Bridges

Knapsack Gully Viaduct – Lapstone Hill

Background
With the crossing of the Blue Mountains and the subsequent opening up of vast tracts of land west and south, there was an urgent need for quick, safe and reliable transport at a reasonable cost. The extension of the railway to Bathurst was felt to be necessary. The Bathurst Road route from the Nepean River to Mt. Victoria was recommended as the best railway location and arrangements were put in hand for its construction.

knapsack viaduct

Construction
In ascending the first range of the Blue Mountains, the Engineer-in-Chief, John Whitton, was compelled to cross the deep ravine of Knapsack Gully at the head of Jamison Creek. For this he designed a sandstone arched viaduct, 5.5m in width, to carry a single line of rail. The contract for its construction was let to W. Watkins in March 1863 and the work was completed in 1865. Its length was 118 metres and its height at the centre 38 metres above the creek bed.

Closure and reopening
The viaduct fell into disuse in 1913 when the railway line closed on the completion of the Glenbrook Gorge Deviation and was unused until 1926 when it was taken over by the Main Roads Board and incorporated in the Great Western Highway. To cope with the increasing traffic it was widened to 9 metres in 1939. A plaque to honour the memory of John Whitton was affixed to the north-east corner of the viaduct in 1926.


Lapstone Zig Zag

Background
In 1856, a party of sappers from the Royal Engineers were surveying the best route for the railway from Sydney to Bathurst. The major problem was where to cross the Blue Mountains. The three alternatives seemed to be (i) the Grose Valley; (ii) Bell’s Line Ridge; (iii) Bathurst Road Ridge. The third was decided upon, but there remained the problem of ascending the first stage to the present Glenbrook. The solution was the Lapstone Zig Zag being an example of the type of railway construction designed to negotiate very abrupt ascents. The line was laid in the form of a ‘Z’ with reversing joints where the line doubles back to enable the train to reverse its direction.

Building the Zig Zag
The design and construction of the Zig Zag was inspired by John Whitton, a Yorkshireman who in 1856 was appointed the Engineer-in-Chief of the New South Wales railways. Whitton had preferred the railway to rise along the mountainside from Emu Plains, tunnel through Lapstone Hill and emerge near the swamp at the head of Knapsack Creek, but because of the expense of this plan the less costly Zig-Zag was constructed.
To reach the ascent at the Lapstone Zig Zag, the Nepean River was crossed at Victoria Bridge and the Knapsack Gully was bridged with a stonework viaduct, both designed by Whitton. So on the 11th July 1865, the line was opened as far as Weatherboard (now Wentworth Falls).

Glenbrook Tunnel
The railway was extended to Bathurst in 1876. The predictable increase in traffic meant that a bottleneck was caused by the time-consuming reversal of trains up and down the Lapstone Zig Zag. This was overcome by the first Glenbrook Tunnel, opened on 8th December 1892, which emerged at the top of Knapsack Creek. This tunnel had its drawbacks though. It was cramped and single lined, on a steep gradient and was often wet and slippery due to water dripping from the roof. The train crew and passengers were often inconvenienced by smoke and steam on the slow up-hill journey through the length of the tunnel.

New direction and tunnel
Finally, in 1913, the present route was opened with the railway proceeding lower down the Lapstone Hill and negotiating a tunnel of lesser gradient than the original Glenbrook tunnel. It was a double-tracked tunnel and emerged above the Glenbrook Gorge to arrive at the present site of Glenbrook station. The age of the motor car prompted the original Knapsack Viaduct to be opened for vehicular traffic in 1926 with the remaining (now abandoned) formations of much of the original railway line on the eastern face of Lapstone Hill being used in the construction of the Great Western Highway from Emu Plains to Glenbrook. The first Glenbrook Tunnel has been used for mushroom growing and, during the Second World War was used to store non-explosive weapons components. In the present age, the land around about the Zig Zag is a popular recreation and bushwalking area.


Lennox Bridge

Background
The first road up the eastern slopes of the Blue Mountains, built by William Cox (1814-15), was in Governor Macquarie’s words “pretty steep and sharp” and was found to be subject to serious washways. This was superseded in 1824 by what was known as the Bathurst Road (now Old Bathurst Road). It avoided watercourses, but its grade was very steep and this rendered it hazardous to travellers. Early in 1832, Surveyor-General Mitchell suggested a third road about midway between the other two. This was a marked improvement on its predecessors, its grade being gentler and its curves much broader. The work went well until they reached the formidable gully through which Lapstone Creek flows. A superior stone bridge was required, but there was a scarcity of experienced stone masons and bridge builders in the colony. This problem was resolved when Mitchell met David Lennox, a master mason with 20 years experience in the supervision of bridge construction in Britain. David Lennox appointed Lennox was appointed Sub-Inspector of Roads on 1 October, 1832, and set to work on a semi-circular stone-arch bridge over Lapstone Creek. The bridge work partly consisted of 20 convicts selected by Lennox from the road gang and trained by him in stone work as they went along.

