# Triple track curved bridge: N scale



## videobruce (Jun 15, 2011)

I need to build two bridges on a curve that are triple track. Track is Peco code 55 flex. I plan on just spreading ballast over the plastic base of the spans, no cork roadbed.

One is short, around 6" in length, not a huge problem. The other is 16" in length that will have a offset center support. I plan on using 1/8" black ABS plastic for a base and custom extended length sections of Peco truss girder bridge sides (NB-38) for the upper support. Not any prize winner, it surely won't make the cover of MR. 

Attached are photos of the two bridges from the side and aerial shots with the longer span with track in place. The trusses you see have _*not*_ been lengthened. Nothing is attached or secured, just placed there for a overall idea what it would look like. That curved turnout is a approximate location on the short span. I'm also think since I have ample of vertical clearance of adding I beams or some type of narrow channel below. Also, that white center support will be changed due to lack of side clearance. It was a piece of 3/8" ply scrap left over from the table.

One question; _*will running traffic over a plastic base as what I plan be noisy w/o any cork roadbed?*_

Questions? Suggestions?


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## Big Ed (Jun 16, 2009)

How much noise can they make on that short stretch?
But I would say it will generate more noise without the cork, the cork will reduce the noise level. 

Can you compensate somehow and add the cord to what you have showing?


Coming along nice, looks like it will be a busy RR when you get all the track down.:thumbsup:


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## videobruce (Jun 15, 2011)

> How much noise can they make on that short stretch?


I can't imagine really any at all on the short span, but maybe some on the longer span.
The thickness of the base is the same thickness as the cork roadbed. I thought about cutting down the foam at each end to allow cork above the bridge, but since the height is the same, I was hoping to let to go as is.

I was mostly concerned about the appearance since it is somewhat lacking.


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## Big Ed (Jun 16, 2009)

videobruce said:


> I can't imagine really any at all on the short span, but maybe some on the longer span.
> The thickness of the base is the same thickness as the cork roadbed. I thought about cutting down the foam at each end to allow cork above the bridge, but since the height is the same, I was hoping to let to go as is.
> 
> I was mostly concerned about the appearance since it is somewhat lacking.


Well then, you said it above, Cut it down into the foam and add the cork it can't hurt for noise reduction and that way the bed will all look the same all the way around.

Is that 6 mainlines on the bottom level?

Did you test run anything yet?
I guess you don't have the power hooked up yet.


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## videobruce (Jun 15, 2011)

No, two on the left is the mainline, the four on the right are the receiving/departure yard. I did plan on five, but reduced it back down to four.

No on testing, nothing even close to being wired other than feeders to/from each piece of flex track.


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## Carl (Feb 19, 2012)

You will get a slight increase in noise, but nothing to really worry about.


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## shaygetz (Sep 23, 2007)

It looks like it's high enough for a ballasted deck plate girder bridge...not as showy, but easier to put in, soundproof and a more common type...

http://www.arema.org/publications/pgre/Practical_Guide/PGChapter8.pdf


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## videobruce (Jun 15, 2011)

Ok on the short span, but I think it's too long of a span for the longer bridge.

I just remembered that I had two single track Atlas high truss bridges I couldn't use left over from my 1st layout 15+ years ago. I have already cut them apart, separating the sides from the base and top. They are long enough. All I will need is something for the top cross supports.


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## videobruce (Jun 15, 2011)

To be clear, on those short sections of side trusses, they would not be the full length. I would 'kit bask' them longer.

Ok, how about this. From a Atlas single track truss bridge. The pieces are just 'sitting' there, they would have to be cut down in length.
Though, I don't know what to do about the top cross supports.


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## videobruce (Jun 15, 2011)

Here are the dimensions of that 'base' for the span. Vertical clearance is 2 3/8" as it is now (not to scale).
Clearance is 2 3/8" if I use the 3/32" black ABS sitting on top of the rigid foamboard as I originally planned. 
I now cut an additional piece of 3/16" Plexi clear, since I thought it would be a better base (you won't really see either afterwards). If I use the 3/16", it will drop the clearance accordingly since I will have to lower it due to the thickness of the roadbed.


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## videobruce (Jun 15, 2011)

Ok, here is what I hope is the finished product. I used CV HO scale plate girders (per recommendation), trimmed to length. I also bought some of their trusses for the offset middle support on the longer bridge.

I plan on getting those stone plastic 'panels' (assuming I can find what I like) for the 'walls' of the abutments to attach to the foamboard under each side of the spans. The clearance is somewhat excessive, as I seem to have a bad habit of going overboard on clearance as I did on my first layout. I decided to use 3/16" clear Plexi instead of that black, thinner ABS plastic for strength, but mostly so I could attach those plates to the side of the base. I also added strips of ABS that I cut for additional surface area to glue along the inside of the bridge for those plates. Those will be covered with ballast.
I also sliced the foamboard so the surface of the bridge base is level with the rest of the layouts foamboard and will use cork roadbed across the spans covered with ballast so no one will see the clear Plexi.


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## JPIII (Jun 24, 2012)

One of my favorite fishin' holes is right under a BN mainline bridge. That makes enough racket to wake the dead. Nothin' as great as a wildneress experience, eh?


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## videobruce (Jun 15, 2011)

And what does that have to do with anything other than nothing?


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## JPIII (Jun 24, 2012)

"One question; will running traffic over a plastic base as what I plan be noisy w/o any cork roadbed?"


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## videobruce (Jun 15, 2011)

It would of been nice if you quoted that question from 11 posts up so I knew what you were talking about.


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## Carl (Feb 19, 2012)

I think you have a workable plan.


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## videobruce (Jun 15, 2011)

But does it look ok?


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## videobruce (Jun 15, 2011)

I finally laid 95% of my track and I'm in the wiring stage.
Here are some pics of the bridges with the tracks laid (no scenery of course)


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## tjcruiser (Jan 10, 2010)

You've got quite the footage of track there, huh? Bridges look nice, so far. Gonna look even better with eventual landscaping / scenery. Keep us posted!

TJ


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## sstlaure (Oct 12, 2010)

Looking great. Any pics of the overall layout?


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## BK R (Dec 8, 2012)

The "new" bridges look spot on, the trestle ones didn't look right. :thumbsup:


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## Big Ed (Jun 16, 2009)

It looks strange with just one set of girders under it? 
Maybe add another set 2 tracks over on the right?


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