Views and history on the Lapstone Zig Zag loop

After a morning of bush-bashing to find the long-forgotten Audrey Mountford cave in Warrimoo, I’m doing an easy Lower Blue Mountains bushwalk in the afternoon. The Lapstone Zig Zag loop involves a bit of road-walking, but is mostly on a mix of bushwalking tracks and firetrails through multiple bushland reserves. I was surprised that it wasn’t overly busy, although some sections of this mountain-bike and dog-friendly loop are quite popular – it’s not really a walk to do if you want solitude. But it does pass a few scenic lookouts and visits some of the historic road and railway history of the Blue Mountains.

There are many places you can start start & finish the Lapstone Zig Zag loop, and it can be done by train from either Glenbook or Lapstone station. I’m leaving my car Glenbrook Park, where there is plenty of parking, and doing the loop in an anti-clockwise direction. About 1.5km of walking along the road takes me to one of the many trails through Bluff Reserve, which starts at the end of Brook Road. The trail passes the Faerie Tree, a significant Glenbrook landmark that surprisingly does not appear in any guide books of the area…

Bluff Reserve / Darks Common Reserve

After you enter Bluff Reserve, it’s only about a hundred metres to Chalmers Lookout, which offers a nice (but not very spectacular) view to the south over the surrounding bushland and Glenbrook Creek below.

The bushwalking track winds around the top of the headland, passing a few more informal vantage points.

The next fenced vantage point is Ross Lookout, which offers a view towards the east over Glenbrook Gorge.

The track then crosses a small gully, where a funicular was used in the construction of a new route for the Blue Mountains railway line in 1911. A spur line branching off the old railway line went to the edge of the escarpment, and a cable incline descended to the works site. The remains of the (signposted) winding house base is located near the track.

The Lapstone Zig Zag walk now follows the old tramway route to Explorers Road; a very small detour takes you to an informal lookout above Glenbrook Gorge and the railway line. This is one of my favourite lower Blue Mountains vantage points: looking almost straight down into the rugged Glenbrook Gorge, you can just make out the tiny bushwalkers making their way down Glenbrook Creek. When you are inside the gorge it feels like you are miles from civilisation – yet as you can see from here, you are less than a hundred metres from the train line.

A bushwalking trail continues along the edge of the escarpment before looping back up to the Tramway Route, offering more views down Glenbrook Gorge…

…or you can backtrack a short distance to continue along main walking and biking track. Either way, you’ll end up back on the Tramway Route which traverses the Darks Common Reserve (named after Michael and Jill Dark, local residents who fought in the 1970s to stop a housing development and to have the area set aside as a public reserve). Some parts of the track have been cut through solid sandstone, to provide a level route for the railway.

Railway Reserve and Glenbrook Tunnel

The Tramway Route crosses Explorers Road, where it enters Explorers Road Reserve (a most original name!) A network of bike tracks makes the area a bit confusing, but continue heading northwards on the main trail…

…which eventually drops steeply down to Tunnel Gully.

The track follows the top of Tunnel Gully, past the eastern end of the Glenbrook Tunnel – also known as the Lapstone Hill Tunnel – as it follows alignment of the old railway line. The 660.3m long tunnel was built from 1891-1892 as part of the First Deviation (used from 1892-1913), bypassing the original Lapstone Zig Zag railway. A steep incline and water dripping from the tunnel roof which caused the engines to slip meant that this route was soon replaced (in 1913) by the Second Deviation.

In 1913 the tunnel was leased by Herbert Edward Rowe to grow mushrooms, then used by the RAAF during World War 2 to store bombs and chemical weapons, including mustard gas. The Glenbrook Tunnel was used again for mushroom-growing after the chemicals were removed and disposed of by 1949. The tunnel was added to the NSW State Heritage Register on 5 August 2011, and in 2021 it was proposed that the tunnel be transformed into a walking and cycling path which will connect Penrith to the lower Blue Mountains.

The bushwalking and cycling track continues through what is now Railway Reserve to reach Governors Drive, where there is a very short road-section before a flight of steps takes you into the southern end of Knapsack Reserve.

Knapsack Reserve and the Zig Zag Railway

This well-signposted section of the Lapstone Zig Zag loop is the most popular, with the bushwalking track ascending to the Quarry Lookout (you bypass this if you take the cycleway option). This vantage point gets my vote for the least impressive lookout of the Blue Mountains, offering a birds-eye view of the remains of what was Knapsack Quarry, which provided the sandstone used to construct the Knapsack Viaduct.

The walking track soon merges with the cycleway, which follows the route of the original Lapstone Zig Zag railway through of cutting in the sandstone. Opened in 1867 and sometimes referred to as the “Little Zig Zag”, construction of the section between Penrith and Weatherboard (Wentworth Falls) began in 1863 and was completed in 1867. It was designed by John Whitton, the Chief Engineer for NSW Railways, who wanted to tunnel through the hill, but due to budget constraints was forced to adopt a “zig zag” design. Trains would have to reverse up or down one of the three legs of the zig zag route.

