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Viaduct roadbed and related questions

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  • Member since
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Viaduct roadbed and related questions
Posted by ROBERT BRABAND on Saturday, January 14, 2023 6:52 PM

I am creating a layout set in Pennsylvania, transition era. I've put together a nice stone viaduct from Metcalfe Models, UK. Fun build. But I've come up against several questions and the research I've done is at best ambiguous. I'm betting the knowledge I'm looking for is here in the forum.

1. Does track on a stone viaduct have cork roadbed or not? I’ve been searching for an appropriate photo of various viaducts scattered across Pennsylvania and other northeastern states but all I’ve found are photographs that show the viaduct from the ground level (to display the stone work) or from an elevated level (aircraft or drone) to display the length. Apparently showing what the tracks look like at track level is a “not-so-much” thing. I would assume cork roadbed, for it's sound-deadening quality, is preferred. But I wonder if that would raise the track too high above the deck.

2. Do tracks on such a stone viaduct have guard rails or rerailers like tracks that cross a truss bridge? I would assume so, but again the high elevation photographs I’ve found aren’t detailed enough to prove for me one way or the other. 

3. If viaducts like this use guard rails, where is the appropriate place to begin such rails - at the exact beginning of the viaduct where the transition from fill to viaduct takes place? Or - several feet or several ties before that transition? Photos in other threads here show both examples. There likely is no “standard” in the prototype, but what have you done?

4. A final question: I remember seeing an article in a magazine about bending the guard rails (a small nick cut into the inside foot of the rail) and soldering them together at the point but I cannot track it down. I also saw a Forum discussion here that noted the guard rails should NOT be joined at the ends, to prevent a short-circuit. Current (sorry, I could not resist - and that in and of itself is another pun-ish incidence) thoughts about that? A layer of thin styrene between the points was suggested, which makes sense, yes? Or leave the guardrail "point" open, unconnected, but each guard curved in toward the center? Your practice here?

5. And I was fortunate to have already purchased my ME bridge track along with the lighter gauge rail for the guards. Think I've heard people are having trouble finding it. Good to go. For the most part.

Robert

 

 

 

 

 

 

  • Member since
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  • From: Harrisburg, PA
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Posted by hbgatsf on Saturday, January 14, 2023 7:23 PM

I will give you a more detailed answer later. For now search google maps for the Rockville bridge north of Harrisburg and zoom in on satellite view. 

Rick

  • Member since
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  • From: Potomac Yard
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Posted by NittanyLion on Saturday, January 14, 2023 7:45 PM

Regarding each one:

#1 - Both.  Some stone viaducts have sides high enough that any roadbed profile is obscured or unnoticable because the ballast is going right up against stone taller than the roadbed.  Others, the Thomas Viaducted in Relay, MD for instance, have clear ballast profiles that cork on the subroadbed would represent.

#2 - The first three I went looking at (Thomas, Rockville, Starucca) did not have guard rails. Presumably, there's ones out there that do.  My general understanding is that guard rails are there to prevent derailed equipment from striking the bridge structure or lineside structures, not to keep the equipment from falling off the bridge entirely (which may be impossible?).  Given that the structure of the viaduct is entirely below the track, there's no superstructure for it to strike.  For instance, I know of a bridge that consists of a deck girder over water married to a "regular" girder over railroad tracks.  Only the girder bridge has guard rails and the deck section does not.

#3 - No standard I can see.  To me, it would depend on if the bridge is removable or not.  If the bridge is removable, I'd end the guard rails at the ends of the bridge.

#4 I would not leave the point open.  That just seems like an open invitation to snag something, like your skin.

  • Member since
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  • From: Collinwood, Ohio, USA
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Posted by gmpullman on Saturday, January 14, 2023 7:51 PM

I seem to recall most, if not all, the PRR stone viaducts having a ballast base and no guard rails.

 210317_6_barree by lmyers83, on Flickr

Or here:

 BIG VIADUCT by Scooter Hovanec, on Flickr

I've seen many of the PRR stone arches "bolstered" with the addition of steel channel to help keep the stonework aligned.

 Amtrak 04T Spruce Creek by Dustin Faust, on Flickr

If you decide to go the guardrail route this might be helpful:

 BandO_bridge_guardrail by Edmund, on Flickr

Although B&O the concept might be the same. I have seen some guardrail installations with cast steel "points" where the rails join.

Good Luck, Ed

  • Member since
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  • From: Harrisburg, PA
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Posted by hbgatsf on Sunday, January 15, 2023 6:47 AM

NittanyLion

My general understanding is that guard rails are there to prevent derailed equipment from striking the bridge structure or lineside structures, not to keep the equipment from falling off the bridge entirely (which may be impossible?).  

It happens.

Others have given good info.  I will add that the Rockville Bridge is a big railfan site and a search will turn up many photos.  BTW - I spend a lot of time there.

 

Rick

  • Member since
    August 2003
  • From: Collinwood, Ohio, USA
  • 16,220 posts
Posted by gmpullman on Sunday, January 15, 2023 7:06 AM

In 2010 some double-stacks were blown off the Rockville Viaduct. 

 Rockville Bridge Derailment by Spherical Harmony, on Flickr

Guard rails wouldn't have helped much.

 Rockville Bridge Derailment by Spherical Harmony, on Flickr

Cheers, Ed

  • Member since
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  • From: Potomac Yard
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Posted by NittanyLion on Sunday, January 15, 2023 9:01 AM

That's what I meant by impossible. The rail doesn't appear robust enough to keep equipment from going into the river in all cases. 

  • Member since
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  • From: Harrisburg, PA
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Posted by hbgatsf on Sunday, January 15, 2023 9:05 AM

NittanyLion

That's what I meant by impossible. The rail doesn't appear robust enough to keep equipment from going into the river in all cases. 

 

Ah, I thought you were saying that it was impossible for the cars to go off the bridge.

Rick

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Posted by PennsyLou on Sunday, January 15, 2023 11:02 AM

hbgatsf

 

 

 

Nice Smallie!!!

 

 

  • Member since
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Posted by ROBERT BRABAND on Sunday, January 15, 2023 2:04 PM

hbgatsf

 Others have given good info.  I will add that the Rockville Bridge is a big railfan site and a search will turn up many photos.  BTW - I spend a lot of time there.

 
NittanyLion

 

Others have given good info.  I will add that the Rockville Bridge is a big railfan site and a search will turn up many photos.  BTW - I spend a lot of time there.

 

I almost did as well. Long time ago I interviewed at a church in Gratz just up the road. Didn't go so well, think they really didn't want a "big city pastor" trying to adjust to small town life. Turned out in my favor though so.

Thanks for the viaduct help. I looked at Rockville and Starruca. I was surprised to see a turnout for a divergent route on the viaduct. Guess prototype railroads are more confident their track work is safer than our model track work. Or at least mine.

Robert

  • Member since
    February 2017
  • From: Harrisburg, PA
  • 635 posts
Posted by hbgatsf on Sunday, January 15, 2023 5:13 PM

PennsyLou

 

 
hbgatsf

 

 

 

 

 

Nice Smallie!!!

 

 

 

Thank, but that fish wasn't anything special for the Susquehanna. It was a little over 16" and 2.5 pounds. Wasn't even the biggest one of that day but I wanted a picture with the bridge in the background.  

Rick

  • Member since
    August 2014
  • 53 posts
Posted by ROBERT BRABAND on Tuesday, January 17, 2023 11:25 PM

Thank you gentlemen. I'm going with cork roadbed between the viaduct "floor" and the track, and no guard rails. Which makes it all easier. Anyone want to buy some n-scale ME bridge track?

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