# Arched, Curved Bridges



## irondan (Jan 7, 2008)

Ok … Lately we have been working on some very interesting projects. This one is definitely on the top of that list. We had our friend Howard from Atlanta come up to us with a challenge. He is building a new layout in his basement it is a basic oval shaped layout but the bridges that he wanted weren’t so simple… 










He wanted to have something like this bridge:




















Ok, an arched bridge takes some time to make but it is not very hard to do… now ... what happens when you want to have an arched bridge like that on a 180 degree curve at one of the ends of the oval and another arched bridge 90 degrees on the other end? 





















To be continued...


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## altterrain (Jan 2, 2008)

Dang. That will certainly be a challenge! 

-Brian


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## Torby (Jan 2, 2008)

This, I gotta see.


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## Westcott (Feb 17, 2009)

Not wishing to be anything but positive, but won't that curve put the bridge's centre of gravity outside its supports?


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## Steve Stockham (Jan 2, 2008)

Short answer: yes.


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## armorsmith (Jun 1, 2008)

Didn't Escher build one of those???  

Bob C.


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## aceinspp (Jan 2, 2008)

Well from what I've seen come across the MLS site nothing impossible and you folks never cease to amaze me. So on with the project and keep us posted. Later RJD


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## Totalwrecker (Feb 26, 2009)

All canter no lever... 

Of Course we want pictures! 

John


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## SE18 (Feb 21, 2008)

I don't know of any steel arch bridges like the one you pictured that are curved. The expense and engineering would likely be high. But maybe I'm wrong. 

Of course, it would probably look beautiful if you built it on your railroad.


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## coyote97 (Apr 5, 2009)

"great challenge" is the right expression.

Its a big deal to do this that in the end it gets a good look. Wish you all luck for that!
Thats a big project and it needs to have good result in the end.

Me, i wouldnt dare it.
Prototypical, all main structures are going from point-to-point in a straight way.
There are a handfull of bridges where the deck is a bit curved inside this straight structure.

Modern concrete Bridges often have a slight curve, but the balancepoint needs to be straight far inside the abutments or piles. Bridges with less stress are known to have the one or other curve, too (pedestrian bridges e.g.)

Even arched concrete Bridges or masonry often have straight structures inside ONE arch:

http://www.hotzesworld.de/FLO/BA-Alpen/Szenen+Motive/Landwasser-Viadukt-4-klein.jpg


So, im curious to see the ready product. If this works nicely: hat up ! 
Anyway: you make bridges fine enough that i have no doubt it will succeed. Good Luck!!

Frank


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## Pete Thornton (Jan 2, 2008)

There are a handfull of bridges where the deck is a bit curved inside this straight structure 
Frank said it - the prototype uses a series of straight bridges placed at an angle to each other. You can lay whatever track you want on top. 

So an Arched bridge probably can't be curved - each section would have to be straight and that would ruin the strength of the arch.


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## Stan Cedarleaf (Jan 2, 2008)

That certainly is challenge, Dan. But........... With the techniques you use and talent you and the guys in the shop have, I would say it's more than doable.


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## Semper Vaporo (Jan 2, 2008)

Do a google search for "Curved Bridges"... lots of fascinating info.


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## SE18 (Feb 21, 2008)

I searched and found dozens of pictures all over the world and found that a few are curved but only on the ramps leading up or down from the span section. If there are more than one set of spans, the curve is between them. I have yet to come across a curved span section. 

I did find some nice curved mortar or concrete arch bridges of a different type.


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## Semper Vaporo (Jan 2, 2008)

As for curving the arch... consider a cable suspension span... How would you get a cable to curve in two directions? Gravity is what creates the vertical curve... what would create the horizontal curve? An inverted arch (steel girder) is just an arch upsidedown. Gravity would pull the outside of the arch down and this would cause a sag on the outside of the curve... granted, throw enough steel at it and the sag might be controllable, but at a considerable cost in steel!


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## smcgill (Jan 2, 2008)

Robin Quick to the Bat Computer?


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## Semper Vaporo (Jan 2, 2008)

He can't come right now; He's in the batroom.


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## armorsmith (Jun 1, 2008)

From an engineering standpoint, I would say that "For enough time and money, anything is possible." 

However, from a practical standpoint, what is depicted in the early part of this post is very improbable. For the 'eye catch' effect, go ahead and 'imagineer' one. 

