow Zig Zag operated between 1870 and 1910. By then it had become an increasingly inefficient bottleneck owing to the growing traffic on the line between Lithgow and Sydney. It was eventually abandoned in 1910, replaced by the so-called Ten-Tunnel Deviation, a double tracked route with a ruling grade of 1:90. This is still in heavy use as the main line to western NSW and ultimately the trans-Australia line to Perth today.

For the next 65 years the tunnels and viaducts of the Great Zig Zag remained abandoned and silent except for some use as a tourist road and a walking track. In 1975 it was decided to restore the rails as a heritage railway, albeit on a different gauge (3 ft 6 in (1067 mm) instead of the original 4 ft 8½ in (1435 mm)). Rolling stock for the museum thus comes from states other than New South Wales – Queensland and South Australia in particular.

As of 2005 the railway is operated as the Zig Zag Steam and Diesel Tourist Railway.
[Source: Wikipedia]

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