The Lapstone Zig Zag was a switch-back railway built near Lapstone between 1863 and 1865 to move goods and people up the steep Eastern side of the Blue Mountains. The whole project was plagued with problems and constantly required additions and changes. Eventually the whole thing was scrapped in place of an alternative rail line up Glenbrook Gorge and the construction of M4 motorway that is in use today. The line of the old track and the old Knapsack Gully bridge is now a popular walking track.
This walk is more about history than the bush, but it still gives great views and offers us an opportunity to see our beautiful city outside the urban sprawl. The walk follows where the tracks once stood, through sandstone cuttings, passing an old station that was called Lucasville, to the famous Knapsack Viaduct.
When it was built the viaduct was the largest in Australia, being 118 metres long and 36.5 metres high with 5 spans of 16.7 metres and 2 of 6 metres. Originally built to carry a single railway track, the bridge was later fitted with a new concrete deck, enabling it to carry 2 lanes of road traffic. It formed part of the Great Western Highway until being by-passed in the mid 1990's. Today it is used only by pedestrians, bicycles, emergency vehicles, and the Olympic Torch Relay in 2000.
The Knapsack Viaduct is signposted from the motorway (Emu Plains exit). From the carpark, near the junction of the old highway, take the footpath that follows the old railway and highway route to the viaduct. From here, a path descends below the stone arches, then down to Elizabeth Lookout.
The view from Elizabeth Lookout
You can also follow the stairs up to the old zig-zag railway formation at Top Points and the defunct Lucasville Platform. From here you can then follow the middle road down to Knapsack Quarry and the highway. On reaching the highway, continue south to Skarratt Park South, and the old Glenbrook Tunnel. The last train ran through the Glenbrook Tunnel in 1913. During World War 2 it was used by the RAAF to store 500lb bombs and then chemical weapons including mustard gas. Today it is used for growing mushrooms.
If you follow the highway's paved footpath it will take you back to the Knapsack Viaduct.
Remember: Before setting off on any walk, check the weather forecast and avoid walking in very cold, wet, windy or hot weather and on total fire ban days. Walk with at least one other person. Inform someone of your walking plans and what time you expect to return. Walk at a pace which is comfortable for you and your group.
What to wear: Enclosed shoes with a non-slip sole. A wide-brim hat and sunscreen.
What to carry: Drinking water and a snack, a first aid kit (even on short walks), insect repellent, a mobile phone (coverage may not be available in valleys) and a map. Enjoy.