Bob C.


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## rpc7271 (Jan 2, 2008)

Technically, that bridge is impossible to build in real life. In G scale the materials we use are about 1,000,000,000,000 x stronger than we need so it is possible to build it. To have abutments that support it is another matter. It is going to want to tip over at the center unless there is a huge amount of weight at the abutments. You would be better off to make it a 2 span bridge and put a pier in the center.


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## noelw (Jan 2, 2008)

*Neat Idea.. Not Feasible in real life, but can be in our scale ........Yup ...it can be done.. Question is I'm a little confused on the grade tho... You showing 68 inchss to the floor at the Bridge abutments and 64 inchs to the floor back down aways before it straightens out.. 
Question... That 4 inch drop you show in a short distance with that grade can cause problems with couplers and cars... Need to know the dia. of the bridge before it straightens out and we can go from there.. Going to be odd but interesting.. 
It can be done by going to a scrap metal co. that can cut out the curve you want out of a pc of 1/4 inch plate steel and about 4 inch wide. Heat it up for the grade you need. It would set on the abutments and then around where you straighten out. Use some 3/8 all thread that can be bolted to a floor plate that can be the adj. for the bridge grade. Really not hard to do. Then bolt on 3/8 inch plywood on top of the plate steel and cut with a band saw to how wide and the curve you want for your dbl tracks and clearance for the stringers.. The plywood section can be 1 or 2 foot pc. or longer if you can bend it for the grades...I built a swing bridge and both Girders going to the bridge were on curves and had to have adjusters on both Girder ends before the bridge to align. Mine is a litttle over a 35 foot Dia. and has a 1.5 grade with the bridge in the middle of the grade.. 
If need be, give me the calcs and I'll draw it out for you and you can build the arch and stringer up from there. Noel *


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## noelw (Jan 2, 2008)

*I just notice the celling hangers so you won't need my idea for self supporting.. Still a neat bridge and very interesting to see it done.. *


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## SE18 (Feb 21, 2008)

I think we scared off Irondad. I like his idea and just b/c it wasn't built doesn't mean you shouldn't. I think it would be pretty neat myself.


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## noelw (Jan 2, 2008)

*Even Eaglewing on the head of this fourms could of fig. this one out easy.. Yup.......Would of been a interesting bridge and like to seen it done to.. *


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## SteveC (Jan 2, 2008)

Just give him a bit of time and he'll be back with some in process pictures and then some final completion ones.


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## denray (Jan 5, 2008)

I have built a couple arched steel bridges on a curve, my arches are underneath the roadbed. The one Dan is refering to will be a little more complicated, but what the heck, IT IS DAN, and Dan can do it. When Dan and I get together at these shows, our discussions go to some of the steel fabricating extremes. We are bouncing ideas back and forth all the time at the show. Thats what happens when you get two OLD steel fabricators together, that thinks alike. I am sure Dan will have the pictures soon of the finished project. Dennis


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## irondan (Jan 7, 2008)

Hello fellas,
I see that we got your engineer brains going. I'm glad that most of you already realized that this is G Scale and the ceiling is the limit or sky whatever applies. It might not be realistic but it shouldn't be a big deal for grown men playing with trains right? The main thing is to have fun with this stuff. 
As you figured ... something that I forgot to mention is that the outer track has a different elevation as it goes into the curve and then levels out on the straight sections. 
Anyhow, how about some pictures of the progress. 


We started by making the track base










Next in order to make the arches we welded upright braces to hold the curve of the arches in the right place



















After that, the truss worked started. Horizontal and vertical pieces were placed, little by little to keep everything aligned.


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## noelw (Jan 2, 2008)

*Looking good.. Keep posting more photos... *


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## benny2.0 (Jan 12, 2010)

LOL, Now thats nice.


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## smcgill (Jan 2, 2008)

Dan's the Man!!!


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## SE18 (Feb 21, 2008)

Posted By SteveC on 29 Jan 2010 11:38 AM 
Just give him a bit of time and he'll be back with some in process pictures and then some final completion ones. 









Ha! You're right! And what a treat too!


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## Stan Cedarleaf (Jan 2, 2008)

Unbelieveable..... That's an engineering and construction marvel.









Just about as complex as the Hoover Dam bridge. Well, almost....









Fabulous, Dan.


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## afinegan (Jan 2, 2008)

wow! Functioning(hopefully hehe) Metalworking artwork!


