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.

1 comment:

  1. Hi there. Great photos, thanks. How do you get to the actual bridge? Can you cycle/drive close to it or is it a walk? I'm heading down that way soon and would love to take a close look. Thanks, appreciate your time. Trevor.

    ReplyDelete