NSW Railways Infrastructure and Operations

Tuesday, 13 December 2011

Chakola Bridge

The southern most 'big' bridge on the Cooma - Bombala line is over the Numerella River at Chakola. Located at 415.658km it is one of the longer timber railway bridges in New South Wales. Among those that are longer are the Murumbidgee River bridges at Gundagai and Narrandera but not much else. Made up of 47 spans of various lengths the bridge totals 390.1 metres (1280 feet) in length. To HO scale that translates to 4.5metres or 14'8" in the old money - while long, the bridge is just doable to scale on (say) two 8 foot modules - but thats for another day.

The bridge is made up of (from the northern (or Up) end):

one 15 foot trestle span
21 x 26 foot trestle spans
5 x 42 foot Howe Trusses
19 x 26 foot trestle spans
one 15 foot trestle span

When constructed in 1889 the whole bridge was a ballast top type but by the 1960s the main spans were beginning to show their age and work was undertaken to convert the main spans to a transom top. In 1978 further work occured on the main spans when steel RSJ's were added underneath the main Howe trusses.

The bridge suffered 'flood damage' in 1989 which ultimately closed the line. While this was the 'excuse' that was used some weeks after it was 'closed' 5910/train/1210 ran over the bridge to join the 100 year celebrations of the opening of the line at Cooma.

With no maintenance since the late 1980s the bridge, at over 120 years old, is beginning to show it's age and at least one pier on the southern approach trestle has sunk and there are numberous holes in the ballast top apporach trestles. Usually the river runs so low you can actually walk across (at times without getting your feet wet) - time will tell but the next big flood to come down the Numerella River could wash away parts of the bridge.

The main Howe Truss spans from the Down side of the line -
note the steel RSJ's underneath.

A view along the main span from the Southern (Down) end.

Detail of the end of the ballast top trestle and the main spans at the
southern end.

More detail of the end of the Howe trusses. Note the marking
indicating the fatigue in the timber - these are all over the bridge

Detail of the truss of the southern most span

More detail showing the tension rods.

The inner end of one of the trusses.

A view of the end of the truss at the top.

The inner end of the truss showing how the ' handrails' are attached.

The ' handrails' between the Howe trusses - these are not load bearing.

Looking south from the main spans showing the section
of the southern approach span where one of the piers
has sunk

Looking north showing four of the five main spans.

Detail of the main spans showing the transom top conversion.

Another shot of the end of the truss.

Detail of the bottom of one of the trusses showing the tension rod.

The top of the truss showing the saddle for the tension rod.

Detail of the truss

Detail of the truss showing the transom top.

The southern approach trusses - note the 416km post.

The southern approach trusses looking north showing the 'sunk' piers.

Another shot of the sunk pier.


View of the end of the southern trestle and the start of the main trusses - the concrete base of the pier is a much later addition.

The underside of the main spans showing the additional RSJ's.

One of the piers of the main spans - note the adidtional
timber to support the RSJ's

The underside of the Howe Trusses.

The piers of the mian spans - note the additioanl timber to support the RSJ's

The top of the piers - and the addition RSJ supports.

Monday, 17 October 2011

Bredbo Bridge

Been a while since the last posting (been on holidays)..........

The line from Queanbeyan to Bombala still has a wealth of infrastructure that has not been removed by the razor gangs even though the line closed 25 years ago. The bonus is that the Cooma station and yard has everything that was there in 1965 (although the water tank is a ring-in relocated from Yannergee).
Among the items on the line are the three large timber trestles over Ingelara Creek, Bredbo River and Numerella River. All three are readily accessable if you are prepared to do a bit of walking (although check with the land owner first).
This post (there will be other posts on the infrastructure of this line) will concentrate on the 1889 built Bredbo River Bridge located at 412.616km, just under two kilometres south of Bredbo station. The bridge has ten 40 foot timber ballast topped Howe truss spans with brick abutments. Unique is the 30 degree skew of the timber piers, skewed to the flow of the river.
I have all the timber and bolts required to build an HO scale model of this bridge - stay tuned.

The bridge viewed from the down side looking in the down direction.

Along the bridge from the up end in the down direction.


Looking in the up direction - note the scouring of the ballast due to the failure of the timber decking in recent years.

A view looking down showing the only
major items of steel in the whole structure.

A view of two of the spans

Detail view of the span.

A view of the abutment from underneath - note the red lead
paint on the timbers - virtually everything the NSWGR did
in timber was painted with the red lead to protect it.

A side on detail view of one of the spans.

A view of one of the timber piers - they are much wider than
normal piers due to the skew - of interest is that the piers on
the original plan are brick (similar to the brick sections of the
piers of the Ingelara Creek bridge to the north).

A view from the downstream (or up side) of the bridge looking
in the down direction - the skewed piers can clearly be seen

A view showing the upper section of one of the spans.

The brick abutment.

A view underneath of the abutment.

Saturday, 13 August 2011

The American or Lifting Jib

During the construction of the Batlow line in 1922-23 (it was opened on 17 December 1923) a new type of jib was used on the tank at Batlow. This lifting jib was similar to the type widely used in the United States for many years (hence their name). While 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 a result of seeing its use in Europe during the First World War – a large number of water columns in Europe were of this type.

Whereas 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 but it was four years before the next example was constructed. There being no reason for this gap other than very few tanks were constructed in this period. Five more examples were subsequently constructed from late 1928 through to 1932, all of them in country New South Wales.

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 (moved from Dubbo)

There were two tanks constructed during this period where the type of jib (swinging or lifting) has not been able to be established. They are at Westby (constructed in 1925) and Ballina (constructed in 1930). Any information on these would be appreciated.

Todaythe tanks at Bullenbung Creek, Naradhan, Casino and Crooble survive although only Casino and Naradhan still have the lifting jib in place. The tank at Boggabilla was removed in the 1990s.

The 20,000 gallon tank at Naradhan showing the lifting jib.
By the time of this photo, 1998, the end of the jib had
fallen off and was lying on the ground.