# First attempt at a bridge.



## Manco (Jan 5, 2009)

So I needed a bridge for the over/under spot at my layout. After scratching my head for months trying to concieve of a way to scratch build a deck girder without having to weld anything, I gave up and went with option B, a warren truss.

I chose to make it out of PVC material as... alas, I have no welder and no welding skills. Not to mention PVC is cheap.

Today I fabricated a form for my abutments. As you can see, this finely crafted example was fabricated to be a precision concrete forming aparatus . The first abutment can be seen drying in the forms.










And the backside... only a mother could love this beast.










Also are some pictures of the warren truss bridge in rought form. It still needs to be painted, pedestrian walkway added, and diagonal bracing along the top. The top bracing will have to wait until the bridge is installed as my ladder roadbed is already in place and the bridge will have to be slipped in from underneath the track. The main structurals are PVC lattice edging and the bracing members are ripped PVC lattice strips. It's a 4' span.




















Hopefully tommorow I can strip the forms and pour the 2nd abutment and have the bridge installed on the layout soon. I'll update this thread as things progress.


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## tom h (Jan 2, 2008)

Nice bridge, I like the forms, that is how I have done mine in the past, find every scrap piece you have to make it work.

tom h


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## SE18 (Feb 21, 2008)

Nice, 

Where do you get flat PVC. My only experience with PVC is plumbing. 

Are you going to paint the abutment or rub cement over it and place it outside?


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## aceinspp (Jan 2, 2008)

Looking go so far. Looks like the abutments should do quite nicely. Later RJD


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## Manco (Jan 5, 2009)

I found the flat PVC at Lowes. Another semi-local chain of privately owned hardware stores carries it as well so I'm sure you could find it at either home depot or Manards or whatever large chain may be in your area. The strips are basically an individual strip of lattice that you see a large 4'x8' sheet of lattice work made out of. Why they sell it individually I'm not sure, I mean who really wants to build a web of lattice work one strip at a time? You'll find it in the moulding aisle where all other trim is sold. There's usually a small section of PVC or plastic trim. The edging is usually found wherever all the lattice work is sold. It's simply an edging and the strips slip snugly into the groove making it possible to form framework or, in this case, a bridge.

I took the abutment out of the forms thismorning. It's still too soft to safely handle though.


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## SE18 (Feb 21, 2008)

thanks; looking forward to seeing the abutment after you strike the mold & bridge in place


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## leftyfretguy (Jan 2, 2008)

I went to home depot and couldn't find the stuff you used but I could have been looking at it and not realized it. What does the material look like in its original form? How much does that bridge weigh? 
very cool! thanks for posting, 
Matt


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## Manco (Jan 5, 2009)

The material in it's original form looks just like it does in the photos, only in 8' strips. The main structurals are basically just a channel. The channel is the same width as the lattice strips themselves. Like I said above, they'll probably be found in different areas of the store. The channel is where you buy sheets of lattice work. The lattice strips will be in the moulding and trim isle.


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## MasonsDad (Feb 7, 2008)

Now that looks nice for the first one, i really like the Abutments, they should both look great when your done


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## sldozier (Apr 5, 2009)

Very nice bridge! I'll be checking out my neighbor Lowes today for that flat pvc channel material and if they have it, that's my next project! 4 foot span? Trying to detrmine the dimensions of the pieces based on the picture. Is the bottom structural the 4 foot piece or the top? How far apart are your bottom cross beams?


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## Steve Stockham (Jan 2, 2008)

Hey, not bad! Not bad at all!! I'm looking forward to the pics of the finished project.


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## smcgill (Jan 2, 2008)

Now that's a great idea!!!








Do you think a 6' bridge would be to much?
What glue are you using?
What were you using for plans?
Sean


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## Manco (Jan 5, 2009)

Yes, a 6' bridge would be too much without an intermediate span support. I'm having doubts this 4' length would keep from bowing over time if you were to rely on the structure itself to support trains. As it was, I was going to run my ladder roadbed right through the bridge, making it look like a girder section, which would have added to the structural integrity of the bridge. I'm not using glue, I tried to at first but it simply wasn't working. I used sections of the thinner lattice strips in the corners with screws fastened through them... sort of like an internal gusset would be the best way to explain it.


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## smcgill (Jan 2, 2008)

Did you try using the pipe glue from the plumbing are? 
What glue did you try? 
Once you put it all together tell us if it got any stronger. 
Sean


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## Manco (Jan 5, 2009)

I tried using a plastic adhesive that came in a caulk tube. Not sure exactly what it was. I didn't try using PVC plumbing glue. I think with the minimal amount of surface that comes into contact between the peices, that I'd rather have the strength of a mechanical joint rather than relying on adhesive. It definitely gets stronger the further you assemble it. The intermediate pieces that form the "lattice" work of the bridge are actually screwed to the perimeter pieces of the bridge once again creating a mechanical connection.


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## Trains (Jan 2, 2008)

I made a couple of stations out of PVC and pipe glue works good, make sure you use the cleaner first.


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## John J (Dec 29, 2007)

Where do you get PVC in Sheets? 

How thick are the sheets? 

I did my Bridge abutments using forms like you did

Only I poured them in place.


This is interesting.


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## Trains (Jan 2, 2008)

John J,

I get mine at Home Depot and Menard's, its white pvc house trim. They have all kinds of shapes.

Don


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## Manco (Jan 5, 2009)

I was wondering the same about the sheets of PVC. At Lowe's, the largest piece you could get would be a 1x6 so basically 5 1/2" wide. We just now had a Menards move into town so hopefully they'll have a better selection. I've always thought building structures out of PVC would be a good way to go.


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## smcgill (Jan 2, 2008)

O.K. Manco
How did the bridge come out?
When I went to Lowe's they have a glue made by the same manufactor as the u shape trim piece.
I did bye some, and it did glue the u shape .
I have ret to try it on the other type of plastic.
So how strong did it get when all was put to gether?








Sean


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## Manco (Jan 5, 2009)

It's not that strong. I can apply downward pressure in the middle of the span and get noticeable flex. It's definitely not strong enough for a human to stand or sit on as I've seen with the steel bridges. As I said, my ladder roadbed was going to stay intact over the bridge (representing a typical girder you might see on top of a bridge like this) which would carry most of the weight of the trains rather than relying on the bridge to carry the load. I do think the bridge could handle the weight of an average train though, but I definitely wouldn't try spanning over 4' without support.

I wish I could show you a finished product but it's basically only partially painted right now. #1 the weather turned too cold to spray paint & #2 my railroad is about to go undergo a huge revamping this spring so I'm not in a hurry to install the bridge because I'd have to take it right back out. Don't worry, I'll get you pictures hopefully this summer when it's finally in place.


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