Lost Railways:
Glenbrook and Lapstone Railway Deviations

Glenbrook and neighbouring Lapstone, in the foothills of the Blue Mountains, have plenty to offer the railway history buff. Within walking distance of each other are a monument to the Chief Engineer for NSW Railways, John Whitton, the father of NSW Railways who first brought the Great Western Line over the Blue Mountains; the picturesque sandstone Lapstone Viaduct over Knapsack Gully; the cuttings of a zig-zag railway; and one of Australia's oldest railway tunnels. All are located close to the Great Western Highway along the path taken by Whitton's first railway over the Blue Mountains. Commenced in 1863, the first section, between Penrith and Weatherboard (now Wentworth Falls), was brought into service on 13th July 1867.



The Lapstone Zig Zag

Engineer Whitton wanted to tunnel through the hill but a tight budget meant that a zig zag (or switch-back) was constructed. The cuttings for the zig zag still exist and can be reached by a path at the end of Knapsack Street, Lapstone. The site may be reached by a walking track at the end of Knapsack Street, Lapstone. This takes walkers along Top Road to Top Points past the remains of a railway platform, and thence to Middle Road. Highway upgrading has obliterated the site of Bottom Points, but a set of stairs and a walk along the new highway leads to Knapsack Viaduct.

Opened in 1867 it was sometimes known as the Little Zig Zag, being the first and smallest of Whitton's two Zig Zags on the route. The earthworks were carried out by William Watkins, and the track laid by Larkin and Wakeford. The device necessitated reversing the train up or down one of the three legs of the zig zag route. Gradients ranged from a steep 1 in 30 to 1 in 33. The Little Zig Zag remained in use until 1892 when it was bypassed via the Glenbrook tunnel with the same grade but it considerably speeded up travel times. The single track tunnel itself became a bottleneck and was replaced by the Lapstone Gorge Deviation in 1913 with a grade of 1 in 60.
UBD Map 162 Ref B 15



Old Glenbrook Tunnel

The 660.3m long Old Glenbrook Tunnel was built between April 1891 and December 1892 as part of a deviation which bypassed the Lapstone Zig Zag. To save money, a ventilation shaft was not included as it was believed the current of air passing through it would provide sufficient ventilation. This soon proved to be not the case. The gradient of the S-shaped single-line tunnel was, at 1 in 33, quite steep. Seepage kept the rails wet, leading to slipping and stalling. These shortcomings and the growing need for a second line led to the establishment of a new route through Glenbrook Gorge in 1913 which included a replacement tunnel.

A spur line was run from the main line near the eastern portal of old Glenbrook tunnel to the edge of Glenbrook Gorge, where a cable incline descended to the works site of a coal and shale mine. The spur line route is now a walking track which crosses Explorers Rd just below the primary school. The remains of the winding house and incline are signposted. Just west of Bluff lookout are the remains of the funicular railway descending into Glenbrook Gorge.

The tunnel was closed on 25 September 1913, and was utilised for growing mushrooms. During World War 2 it was used by the RAAF to store 500 LB. bombs and chemical weapons including mustard gas. The facility was known as No. 2 Sub Depot of No. 1 Central Reserve RAAF and was vacated by the RAAF after the war. It features in the 'Alcatraz Down Under' episode of 'Cities of the Underworld' on the History Channel.

The Old Glenbrook Tunnel remains closed and access to the entrances is difficult. The eastern portal can be reached via a walking track which commences at a reservoir alongside where Governors Drive branches off Great Western Highway. The track follows the path taken by the line to a point where the ground is too swampy and the undergrowth too thick to continue. It then leads up the side of the bank and across the top of the portal. The north portal is beside a lane off Barnet Street, Glenbrook.
UBD Map 182 Ref A 1


The Knapsack Viaduct

The route adopted by Whitton incorporated an impressive sandstone viaduct over Knapsack Gully. When opened in July 1867, the 5 span viaduct was the largest in Australia, being 104 metres long with the centre arch rising to around 38 metres above the creek bed. The contract for its construction was let to W. Watkins in March 1863 and the work was completed in 1865. It was originally built to carry a single railway track. In 1913 the railway line was diverted to its current path through Glenbrook Gorge and the bridge was abandoned. Downstream is another viaduct across Knapsack Gully which was built in 1913 to take the railway along its new route which it still follows today. This brick viaduct has eight arches.

With the development of the Great Western Road the earlier sandstone viaduct was purchased by the Main Roads Board and incorporated into the Road. It was reopened for two lanes of vehicular traffic on October 23, 1926. In 1938-39 the bridge was carefully widened to ensure that its appearance was not altered. Its use as a road bridge ceased in the 1980s when the highway was diverted to its existing route. A magnificent piece of workmanship, the bridge can now be viewed at close range via a walking track which crosses the bridge along where once ran the railway and later the roadway. For the best view and to appreciate the skills that went into its design and construction, take one of the tracks down into the gully and look up! Walking tracks through the bush in Glenbrook Reserve along the path taken by the railway lead to a memorial to John Whitton and the Lapstone Zig Zag.
UBD Map 162 Ref B 13





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  • A train passes along the current route through Glenbrook Gorge


    Remnant of a turnaround section on the Zig Zag railway


    Lapstone Lookout


    Mustard gas drums in bond after venting at the Eastern Cutting of Glenbrook Tunnel

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