Lennox Bridge

Bridge completed
The bridge was completed in July 1833 – the first scientifically designed stone-arch bridge on the Australian mainland. A unique feature of the bridge lies in the fact that while its western side is a straight line, its eastern is a graceful curve. Lennox Bridge formed part of the main route to the west until the Great Western Highway was channelled across the Knapsack Viaduct and along the old railway route to Blaxland in 1926. Closure of bridge During the 1950’s particularly, the bride suffered from the increasing load of modern cars and heavy vehicles. Damage to the stonework eventually rendered it structurally unsound and it was closed to vehicular traffic in 1962.

Restoration
Restoration work began in the late 1970’s – designed so as to recreate the shape and appearance of the original bridge while at the same time providing the structural strength necessary to prevent damage by modern traffic. The Bridge was officially reopened to traffic on 14th December, 1982.


Victoria Bridge

Nepean River, Penrith Early crossing and first bridges
In the very early days, the Nepean was crossed at Emu Ford and later a punt service was begun across the river at a location just south of the present bridge. The first move for a road bridge at Penrith was and Act dated 15 December, 1851, providing for a structure costing £6,000. Owing to a general increase in costs and wages about this period due to the Gold Rush conditions, it was necessary to pass another Act in 1854 to increase the capital to £20,000. The bridge was constructed but was destroyed by floods in 1857. Reconstructed, it was again destroyed in 1860. It was decided to defer the restoration of the road bridge because plans were almost complete for the extension of the railway across the river and over the mountains and it was considered that part of the railway bridge could be used by road vehicles.

Victoria bridge

Victoria bridge
Together with its sister bridge at Menangle, this bridge is one of the oldest and finest railway bridges in the State. One legend has it that the Victoria Bridge was originally constructed for the Crimea and when not required was bought by the N.S.W. Government. Not so! The bridge was designed in the colony by the Engineer-in-Chief, who sent the design to England for checking by John Fowler. The structure comprises three spans of continuous girder construction resting on two intermediate piers. It is 181 metres long with an effective road width of 7.77 metres, the side members being 3.96 metres deep. One interesting feature of the structure is that it is about 2 metres higher than was originally intended. Before the final designs for the piers were completed, severe floods indicated that it would be desirable to raise the level, and the designs were adjusted. This explains the provision of the rising 1 in 200 grade on each side of the bridge. The extra size was soon justified because the 1867 floods which undermined the western timber approaches, rose to within 1 metre of the spans at flood height. Had the spans not been erected at the higher level, the flood of water would probably have damaged the structure. The contract for the construction of the piers of the Victoria Bridge was let to William Tyler in November, 1862, but due to the floods in 1863 and 1864, little progress was made and Mr. Tyler surrendered his contract in August, 1864. A tender for the completion of the work was let to Mr. W. Watkins in October 1864 for £44,658. He completed the work in September 1865. Tenders for the fabrication and erection of the steelwork for the bridge were called in December 1864, Messrs. Peto, Brassey and Bett agreed to supply and erect the spans. All spans were stacked ready for erection and the necessary staging prepared by the end of 1865. The 1867 flood caused much damage and the new bridge was out of service for a considerable time. The punts employed for crossing the river following the 1860 disasters, were washed from their moorings in June 1867 and lodged against the piers supporting the timber approach spans. This incident undermined the piers and caused the decking to sink about a half metre. As a result, John Whitton, the Engineer-in-Chief, decided to replace several of the spans with an extra iron span of 41 metres. This work was carried out by day labour in 1869. The effective width of the bridge was only 7.77 metres so there was only room for a single vehicular track and railway. To keep the two forms of transport clear, a galvanised iron fence was erected down the centre of the bridge. In order to prevent the larger and heavier road vehicles from striking and damaging the fence, two channel strips were laid to form wheel guides. In addition, a warning system was introduced so that horse-drawn vehicles could be clear of the bridge before a train crossed.

New railway bridge added
The introduction of heavier locomotives and trains indicated that a double track was needed. The viaduct was renewed in steel and a new railway bridge constructed. The foundation work was started on 1 June, 1904 and completed in April, 1906. Work on the superstructure was begun in March, 1906 and the bridge and viaduct, consisting of 53 spans of 9 metres each were brought into use on 2 June, 1907. The bridge consists of five spans, four of 58.9 metres and one of 36.8 metres. An interesting feature in the design is that although one span is shorter than the others, the height of the trusses has been kept constant for appearance sake. On the opening of the new railway bridge, the Victoria Bridge was altered to provide for a double line of road traffic; a footpath about 1.5 metres wide was provided along the southern side.

Railway bridge