Wednesday 6 November 2019

Thomson River Bridge - 1

A smile for the camera moment. An excursion train on its way to Walhalla
Even though the plans were in effect unreadable I was able to determine the final bridge would be around 2 metres long in O scale. As I was slowly building my way out from Eden with baseboards as I went, I was able to allocate a length along the long wall of the shed for the Thomson River bridge build. I knew there was no hurry at this stage to devote modelling time as to how and when it would be built, that would come when I was ready.

So the easiest solution was to build a module for the bridge and then carry on past that section and build more of the layout.
Plan showing relationship of the bridge and Broadwater and Pambula modules.
Broadwater was the module prior to the track turning 90 degrees and then running across the bridge. When stepping up scales from HO to O scale it is surprising how quickly the 'real estate' disappears. When the trains get bigger the available space for them to run is quickly reduced. But if I was to go down to N scale (been there, done that) the available space would appear huge. So after adjusting to the space available the bridge module was connected to the Broadwater module.
As shown in the diagram I made a temporary track oround the alignment the final track was to go. This meant I would be able to carry out operation on the rest of the layout before I got back to the bridge build.
Obviously I had to make the bottom of this baseboard considerably lower to allow for the high concrete piers of the bridge. Having based my bridge on the real bridge I will also have to allow the sloping sides on either side of the river. There are many further things to research yet such as how do I do running water? I guess I will be busy watching the various Youtube videos on this topic. That will also include some practice goes as I wouldn't want the bridge to be looking good and then have crappy water underneath. I have done some water modelling in the past but not on this scale. Another obvious choice will be to model the river during a dry spell where there will be minimum water underneath to model. I have photos showing the water lapping all four concrete piers during heavy rain periods. But my choice will be to have lots of gravel patches under it, easier to model.
Ideal modelling scenario, more gravel, less water.
Obviously a rainy time the Thomson River is flowing

So the two photos clearly outline how different modelling this scene can be and I think my choice of less water will be easier to do. It is also interesting to see how different the foilage, river banks etc have changed over the years. It is going to be hard to model the tall timbers on the left bank but that is quite a while on.
Long timber shows bridge alignment
View from other direction
Temporary track to allow layout operation
This bridge build has been in the planning stage for a few years now. There are many facets that need to come together for the finished product. How do I make the piers? They look so complicated with their multiple faces. How do I make the trusses and the adjoining girders? What size timbers do I need and can I get stripwood to a similar size?
What I have to declare early on with this build is that I don't consider myself a great modeller. Where I might be able to get away with scenery okay, making an item that has specific measurements is another ball game. I must have said a few times over the life of the blog that I cannot cut a straight line, even with a mitre box! So in the end this bridge build will be a compromise and will hopefully be recognisable as a model of the Thomson River bridge.
As the Beatles song was "I get by with a little help from my friends" the next blog I will show how this bridge has become a team project.