Near the top points is the remains of Lucasville Station, opened on 15 April 1878 for Mr John Lucas MP who lived nearby.

The cycleway continues up to Top Points Lookout, which is the upper of the two sidings where trains would reverse direction as they “zig-zagged” up (or down) Lapstone Hill. Through the trees is a view of the Knapsack Viaduct, which eventually rendered the Lapstone Zig Zag obsolete, and beyond it the New Knapsack Viaduct which is used today.

Knapsack Viaduct

A bushwalking track descends to the Knapsack Viaduct, which spans Knapsack Valley – you can follow a track that goes under the viaduct, or walk across the old railway and roadway.

Now, I had planned to stay on track for this bushwalk… but as well as the two sensible options, a third, rough track descends in a westward direction into the gully. The track soon reaches a very deep hole, covered by a very big wire grill… this turns out (I discover later) to be the Lapstone Creek Hole. Or more specifically, a 32m deep hole through solid rock, which allowed the counterweight on the crane used to lift the sandstone blocks to make the viaduct to go up and down.

The track ends here, and I follow the creek downstream, passing under the impressive sandstone viaduct. Knapsack Viaduct was the largest in Australia when opened in July 1867, and was originally built to carry a single railway track – the Second Deviation of the Blue Mountains rail route. It was used for rail until 1913 when the line was diverted a third time to its current route, and then used for the Great Western Highway from 1926 to the 1980s (it was widened in 1938-39, but in a way that didn’t alter its appearance).

I rejoin the walking track on the downstream side of the viaduct, which climbs up the northern side of Knapsack Gully.

From the bottom of the viaduct it’s just under a kilometre of constant uphill walking – although it’s only about a hundred metres of elevation gain in total. (I don’t see anyone else on this section of the walk; most people follow the walking and cycling path along the Former Great Western Highway.

At the top of the valley the track passes Elizabeth Lookout, named after Elizabeth Skarrat née Norris, the wife of a Blue Mountains Shire Councillor. It offers a not-very-exciting view over the Cumberland Plain to the west.

From here there are a few mountain-biking and walking tracks that criss-cross Knapsack Reserve, but whether you follow the main cycling trail or take a narrower, secondary trail you’ll end up Marges Lookout. This fenced lookout offers a sweeping view over Emu Plains and the artificial lakes created for the 2000 Sydney Olympics rowing sites.

A level mountain-biking and bushwalking track follows the edge of Knapsack Reserve, just above Mitchells Pass which eventually comes into view near Lennox Bridge. Mitchells Pass formed part of the main route across the Blue Mountains for almost 100 years, before the highway was route across the Knapsack Viaduct in 1926.

Lennox Bridge, completed in 1833 by David Lennox using unskilled convict labour, is the oldest stone arch bridge on the Australian mainland.

From Lennox Bridge, the track follows the Old Mitchell Pass, which was the vehicular route used until Lennox Bridge was completed.

The escarpments at the eastern and western ends of the Blue Mountains proved the greatest challenge to Colonial road builders. Mitchell’s Pass was the third vehicular route constructed on the eastern escarpment of the Blue Mountains. Construction commenced in 1832 and was finished in 1833 on a route proposed by the Colonial Surveyor General Thomas Mitchell. The pass at first had a detour along the present Brookside Creek until the construction of a bridge over the deep gully at the north of the creek was constructed to the design of David Lennox. The southern detour, referred to in this report as the 1832 bridle trail, survives today as a walking track along the creek.

Blue Mountains City Council, Mitchell’s Pass Historic Precinct Conservation Management Plan

The old road follows Brookside Creek fairly closely; where the creek crosses a wide rocky platform there is an Aboriginal axe grinding groove site.

There’s another network of mountain biking trails towards the end of Old Mitchell’s Pass, but stay on the main and you’ll eventually reach a trailhead near Olivet St. A side-track takes you to Barnet St, where the final kilometre to close the loop is on roads.

The entire loop is about 13.5km, and there are some variations you can do make it a little shorter and easier (like following the top of the Knapsack Viaduct rather than dropping down into the gully – although that means you’ll miss one of the best bits of the walk!) The highlights of the Lapstone Zig Zag Railway walk are the Glenbrook Gorge lookouts, the old Glenbrook Tunnel (which you’ll one day be able to walk through) and the Knapsack Viaduct.

Getting to the Lapstone Zig Zag Railway loop

There are many places you can start the Lapstone Zig Zag Railway loop, including near Glenbrook Park, at the end of Emu Road near Bluff Reserve (note there is no parking at the end of Brook Road) or even near Lennox Bridge along Mitchells Pass (limited parking). If travelling by train, the easiest access is from Glenbrook Station, where a 0.5km walk up Ross Street will get you to Glenbrook Park.

More information

• Visit Sydney – Lost Railways: Glenbrook and Lapstone Railway Deviations
• Australian Railway History – Conquering Lapstone Hill [PDF]
• Blue Mountains City Council – Mitchell’s Pass Historic Precinct Conservation Management Plan [PDF]
• Take a Break in the Blue Mountains – Lapstone Zig Zag Historic Walk (pp. 36-41)