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1:48 Scale Bailey Bridge Diorama


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This project started with the discovery and purchase of a couple of 1:48 scale Bailey Bridge kits on eBay. As a civil engineer and modeller I could not pass this up. The kits arrived and I built one span (a triple single for those in the know). A tricky kit to put together but worth the effort as it looks the part once completed.

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What to do with this bridge. It would look pretty silly on its own on a shelf - its a bridge and so needs to span something - a river or other obstacle.

So I had this idea of building a diorama. I have been building 1:8 scale armour for a few years and had a few Desert campaign vehicles completed so I decided to set in the Western Desert of North Africa circa 1942-43. The bridge would cross a dry river bed (wadi), which would have the added advantage of not having to model water (no flash floods for me).

So I got to work with some bits of timber and hardboard that I had knocking around and built a base. I also built a central pier with the bits left over from the kit and a second kit. This will be a two span bridge - a third kit is now needed to complete the second span. Back on eBay...

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:cheers:/>

Darius

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Once the base and sides were complete, I built up the landscape using bits of styrofoam packing from old electrical good boxes stored in the loft. The styrofoam was cut roughly to shape with a kitchen knife and glued into place with PVA. This is a model railway scenery technique and works very well. Once the glue had dries further carving and shaping was done as required.

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The completed styrofoam landscape was then coated with plaster of Paris (dental plaster) kinda sculpted to shape.

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The sides were then cleaned up and sprayed satin black and the landscape given a base coat of desert sand colour. This is not the final treatment as I intend to add various tones of flocks, desert scrub/shrubbery and the road/tracks as well as scattered rocks etc., which will be a learning process for me as I have never built something like this before.

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One one side of the diorama there is to be a 40mm Bofors gun emplacement with a sandbag wall surround. There are few 1:478 scale sandbag walls around and those that do exist are too small and very expensive - I think real sandbags are cheaper. The internet came to the rescue and on an armour forum the use of modelling clay was recommended. The technique is very simple and a lot of fun. All that time playing with plasticene 40+ years ago was not wasted!!!

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Really a special idea to make a model bridge to the main part! The bridge really looks good, why always doing vehicles and planes??

Haa...why not putting a prop fighter in the scenery just underflying the bridge? :rolleyes:

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Started adding the "desertscape" to one end today using various hues and sizes of gravel, plus some scraps of hemp as the small scrubby bushes that are common to the Western Desert.

Also painted the sandbags.

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:cheers:/>

Darius

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Darius,

Wow - nice landscaping! The bridge is going to look great in that setting - as said above it'll be hard to tell what the center piece is - especially if you put some armour crossing the bridge.

Respect man, :cheers:/>

David

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Looking good, Darius 70.gif !

Question: Will the bridge be the focal point?

I'm guessing that whatever you feel is missing maybe something that would/should draw attention to the bridge.

The pics you posted of the tanks on the bridge; the tanks looks like the focal point.

Just a thought; something to chew on.

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Looking good, Darius 70.gif !

Question: Will the bridge be the focal point?

I'm guessing that whatever you feel is missing maybe something that would/should draw attention to the bridge.

The pics you posted of the tanks on the bridge; the tanks looks like the focal point.

Just a thought; something to chew on.

I have been reading Shep Paine's excellent "Dioramas" book so I think I have an idea of what you are getting at.

The bridge is the large thing in the centre of the diorama so I guess that is the centrepiece. I am still playing around with the composition with respect to vehicles and figures etc. so there is no one focal point as yet. In a relatively close up shot of a tank, the tank will inevitably look like the focal point. I could leave the diorama free of vehicles and figures, which would leave only the bridge to "focus" upon but, to me, that would be a bit boring.

I have seen photos of model railway layouts with impressive large span bridges and the photos inevitably have a train crossing the bridge. As a civil engineer I tend to focus on the model of the bridge first and the train second. For others the focal point might be the train and the bridge is what draws their attention to it. I suppose the focal point is in the eye of the beholder.

:cheers:

Darius

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I have been reading Shep Paine's excellent "Dioramas" book so I think I have an idea of what you are getting at.

The bridge is the large thing in the centre of the diorama so I guess that is the centrepiece. I am still playing around with the composition with respect to vehicles and figures etc. so there is no one focal point as yet. In a relatively close up shot of a tank, the tank will inevitably look like the focal point. I could leave the diorama free of vehicles and figures, which would leave only the bridge to "focus" upon but, to me, that would be a bit boring.

I have seen photos of model railway layouts with impressive large span bridges and the photos inevitably have a train crossing the bridge. As a civil engineer I tend to focus on the model of the bridge first and the train second. For others the focal point might be the train and the bridge is what draws their attention to it. I suppose the focal point is in the eye of the beholder.

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Darius

Ah; That's exactly where I learned about dioramas!

