The Halls Creek Bridge 2 - A Thank You

Following my earlier post on the topic, Ian Phemister  (http://iansmuswellbrookmerriwa.blogspot.com.au/) kindly provided me with a copy of his photos on the same subject taken from his extensive collection of information on the Merriwa line. It is a goldmine of detail. The first thing I noticed was that the shorter of the timber pier sets only has three piers rather than the four that I had constructed (based on old standard drawings). This has now been corrected. 

From Ian's information, it is also interesting to note that an extra pier set has been added to reduce the span between the larger timber pier set and the abutment. I presume this occurred sometime after 1970 as it certainly not there in a 1970 photo of 3090 taken on the bridge.

Many thanks Ian. Your assistance is greatly appreciated.

To start the fabrication of the components, I fixed a length of track upside down to a strip of ply and then glued the steel and timber beams to the underside of the track. The main concrete piers were shaped from styrofoam, coated a mix of coloured tile grout and 50/50 PVA/water, and weathered further with soft pastels and isocol alcohol. Looking at the photo below, I may need to revisit the right hand pier to lighten it up somewhat.

The concrete piers were then glued to underside of the steel beams, and then a further strip of ply was glued to the underside of the piers thus creating a plywood sandwich. Additional styrofoam was added to create the locations for the abutments and timber pier sets. Again, looking at the photo (still a work in progress), a bit of shimming is still required to remove the slight curvature that can be seen around both bridge abutments.

Once the basic alignment has been finalised, the terrain will be finalised, and then I can focus on the detail of the abutments and the underside of the bridge using the information Ian provided.

The Halls Creek Bridge

Photo from Merriwa Rail Society website - Photographer Unknown

After removing the non-prototypical and very distinctive brick viaduct, I still would like to have at least one reasonably sized bridge on the layout. Over the last few months, I have been searching the internet for possible prototypes and came across the bridge over Halls Creek at Sandy Hollow on the now disused Merriwa branch line. Interestingly, Google Maps (a very definitive source??) names the watercourse at the crossing point as Giants Creek but all of the literature that I have found refer to it as Halls Creek.

Photo from Merriwa Rail Society website - Photographer Brian Leedham

According to the Byways of Steam article on the Merriwa line (Byways of Steam 10 p62), this bridge was one of three on the branch line and the only one no longer in service. It is also the most basic but perhaps, the most interesting of the three with a combination of steel and timber superstructure and a mixed arrangement of piers. The other great attraction for this bridge is that a gentleman by the name of Brian Leedham took some photos of the main span which was still in place in 2009 and these have also been published in the Merriwa Railway Society's website (http://www.merriwarailwaysocietyinc.org/alongtheline.htm). The photos have been a great help in determining the arrangement of the main beams and the internal bracing for these. They also give an idea of the arrangement of the timber bearers on the shorter spans.

My intent is not to create an exact copy but use the bridge as a guide. Unfortunately I have not been able to locate any drawings for the bridge, and therefore, the dimensions that I am using to create the model are approximate based on comparisons with locomotives and rolling stock shown in several older photos of the bridge.

To date, I have fabricated the major span steel bream arrangement from styrene and the timber piles from bamboo satay sticks and stripwood from Northeastern Lumber. I have also added bolt heads from Tichy Train Products on the timber pier sets but drew the line at adding rivet heads to plate web girders. I have also cheated a little by not including all of the internal vertical cross bracing and the horizontal cross bracing attached to the bottom flange.

Once the individual components bridge are painted, I'll probably finish the bridge upside down, fixing everything to a length of track before placing it in position. 

The bridge when completed will not form part of the main layout but will be shown as a cameo scene on the branch line before it enters a helix that will provide access to the upper level.

More to follow as the project develops.