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## irondan (Jan 7, 2008)

A few more pictures. 









































That is all I have so far, now we have to wait for Howard to show us pictures of the installation, and some pictures with trains running thru those bridges


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## Totalwrecker (Feb 26, 2009)

Wow !!! Dan that is a work of Art! 
However the pic looking lengthwise reminded me of The San Francisco Earthquake! 

Another Great Job Done! 

John


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## Nicholas Savatgy (Dec 17, 2008)

Boy the UPS guy is going to be pissed after delivering all that......


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## tom h (Jan 2, 2008)

LOL , Nick that is a good one!!!









That sure is going to make his day!

tom h


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## denray (Jan 5, 2008)

Wow Dan I bet the OLD head hurt figuring that one out,







Great job, What would be cool now is when that gets installed, take some real looking photos and convince people it is a full size bridge.







Again great job.
Dennis


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## dieseldude (Apr 21, 2009)

I'm gonna need a bigger shop


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## Madman (Jan 5, 2008)

Beautiful work







, but a structural engineer's nightmare


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## Torby (Jan 2, 2008)

So how did you figure out that compound curve for the arches?


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## TonyLou (Sep 3, 2009)

Hi, Dan 
Great job ! This is very beautiful bridge. Thank you very much for sharing your super construction  
Tony


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## irondan (Jan 7, 2008)

Howdy Folks
We originally posted about this bridge back on June of last year. 

About two weeks ago we finally got some pictures of the installation of the bridges. 

Check this place...





















I can't wait to see some trains running on this layout. 















































Hopefully we get some more pictures soon


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## flats (Jun 30, 2008)

Great job on the bridge, and I can't wait to see some trains running either. 
\ 
Ken owner of K&K the road to nowhere


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## Nicholas Savatgy (Dec 17, 2008)

Now that's a Man cave.................









Great work Dan.


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## denray (Jan 5, 2008)

Wow Dan 
That looks fantastic, a curved bridge to cap off the end of the layout, I commend the owner to dream up the idea, and then the idea is only an idea without Dan the Man. 
Great job Dan 
Dennis


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## SE18 (Feb 21, 2008)

That is a serious sick bridge! Great job! 

And that train "museum" is an envy 

Dave V


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## Grimm (Oct 5, 2009)

Very cool. I have seen a real railroad bridge that was curved like that. Although it is on the Nevada test site and was the result of atomic bomb.  It was interesting though because when you first approach the bridge it looks normal, until you drive under it and that is when you see that it is curved but still on the pylons. No trains run or probably ever have run across it, as it was built for the above ground nuclear testing.


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## NTCGRR (Jan 2, 2008)

I'm sad when I see trains behind glass and not running....so sad!!!!!


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## smcgill (Jan 2, 2008)

Posted By NTCGRR on 02 Mar 2011 05:59 PM 
I'm sad when I see trains behind glass and not running....so sad!!!!! 
That's the next ( new, never been run) "colection " for sale!!
Sean


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## John J (Dec 29, 2007)

Posted By NTCGRR on 02 Mar 2011 05:59 PM 
I'm sad when I see trains behind glass and not running....so sad!!!!! 

Think of how the trains must feel


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## NTCGRR (Jan 2, 2008)

OH, YA !!!! Dan, the bridge is nice to.....LOL 

I was just over come with emotion....


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## John J (Dec 29, 2007)

What is this bridge made from? Wood, Plastic, or metal" a Will the blue strips from the bridge to the cieling be removed at some time? 

JJ


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## NTCGRR (Jan 2, 2008)

JJ steel, I think the blue is tape holding the plastic while they spray the paint on it.


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## jake3404 (Dec 3, 2010)

Your partially right, those blue "rods" are blue painters tape over the metal rods attached to the ceiling. Only way this bridge can stay up. I think he mentioned that earlier in this thread.


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## John J (Dec 29, 2007)

Posted By jake3404 on 03 Mar 2011 04:13 PM 
Your partially right, those blue "rods" are blue painters tape over the metal rods attached to the ceiling. Only way this bridge can stay up. I think he mentioned that earlier in this thread. 

Oh Cloud Hooks. I remember those when I was a kid.

I thought they were outlawed by the enviormentalist. They messed up the jet stream.


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## TURBOTOY (Mar 7, 2011)

Guys, check out the 12 foot arch bridge the guy has on ebay.


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