First go at a bridge

Handsomerob

Handsomerob

Catching the fever
So here is my first attempt at a bridge, it has a few more bits to add but it will span a section of the pond.

I've posted this picture in my other thread as well, sorry for repeating myself.

Does anyone have any suggestions or warnings about building bridges as such?

Here is the inspiration for this particular build.
http://www.jordoncooper.com/2014/08/cpr-train-bridge-at-east-coulee-alberta/
 

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OK, it's worth remembering that G scale bridges have to do a bit of work, in that they do have to support some weight - unlike the smaller gauges.

While the model is a typical Warren girder truss, resolution by triangle of forces will reveal that some of the members are in tension - therefore the connection points between the vertical members and the top and bottom horizontal members is pretty important.

The other thing that Korm points out is to connect the two girders across the top, at generous intervals - 4 connecting points should do it. This is because a single girder on its own could buckle, but by connecting across the top, you have formed a box, which is much stronger.

I did one (slightly shorter) in aluminium - sections intended for greenhouses :nod::nod:

002.JPG
 
Apart from connecting at the top, I added strength to the bottom by using deeper strips of wood and a few more cross pieces. As you can see it has a fair span and has been outside for a year or two!
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Can I suggest some gussets? the full size one would have had them and they add a nice bit of detail

Here's one I built earlier.................
bridge.jpg
 
Handsomerob said:
WOW! That's quite the engineering feat! how did you make your gussets?
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Rob,if thats a first attempt cant wait for the second,GREAT looking structure but agree with Minirains,some metalwork would really set it off.I would be interested too on how he made the gussets as a similar bridge is in the pipeline for my railroad in the future.
 
minimans said:
I confess I didn't make them! they came as part of the kit, I say kit it was a box of sticks.............but they are simple thin alloy sheet with rivet detail done with a punch. Check out the thread a bridge too far for more detail. https://www.gscalecentral.net/threads/a-bridge-too-far-or-long.231978/
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I just read your thread on your build. It's a shame you didn't get to use your bridge after all that work. My little bridge started life as an eight foot long spruce 2x4. and with a little Pythagorean theorem and some Trigonometry I was able to come up with all the angles and decided to go with 1/2 inch beam width. Yeah I'm in Canada but I like to work in the Imperial system when I do wood working.

I do in fact have all the fancy wood working tools, planer, jointer, biscuit joiner, miter saw, band saw, table saw, etc. However this bridge was hastily built on the Table saw, I hurt my back at work and am unable to do much right now so accessing the fancier tools isn't possible right now. (They say it's not the tools, but what you can do with the tools that matters)

I will be looking at designing a trestle system later on as I believe I will need to elevate my track up over some rock that we just can't "blast" out of the way. (aka: I need to add some visual interest on the long back straight)

Thanks for the support, and once I get the all clear on my back I will be back at laying my line and posting in my other thread.

I will look into maybe making some gussets. I do have some sheet steel from the race car kicking around.

Keep watching for gusset updates.
 
trammayo said:
Apart from connecting at the top, I added strength to the bottom by using deeper strips of wood and a few more cross pieces. As you can see it has a fair span and has been outside for a year or two!
View attachment 224419
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This is a great bridge, I like the visual interest, what type of wood did you use and did you treat it with anything? What are your winters like? I'm in Northern Ontario Canada, we get about 4 feet of snow on average so I'm worried about my bridges lasting the winters.

Did you model this bridge off of a real bridge or is this from your minds eye?
 
Handsomerob said:
This is a great bridge, I like the visual interest, what type of wood did you use and did you treat it with anything? What are your winters like? I'm in Northern Ontario Canada, we get about 4 feet of snow on average so I'm worried about my bridges lasting the winters.

Did you model this bridge off of a real bridge or is this from your minds eye?
Click to expand...

Apart from the two pieces of deeper timber and the two straights on top (cut from 3x2 red deal), all the rest is pallet wood of unknown source. I just painted it and nailed it together with 18g nails (air nailer). The ultimate intention was to construct one out metal as I did not think it would last this long (I think ten years so far!).

Wimters are (relatively) mild - usually plenty of rain and wind - although I have recorded minus 27 Celcius! Not a lot of snow either - but we still like to complain! I would have expected the nails to have rusted away by now.

The bridge is loosely based on the Connel Ferry Bridge in Scotland.
Here's a Wiki link; https://en.wikipedia.org/wiki/Connel_Bridge
 
Yep, this is why you need gussets - ignore the 'impact' bit, I think that was taking things a wee bit further.

3b74bdb862d27d0b0506872b1af81a32.jpg
 
Hi,

My Howe Truss is built from some rigid foam plastic, underneath it, to provide some strength are a couple of square section steel tube.

bridge 002 (Medium).jpg The sides of the 4 foot long bridge

complete 002 (Medium) (Medium).jpg The complete bridge, which as it crosses a garden path is removable. The compression rods are made from bicycle spokes.

Yours Peter.
 
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The bridge has at one end a small trestle, made from some pieces of a red cedar greenhouse, that was beginning to show its age (at 30 years). Red Cedar is virtually impossible to buy at a reasonable price here in the UK, so the source of it was very useful!

Here are 3 photos of the pair

como leaving the brige (Medium).jpg


xinglhside1 (Medium).jpg

The bridge over the access path, the tops of the trestle bents have RGS stle metal covers - made from the 4 thous thick aluminium that 'drinks' cans are made from the 4 thou thick aluminium sheets as rain protection.

t & b 005 (Medium).jpg

A close-up of the bridge - the fixing nuts and bolts on the sides, are the apparent ends of the bicycle spoke rods, and made from styrene and glued over the holes for the rods

Yours Peter
 
well, if everybody is showing off his bridge here, i'll join in.
cheap, easy and quick were the recommended features.

bruecke1-11.JPG



the building was described here: http://kormsen.info/bridges/ (scroll down nearly three quarter)

as it is indoors, the only stress it has to stand are visitors, who are longer than 5' 8" ...
 
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