Great Zig Zag Railway Background
In the mid 1800s colonial settlement in Sydney was searching for ways to access the western parts of New South Wales (NSW) to allow for exapansion of the coloney, however the Great Dividing Range of mountains just to the west of Sydney appeared to present an impossible barrier to this expansion. A decision was made to build a railway line across the mountains and due to cost constraints it was decided to use two railway zig zag sections to ascend and descend the mountains and enable transport to the western regions of NSW. These zig zag sections became known as the Lapstone and Great Zig Zag sections and operated for approximately 40 years before being rerplaced.
Geography and Early Settlement
European settlement of New South Wales (NSW) started in 1788, with the landing of the First Fleet. Early settlement was restricted to the coast due to the seemingly impassable nature of the Great Diving Range, or Eastern Highlands. This mountain range is Australia's most substantial and the 3rd longest in the world. It stretches along the eastern coast for more than 3,500 kilometres (2,175 mi), from the northern tip of Queensland to western Victoria. It varies in width from about 160 km (100 mi) to over 300 km (190 mi). It is not a single mountain range but consists of a complex of mountain ranges, plateaus, upland areas and escarpments. Typically the highlands range from 300 m to 1,600 m in height.
The first settlers established themselves in the Sydney basin, which was bordered by the section of the Dividing Range called the Blue Mountains. The Blue Mountain's foothills start approximately 50 kilometres (31 mi) west of Sydney and extend westward as far as the Cox River. Consisting mainly of a sandstone plateau, the area is dissected by gorges up to 760 metres (2,490 ft) deep. The highest point of the range is Mount Werong at 1,215 metres (3,986 ft) above sea level.
Between 1788 and 1813, many people explored various parts of the mountains, but they were not able to find a easily passable way across the mountains. Official credit for crossing the Blue Mountains was eventually given to Gregory Blaxland, William Lawson and William Charles Wentworth. On 7 July 1814, construction of a road across the mountains was begun by William Cox.
Lithgow, on the western side of the Blue Mountains was established as a significant coal mining area. In order to increase the capacity to transport coal, and foodstocks, such as grain, cattle and sheep from the Western Plains to Sydney a railway across the Blue Mountains was proposed.
The first NSW railway was built in 1855 between Sydney and Parramatta. This demonstrated the benefit of rail transport and agitation for the building of railways to various parts of the state became an important objective for the Government of the day.
The railways department was under pressure to build a railway line over the Blue Mountains quickly and at a reasonable cost. John Witton, Engineer-in-Chief of the NSWGR, proposed the use of two Zig Zags in order to eliminate the cost of tunnelling through the mountains. Thus a zig zag was built at Lapstone, on the eastern side of the Blue Mountains to ascend the mountains, and one at Lithgow to descend the mountains back onto the western plains. The Lithgow, or "Great Zig Zag", as it became known was opened for traffic on October 18, 1869. When first opened, it was acclaimed as an engineering marvel around the world, and attracted sightseers from all over the world. Visitors were so numerous that the railways constructed a special platform at the bottom points of the Zig Zag to cater for this traffic. The line as opened consisted of some very steep gradients up to 1 in 33(Down), 1 in 42 (Up), and curves as tight as 8 chains (160 m). Over time these conditions limited the speeds and length of operation of trains.
Key Features of the Railway
The following description covers the section of Main Western railway line from Mt Victoria to BowenFels and includes the Great Zig Zag.
Stations and Major Sidings
Mt Victoria - Height: 3424' (1043.6m) Mileage: 75m 70c - is just east of the highest point on the western line and has been considered the outer suburban extremeity for Sydney.
Hartley Vale - Height: approx. 3320' (1011.9m) Mileage: 79m 53c - was a loading point for the the Hartley Vale shale oil plant.
Bell - Height: approx. 3501' (1067.1m) Mileage: 82m 07c.
Dargans Loop - Height: unknown Mileage: 84m 72c - was a temporary crossing loop that was built in the early 1900s to reduce section lengths and increase traffic volumes.
Clarence Siding - Height: 3658' (1115.0m) Mileage: 87m 44c.
Edgecombe Loop - Height: unknown Mileage: 89m 45c - was a temporary crossing loop that was built in the early 1900s to reduce section lengths and increase traffic volumes.
ZIg Zag Top Points - Height: 3362' (1025.4m) Mileage: 90m 33c.
ZIg Zag Bottom Points - Height: 3260' (994m) Mileage: 91m 35c.
EskbankHeight: unknown Mileage: 94m 31c. - was the original station built to service Lithgow.
Lithgow - Height: 3017' (919.58m) Mileage: 94m 68c - was built as a replacement to Eskbank.
Bowenfels - Height: 2973' (906.17m) Mileage: 96m 15c.
Clarence Tunnel - is located just west of Clarence siding and is a 1617' (493m) long tunnel on a falling 1 in 66 gradient towards the Zig Zag railway.
Bottom Tunnel - is located in the Middle Road of the Zig Zag railway and is 225' (69m) long.
Zig Zag Description
Construction of the Zig Zag was commenced in 1867 and was opened as part of the railway extension to Bowenfels in 1869. The Zig Zag was originally planned with 5 sandstone viaducts, and 3 tunnels. However, only 3 viaducts were built, the other 2 were replaced with stone removed from cuttings, and similarly only one tunnel was built. The first electrically detonated blasts in Australia took place here in January 1867 on Middle Road in order to open out one of the planned tunnels to create a cutting instead.
Between Clarence and near Eskbank, trains descend approximately 687' (209m) over 5miles (8km) on an almost continuous 1 in 42 falling gradient.
The zig zag works by allowing trains to ascend or descend on easier gradients then would be possible if the full descent was to be achieved in the 5 miles distance on the map. The train actually travels further then the 5 miles as it descends to Top Points and then reverses to the Bottom Points.
The Zig Zag railway was the scene of a number of accidents throughout its lifetime, the most notable occuring on Apr 4, 1901, when a locomotive went through the "stop block" at Top Points and was hanging precariously over valley below, until it could be recovered.
As traffic levels increased on the Mt Victoria to Bowenfels section, the Zig Zag increasingly became a traffic bottleneck and safety hazard. Finally in 1910 it was bypass by the construction of a deviation using 10 tunnels and sweeping curves to reduce the gradient to 1 in 66.