History

Construction of the tunnel deviation commenced in April 1891, with a siding being built off the existing line, to a point above where the eastern portal would be located, for delivering construction materials. Construction of the tunnel necessitated diverting a creek across the top of the tunnel, just a few metres from the eastern portal, then down a cutting to join another watercourse. 

To save money, a ventilation shaft was not included, it being thought that 'the current of air passing through it should provide sufficient ventilation.'

The opening occurred on December 20, 1892, with the new route being hailed as a major improvement. Limitations soon became apparent.

A Sydney-bound goods train crosses Knapsack Creek & enters the tunnel. The line of the original (zig zag) railway can be seen running across the top of the photo (this is now the highway). This section of the original line was kept as a refuge siding. Later, it became the start of the construction tramway leading to the Glenbrook Gorge tunnel.
This scene is between today's native plant nursery & the RAAF base.
Photo: O.B. Bolton 

The tunnel is 31½ chains (634m) in length, passing beneath the ridge which carried the Zig Zag line & now the highway. It is 'S' shaped, with reverse curves of 15 chains (302m) radius & transition curves of 30 chains (604m) radius. Gradient is a steep 1 in 33, & seepage kept the rails wet. Wheel slippage was common. Inadequate ventilation meant that crews endured excessive quantities of smoke, steam & coal grit; not to mention their own perspiration. When a train stalled, the crew, exhausted by the fumes, had to back the locomotive out of the tunnel for another attempt.

In one instance, ".....passengers had to spend nearly an hour admiring the beauties of the interior of Glenbrook tunnel. Whilst traversing the tunnel the train stopped, & not until divided in two sections could progress be made. The stoppage is said to be due to the lack of sufficient head of steam." (The Nepean Times, 12/9/1912)

A New Route 

Problems with the steep, poorly ventilated tunnel, & the need to duplicate the line, led to the construction of today's Glenbrook Gorge route. Glenbrook Gorge opened as a single track only, with the old route being used by downhill traffic until duplication was carried out.  Continued.....  

Mushrooms and Bombs

The last train ran through the tunnel in 1913. Subsequently it was leased for mushroom growing, which continues to the present day. During World War 2 it was used by the RAAF to store 500lb bombs, then chemical weapons including mustard gas. The RAAF laid a concrete floor.

Heritage

Glenbrook Railway and World War Two Mustard Gas Storage Tunnel is now on the NSW state heritage register. Read the Glenbrook Railway and World War Two Mustard Gas Storage Tunnel heritage listing

Bushwalking (Hiking) 

At the eastern end, the old railway formation is reached from Skarratt Park, in Governors Drive, Lapstone, just beyond the highway exit.

After a few hundred metres, the line crosses Tunnel Gully Creek (look for the stone culvert near the left-hand gully wall) and the vegetation gets thick. Nutrient-rich run- off from 50 years of mushroom farming activities in the tunnel has turned the cutting into a hydroponic weed farm, full of quicksand-like mud.

In the late 1990's, the author abandoned an attempt to walk up the cutting, concluding that a machete & gumboots would be needed to reach the tunnel. A visit in mid 2000 revealed that some machete-wielding enthusiasts had recently cleared a path, & made a start on clearing privet & lantana.

The path leaves the railway bed short of the tunnel, ascending a narrow ridge separating the weed choked, water-logged cutting, from a water course. The author has followed the floor of the cutting up to the mouth of the tunnel, & found the mud to be deeper than his gumboots. You cannot enter the tunnel. Stick to the track, it's a lot easier!

Above the portal, a track leads south to the old tramway route, built to carry materials to the Glenbrook Gorge tunnel site. The tramway crosses Explorers Rd just east of the primary school, and continues to Bluff Lookout. Just west of the lookout, you can find remains of a funicular railway descending into Glenbrook Gorge. 

There is also a track to the end of nearby Lucasville Rd & Hillside Cres. From Hillside Cres, a footpath leads under the highway to the RAAF base - you can walk down Knapsack St to the zig-zag & Knapsck Viaduct.

Map... 
More bushwalking opportunities...

Conservation Management Plan

A Conservation Management Plan was prepared in 1993 for the Eastern Escarpment Committee of the Blue Mountains City Council. A copy is held at Springwood Library.

Glenbrook...