Wednesday, 26 September 2018

Kyeamba Creek Bridge - 2

I really do not know where my time goes.   Progress on the bridge has been glacially slow on the modelling front,  partially because some indecision on my behalf on the best way to proceed,  although I have been able to continue with some rollingstock acquisitions, a brass loco repair, and more research. 

8 car RUB set hauled by 3825 leaves Wagga in 1962.  Photo taken and kindly provided by Tony McIlwain. The train is passing the upper quadrant signal, which we now believe was to protect the Edward Street level crossing.  No, this picture  has nothing to do with the Kyeamba Creek bridge, but this image and others, are some of the reasons why time ran short on the Kyeamba creek model   

Now that I had a dimensioned sketch, (see part 1) the first part was to locate a suitable piece of pine.  My desire was to include both bridges on a single section of timber plank. Whilst I did have some chipboard, and some 9mm thick ply, these materials were either too heavy, or too bendy.  Sure the ply could have been re-inforced, but a trip to Bunnings located a 1 metre or so long pine plank, with enough width to fit the bridge wing abutments.  The width is also in keeping with my future plans to minimize the width of the upper deck benchwork.

Solid pine was used for the subroadbed “causeway” between the two bridges.  This also assists with stiffening the pine plank.

The two bridge openings were marked on the plank, and the pine subroadbed was glued between the 2 bridges. 3mm MDF board (also obtained from Bunnings), was cut according to the sketch, shaped, and glued into position for the Kyeamba creek bridge.  Gaps were filled with Aldi brand filling compound 

The Kyeamba Creek bridge opening is around 50cm wide.  It didn't come out too well in the picture, but I have penciled in the location of the creek, and the timber piers.  The pine "causeway" subroadbed extends to the unnamed creek, and I have left enough space for this bridge too on the plank.  Distance between the two bridges is the compromise.  The concrete abutments are 3mm MDF.  This gives a thickness close to the 1 foot estimate of the prototype abutments.  Note too that most of the abutment will be buried in scenery

The unnamed creek will have traditional timber supports.    One thing that I assumed, was that the water level in the unnamed creek, and Kyeamba creek would be the same, as the railway is fairly level between these 2 creeks (confirmed by looking at the railway gradient diagram), however, the water level for the unnamed creek is higher than Kyeamba creek by at least a metre, which might look a bit odd on the model.  To get around this, the unnamed creek may be modelled as a dry stream
Next step was to attack the Ironbark trestle bridge that I recovered from an earlier layout.  The only thing wrong with the trestle, was that the timber piers were the wrong height, so needed to be removed.  The bridge deck though was perfect for reuse, so I didn’t want to damage it.

My original trestle bridge segments

My glue of choice back when I constructed the trestle, was white glue.  White glue is normally not waterproof, and I hoped that this was the type I had used.  Carefully, I applied water to the joint, and waited, applying some more water as soon as the first lot disappeared into the wood.  After around 5 minutes, the glue started to “go white” at the join, and with some careful pressure, the piers separated from the bridge deck. 

2 timber piers removed.  The plastic squeeze tube was ideal to get the water exactly where it was needed

All timber piers separated from the bridge deck.  Now the construction can start

Ironbark Models suggested and provided plans for a jig to make up your own timber trestle piers. 

Nest stage is to complete modelling the concrete abutments, and this will also set the rail height.  The subroadbed will then be built up to this height, prior to fitting the unnamed stream timber abutments.  Once the first one is in, then I will know the positioning for the other timber abutment.
Hopefully my next post will show a lot more progress.   Happy modelling.

1 comment:

  1. Hi Rob, the bridge is coming along nicely. An example of modifying the kit to suite a particular location is very useful.