The Lapstone Zig Zag Walk
Updated: Sep 12
The Lapstone Zig Zag walk in Sydney’s Blue Mountains is a short (around 3km return) but beautiful walk that follows an old train line to a historic sandstone arched viaduct called Knapsack Bridge.
The walk starts at the parking area at the end of Knapsack Street in Glenbrook. The path is well maintained and for the first 1km or so it is not steep.
After walking for about 10 minutes you will come to the old Lucasville Station.
The station was built in 1877 for politician John Lucas who owned a house near here called Lucasville.
There’s not much left, but it is interesting to walk through the old railway cutting.
Another couple of minutes walk down the track will bring you to Siding Lookout (not much to see here as it’s been fenced off), at which point you start to descend towards the viaduct.
This is where the path starts getting steeper - firstly as a sloping path down, and then stairs.
You can choose to walk up onto the viaduct, on the path underneath the archways, or head all the way to the bottom and walk along the creek at the base.
The Lapstone Zig Zag was the first railway line into the Blue Mountains, and part of its construction was this beautiful bridge across the Knapsack Gully.
It was the first zigzag-designed railway in the world that was built as part of a larger main-line railway.
Building started in 1863 and it was officially opened in 1867, and then was closed in 1892.
From 1926 until 1993, the viaduct was part of the Great Western Highway (before the M4 was built). In 1995, the viaduct was opened as part of this walking track.
As you continue down the stairs, there are many spots to stop and have a great view of the bridge.
If you walk all the way down, you can follow the creek underneath the bridge, although there is a bit of rock scrambling to do.
The walk back to the carpark is more challenging as you go up all the stairs that you have just come down. Despite the stairs, it is a child-friendly walk, although I would recommend leaving strollers at the top of the stairs.
Depending on how long you spend exploring the bushland under the viaduct, the walk could take you 30 minutes, or a couple of hours.
There are no facilities at the carpark or along the way, and I recommend wearing decent shoes as the bottom section can be slippery.
If you have time after the walk and are in the mood for checking out another old bridge, we recommend visiting nearby Lennox Bridge - the the oldest stone arch bridge on the Australian mainland.