This was also the period where precast concrete was used in the construction of buildings and other infrastructure.
Pre cast concrete was first used in the construction of the station building at Lake Cargelligo which was opened for traffic on 13th November 1917. This was evidently a trail as the for the next 2 years the lines that were opened did not use this material in their construction. It was not until the opening of the Kempsey to Macksville section of the North Coast line on 1 July 1919 that the material was used again. This time every branchline built through to 1932 used the material.
The construction of the water tanks went through a change at the same time and the panels used in to tank began to be constructed by the PerWay Workshops in Newcastle. The standard set of plans were also reissued at the time.
The catalyst for all of this change was the responsibility for new lines reverting back to the railways after 23 years with the Public Works Department. While new designs (the precast buildings in particular) were issued the over-riding reason for these were (cost and time). The new designs and materials enabled large batches of part to be created for various locations without reference to the actual site.
Wile the structures were similar to those previously built there were four distinct changes or new designs that occurred during this period:
- Large Concrete Bases
- New Design of Timber Stands
- American Type Jibs
- Tank Panels made by Per Way Workshops
The Concrete Bases
In 1917 the railways performed an experiment with the method of construction of the stand. Instead of the normal style of concrete footings a foot or so high large four legged arch structures were used. Formwork was built, the steel columns placed and the concrete poured. The result was an extremely stable stand.
Three of the type were constructed over a short period in 1917 at Ungarie and Lake Cargelligo on the Wyalong to Lake Cargelligo section and Wirrinya (construction name Coolana) on the Caragabal to Forbes section. All three structures were built as single tier 20000 gallon tanks with Lake Cargelligo being provided with a jib. Wirrinya gained an additional tier, making its capacity 40000 gallons in August 1926.
The arch concrete structures were in total 13’ high and approximately 11’ wide. The example at Lake Cargelligo being slightly different than the other two examples in that the piers extended a further 4” above the arch although it seems as they addition was added some time after the initial construction. Above the concrete structure the stand was similar to those that were constructed previously.
The railways only built three of these types of stand. It was no doubt an experiment that was quickly found to be not suitable primarily due to the time taken to construct the stand. While all three tanks were built in open and possibly wind blown areas there are many tanks built after these there that are in similar open areas that did not have this type of stand.
|Lake Cargelligo, 21 August 1998|
|Lake Cargelligo, 21 August 1998|
|Lake Cargelligo, 21 August 1998|
|Wirrinya, 29 July 1993|
New Timber Stand Design
In late 1918 there was a shift away from stands made of steel and a return to those made of timber. The new stand while similar to previous timber stands but was the diagonal bracing was external of the timber piers rather than inside the piers.
The foundations of the stand were 2’6 square concrete with a 1 ¾” diameter and 1’9” long steel rod embedded in the centre of each foundation. 12” square timber piers were centred on the steel rod with 26’ long 12” square bearer resting on the piers. 12” by 6” joists resting on the bearers and supported the tank. In the case of the 20000 and 40000 gallon tank there were 16 piers, 4 bearers and 7 joists. The piers were braced in sets of four with 6” x 3” diagonal braces between the piers. Where the bracing crossed a 1” diameter galvanised pipe was used to tie them together. The stand was held together by 7/8” diameter bolts of various lengths. Strap bolts were used to connect the piers and the bearers.
The new stand was first used in late 1918 at Euabalong West on the Condobolin to Trida. This was followed by the following tanks:
- Warrell Creek Tank (Eungai – Macksville)
- Broken Hill
- Rankins Springs
- Mole Creek Tank
|The tank at Rankins Springs showing the general arrangement of the structure|
Then as suddenly as they started using this type of stand they returned to a steel stand and remained with the steel stand for the remainder of the tanks constructed.
Today only five of this type of structure remain – Tallimba and Rankins Springs (both on the Rankins Springs line), Yannagee (moved to Cooma in late 2001), Tumbarumba (jib removed) and Mole Creek Tank on the Dorrigo line. The structure at Megan, also on the Dorrigo Line is partially (mostly) dismantled. The foundations can still be found at Westby, Coolah and Yearinan
|Detail of the structure at Rankins Springs showing the bracing ties. 21 August 1998|
|Detail of the method of attaching the bearers to the joist on the Rankins Springs tank. 21 August 1998|
|The strap bolts that secure the bearers to the piers on the Rankins Springs tank. 21 August 1998|
|The tank at Rankins Springs showing the attached jib. 21 August 1998|
Lifting (American) Jibs
During the construction of the Batlow line in 1922-23 (it was opened on 17th December 1923) a new type of jib was used. The lifting jib was a copy of a type widely used in the United States for many years (hence their name) and it’s the origin of its use in New South Wales is not known. IT is suggested that it may be as a result of a visit by senior railway staff to the Americas and Europe in the early 1920’s or possibly seeing its use in Europe during the First World War – a large number of water column in Europe using this type.
Where as previous jib designs swung out from the tank the lifting jib simply lifted clear of the loading gauge with the train passing under it. The jib was made from No. 6 SWG Galvanised Iron and was thus significantly lighter than the swinging type. The support and lifting mechanism of the jib being more complicated though.
Two more lifting jibs were built in 1924 on the Dorrigo line and there was then a four year gap before the next example was constructed – during this four year period very few elevated tanks were constructed and this is the main reason for there being gap. Five more examples were constructed from late 1928 through to 1932 and with most tanks located in the country being provided with a lifting jib.
Lifting jibs were provided on the following tanks – the approximate construction date is also listed:
- Batlow (12.1923)
- Megan (11.1924)
- Dorrigo (11.1924)
- Bullenbung Creek (10.1928)
- Naradhan (1.1929)
- Casino (6.1930)
- Crooble (6.1932)
- Boggabilla (6.1932)
- Taralga (removed from Dubbo)
|The lifting jib at Naradhan showing the general arrangement of attachment to tank with a steel stand 21 August 1998|
|The spout, which was located on the end of the jib has fallen off from the jib at Naradhan. 21 August 1998|
New Panels and other Minor Changes
The panels that made up the tanks also underwent a change during this period. In 1917 following the passing of the Government Railways (Amendment) Act the previous year and as a result the passing of the responsibility of the new lines from the Public Works back to the Railways there was a move to bring the construction of components in-house.
The design of the panels remained the same although the scalloping on the outside changed slightly. The major change to the panels was that the casting became the responsibility of the PerWay Workshops in Newcastle. Each year the workshops would cast a number of panels and some of them would have a builders plate cast into the outside of the panels. This was the first time since the round tanks that there was an indication on the tank of who built them. A 20000 gallon tank required 60 square panels, 32 corner panels and 4 corner segments, the segments being the small sections at the bottom corners of the tank. 40000 gallon tanks required another total of 84 square panels. It is estimated that the workshops cast a minimum of 800 panels per year between 1917 and 1929.
|The builders plate on a panel of the tank at Naradhan 21 August 1998|
|The interior of the tank at Naradhan showing the interior webbing of each plate and the bracing style used on a single tier tank of the period. 21 August 1998.|
|The interior of the tank at Naradhan showing a section where two panels join. Iron filings were used to seal the two panels together to avoid leakage. 21 August 1998|