What I was thinking about was something along the lines of having soldiers either working on the bridge or inspecting the bridge while the tanks and vehicles sit at the entrance to the bridge.

Depending on how comfortable you are with positioning and painting figures; Any figures in the diorama that's looking at or toward the bridge will greatly enhance the storytelling.

A Lee tank crew looking at the bridge with one pointing at it is a good example. Some engineer soldiers repelled over the side of the bridge looking at something is another. Maybe a couple of soldiers on the bridge straining looking over the side at the bridge structure. You get the idea.

By doing that with the figures and having the tanks and vehicles on the side(s) of the diorama, The observer/audience will quickly pick up and understand the diorama story.

BTW; These are just some examples off the top of my head at how to draw the audience's attention. Having a bridge as a focal point can be tricky because it almost always plays just a supporting role in a diorama so it has to really be obvious or jump out at the audience.

Looking forward to the rest of the progress!

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Interesting ideas. I am new to figure painting but am keen to have a go and apply the "stop sign" principle as explained in the book. I would like to see the bridge in use so perhaps there could be an Army Film Unit detachment on one side filming the tanks crossing. Also many bridges were given names with signs saying "London Bridge" so there could be a squaddie completing the painting of the sign...

:cheers:/>

Darius

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Interesting ideas. I am new to figure painting but am keen to have a go and apply the "stop sign" principle as explained in the book. I would like to see the bridge in use so perhaps there could be an Army Film Unit detachment on one side filming the tanks crossing. Also many bridges were given names with signs saying "London Bridge" so there could be a squaddie completing the painting of the sign...

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Darius

Whoa; That's an awesome idea!

Have a big reel-to-reel on a tripod or something similar.

That's a good point about bridges being named. It'll be interesting what you come up with.

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Part of an Army Film & Photographic Unit (AFPU) crew has been prepared over the past few days. I scratch built the camera/tripod installation and modified 28mm 8th Army figures for the AFPU personnel. The Chevrolet CMP is an ASAM Models white metal kit.

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To follow will be the painting of the bridge name sign bay a third AFPU member using a still camera. Plus the Bofors crew leaning on the sandbags looking at the bridge.

:cheers:/>

Darius

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Just an observation, but from an engineering perspective, I wouldn't think that bridge would support 2 tanks on any one span at a time. I'd say you're one tank heavy.

Look online at tanks crossing bridges, and you'll see that the spacing is usually quite wide. Like this:

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This gives a good indication why:

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Just an observation, but from an engineering perspective, I wouldn't think that bridge would support 2 tanks on any one span at a time. I'd say you're one tank heavy.

Hi Kozlok,

The load carrying capacity of a Bailey Bridge (or any other bridge) will depend upon its span and its type of construction. With respect to the military use of a bridge, each military vehicle will have a Military Load Class (MLC), which is a function of its weight, width, speed of crossing etc.

Bailey Bridges, being constructed from a kit of parts, can be built in different configurations depending on the span to be crossed and the weight to be carried. The spans can be one, two or three trusses wide on each side of the road deck and up to three truss "storeys" high - ranging from a single single (one truss on each side of the deck) to a triple triple (three trusses wide and high on each side of the deck). Sir Donald Coleman Bailey was a very clever chap.

Each Bailey Bridge span on my diorama spans 327mm between bearing centre lines. This scales up to a full scale span of 15.696 metres or 51.5 feet.

The M3 Lee/Grant tank has a weight of 30 short tons (27 tonnes), which gives it an MLC of 40.

I wanted my bridge to have a decent load carrying capacity so I built it as a triple single - three trusses on each side of the deck by one "storey" high. The triple single has an MLC of 40 (36.3t) for a span of 110 feet and an MLC of 70 (63.6t) for a span of 70 feet. The worst case bending moment is with the load at mid-span and calculations indicate a bending moment capacity of around 3000kNm (26,550 kip.in) for a triple single in each of those conditions.

My span is 51.5 feet. To give the same bending moment the maximum mid span load would be 78 tonnes - thus the spans in my diorama could carry two M3 tanks at mid-span and still be within the maximum bending moment.

Of course there are other issues, such as shear forces, SF and BM influence lines, and individual buckling of members, but these are accounted for in the MLC.

I am therefore confident in the load carrying capacity of my model Bailey Bridge.

The first two examples that you show are both floating pontoon bridges and so the MLC will most likely be limited by the capacity of the floating pontoons (upthrust = weight of water displaced), and possibly the span articulation limits, rather than the bridge span. They are also not Bailey Bridges so I cannot comment on their specific load capacities.

Your third example is a Bailey Bridge (Triple Single) and is a cautionary tale of what happens when you don't observe the MLC.

Great to be able to talk Civil, or rather Military, Engineering on ARC!!!

:cheers:/>

Darius

PS - I am a Civil Engineer by profession, as you may have gathered from the above...

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