GIRDER BRIDGE

OVER MUDDY WATER

Incorporating Micro-Trains'
girder bridge into a small module

 
 

This project was part of a "proof of concept" module built in 2014 which is not currently a part of my layout.

 
"The topic of model scenery construction is vast and dynamic". That's not my own statement, it's actually George Riley's, whose easy scenery tips and techniques are featured on the website of Railroad Model Craftsman magazine. And whilst it may sound like a truism at first (of course it's vast, given that there are so many different types of scenery through which the railways of this world run) I think what Riley actually has in mind is the fact that model railroaders usually start out with "flat layouts" before attempting to incorporate less linear terrain. Bridges are an example of a scenic feature which require a "scenic gap" in terrain if they are to make any sense, and Micro Trains' Z Scale girder bridge (which has been produced in various guises over the years) is great to get started in this type of scenery building.
 
The basic foundation of the "gap" had been laid down during the baseboard woodworking in what must be the most basic way possible: the approximate shape had simply been cut out of the plywood roadbed with a jigsaw and then fixed to the module framework, acting as ground level.

For the slopes, I used a modelling mass which is sold in a powdery form and then mixed with water - pretty much like papier mache, except the mixture I used contains wood fibres rather than just cellulose, resulting in a much thicker and ultimately sculptable mass which allowed me to build up the slopes without using (as I normally would have done) styrofoam shapes covered with plaster of paris.

According to the instructions the mass should have been dry after 48 hours, but I left it untouched for a week before giving it a liberal and overall coating of olive green acrylic paint. This extended to the baseboard top, all of which received a first primary colour base other than the pre-marked "footprint" of the double track, as I had drawn out guiding lines in order to ensure that the trackwork would be laid straight.

While very few of this will actually be visible on the finished layout, this step does take a "raw" layout baseboard a big step forward in terms of appearance.

 

 
 

  "Dynamic" can also mean learning from previous mistakes. When I built my first Z scale layout I incorporated a small lake - and the mistake was to think that pouring the resin was the truly decisive point when in fact this is just the finishing touch. The far more important part is to colour the bed of any water feature with different colour hues, giving it all visual depth by working with darker shades in the center and adding lighter colours toards the margins.

Depicting a generic Central Florida location, I was thinking more of an inland body of more or less standing water rather than a flowing stream. This has an important effect on the colours to be used, as stagnant water accumulates more organic matter and therefore appears greener.

The fact that the waterway I was adding to the module would be rather shallow also meant that the mudbed would be visible, requiring brown colours. The end effect (painted on with various dark green and medium to light brown glossy acrylic paints in several layers) provides the rather murky setting aimed for.

This is not a part of the countryside where many people would want to venture down to that particular stretch of waterway, not the least because of the potential wildlife dangers, so I opted to go for slopes heavily covered in vegetation basically undisturbed by human activities.

Attempting to depict this by adding a basic ground cover which also stands up a bit and gives the impression of a certain volume of vegetation, I used Woodland Scenics light green (FC145) and dark green (FC147) bushes, glued directly to the slopes.

 
They are marketed as being for any scale, depicting bushes, shrubs and tree foliage, but they obviously look like somewhat more substantial vegetation in Z scale. Still, I felt I pretty much got the effect I wanted.
 
With both slopes covered in vegetation, adding the water effect was next. This is traditionally achieved by pouring clear resin which then dries to form a flat and glossy surface which also has the "mirror effect" of water.

Based on availability at a local hobby shop I had bought a two component resin manufactured by Noch of Germany. Mixing the two gooey liquids (one of which is a hardening agent) 1:1 results in a clear resin which is runny to start with but then turns into a consistency comparable to honey before drying completely. This is great if you want to work ripples etc. into flowing water, but for this project I ultimately found that a simpler (and cheaper) single component resin would have been quite sufficient.

The mixing of two components also turned out to be a potentially messy affair, which prompted me to go for a done-in-one layer of resin rather than mix up several thinner layers (as every expert will tell you to). This caused a few more air bubbles than usual but they were mostly removed by brushing them out while the resin was still liquid, and the few remaining ones ultimately started to look like organic matter in the water, so I left them that way on purpose.

After about 45 minutes the resin started to set, taking on a nicely even watery surface effect. Some of the ground cover at the bottom of the slopes soaked up some resin, giving it a "wet" look which won't do for this location, but easily covered up with a little bit of "dry" foliage.

 

 
With the basic scenicking of the waterway and slopes in place, the baseboard of this module was ready for track laying.
 
Designed so it could be traversed by a piece of 110mm track, the two 83' bridges with pre-installed track from Micro-Trains (990 40 950) were assembled with their girders facing downwards rather than in their intended form as through-girders, and this required a 45 degree cut on the ends of both sides in order to accomodate the slopes.

This made the bridge "drop in" perfectly; no abutments were installed as they are taken to be completely overgrown by the vegetation.

There is also no need for any support from a stability point of view as the ends of tracks running across the bridge (made from plastic and therefore having very little own weight) are an integral part of the moulding and rest level on the subroadbed.

 

 
 
 

 
 


(c) 2014-2018

All images unless noted are (c) Adrian Wymann

 

page created 6 August 2014
last updated 27 September 2018