Stone Arch Viaduct / Bridge


3-D appearance

I believe this concrete 'curb' will mask the edge of the cork roadbed on the deck of the viaduct.

I also think I will try to make some sort of 3-d casting of those stone columns and glue those over the joints between images.

That might make things appear more 3-d overall?
(3-D columns: maybe just paper copy bend over and glued to partial round of wood/plastic dowel?)
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(3-D columns: maybe just paper copy bend over and glued to partial round of wood/plastic dowel?)
That might make the upper stone post a rigid affair that could support real wire handrails strung between them??

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Yesterday I was moving forward to add that upper connecting structure to my existing bridge,...only to find out that the existing one I have must have been built for a 2" C/L track spacing. Doubling that upper bracing structure would not work.
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I would instead have to modify the track spacing to 2.5" track spacing and construct a new double track version utilizing 2 new kits.

I resisted this notion until I discovered that I had already provided for a 2.5" C/L spacing for my 2 mainlines down at the bottom of the viaduct up ramp.
 
Here is the new bridge kit built,...now to fit it in.


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Note how you see thru the deck now,...no extra support piece required underneath
 
Now I want to thrown end another little curve ball idea. What if I made that bridge structure span one less arch structure,..like this
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When I was originally developing this combination of viaduct and then steel bridge span idea, I approached as though the viaduct was the original structure on this site,...ALL viaduct. Then industry and the future came along and needed a track passing under this viaduct,...one large enough to allow double stack container trains to pass under it. My steel bridge was going to have to replace some set number of full arches. The 18 inch span of that plastic bridge could replace 3 arch structures if the arch structures were 6" each,....thus my choice of 6" wide arch structures.


Now what if in this make-believe world the planners set their plans on a 3 span affair, and started construction on that steel structure,....BUT then decided that they really only needed to span 2 arches of the viaduct. Why couldn't that longer bridge be set down on the smaller cut out span in the stone arch structure??

Edited: Maybe I need to leave a little gap between the steel bridge bottom beams and the top of the stone arch structure (where it was 'shaved off') ?
 
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For now I have dropped the idea for that extra span of the stone arch under a portion of the steel bridge.


I went back to determining the exact segments I wanted to divide this viaduct up into,.... then reconfirming the exactness of the grade, ....then laying cork roadbed on it. The desire to divide it up into segments was two-fold; make it easier to handle on and off the layout,...and permit a portion(s) to be removed to get at that back corner in the future. So it shakes out like this:


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1) the segment that connects the viaduct to the back wall (tunnel to helix). It also contains the 'wye' turnout, and the branch off to the other portion of the viaduct. It will have full depth cork on the 2 tracks leading to the helix as that's the dimension I already cut that hole/tunnel. On its other leg leading to the single track portion of the viaduct, it will taper down to half that thickness cork roadbed.


2) the double track bridge itself that mounts into recesses at either end.


3) the top portion of the long run out that consist of stone arches. This portion's cork must taper down to zero cork height utilized on the final run out. This was a messy job, sanding that cork down to zero. Thank goodness i was able to do it outside on my work table.
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4) Then the final portion which will have a crossover set of turnouts mounted on its flat smooth surface.
 
Locating Pins/Dowels

Up till now I have had the paper pattern handy to locate the portions of the viaduct legs, but that is soon to be cut away. I wanted to have a 'repeatable way to position the portions of the viaduct. At first I thought of steel pins, but then said why not wood dowel pins. I only need a few at the end of each span, and they only need to stick up a little proud into the viaduct legs,..
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For the past several weeks I have been working on another portion of my layout, and I was fortunate to be able to work on that portion out on my carport work bench. We've had a real cold snap here in FL, so I decided to retreat into the warmth of my train shed and work on getting the tracks, turnouts, feeders, and segments of my stone arch viaduct sorted out.

I had mentioned before that I was dividing up my stone arch viaduct into 3 or more sections such that some sections could be moved out of the way to access spaces behind them. I was still unsure as to how I would be providing feeder wires to which sections, and where that would be specifically. I also needed to provide power to the solenoid on the Peco 'wye' switch up on the viaduct. Well I decided how I was going to do that, so now I needed to get busy laying that track across the bridge and into the tunnel leading to the helix,...should be pretty straight forward,...right??...not exactly !!

I believe I may have invented some new cuss words, or perhaps I just recalled some I had forgotten. At any rate I used quite a few.

One of the major problems is this opening in the back wall to the helix out back is about 40 inches across the deck from the edge of the aisle.
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I needed to get two non-kinked tracks into the 'wye' turnout and get that short piece of track to mate up with the derailer located in the tunnel. Then i needed to get that all soldered together,...lots of fun...NOT. Trying to get nice flowing curves into short pieces of flex track is not that much fun,..its not like bending longer pieces of flex track. I ended up having to eliminate the two isolation joiners on the frog rails of the Peco turnout,...they were just to flexible. I finally went with metal joiners to get some rigidity. Then I can get the track glued down into nice non-kinked joints. If the insulfrog Peco presents any shorting problems then I will dremel cut an insulation joint in there.

It was also a chore to get those joints of the 2 tracks soldered up in that tunnel entrance. Finally had to give up for the day before I tackle other problems in this corner.
 
Grade Transistion Dilemma

I am working on transitioning one side of my stone viaduct down to mainline track level,...and it is very close to a turnout on the mainline track,..
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The long Peco turnout belongs to one of the 2 mainlines, and is located right at the bottom of that fairly steep ramp at the end of the viaduct. As I was laying cork on the viaduct in preparation to lay track, I became very concerned about this grade transition,....was it too steep, was it too abrupt, was it too close to the turnout.
I went looking thru track design books this morning, then this discussion contribution by John Garaty,...
https://model-railroad-hobbyist.com/node/40366?page=0#comment-444064
I was getting ready for some pretty hefty discussions to work this thing out, particularly as I had in the past on my old layout (Central Midland) experienced considerable grief with 'dips' and 'prouds' in trackwork. I DID NOT want problems here as a considerable number of my trains will be using this ramp, both going up it, and running down it.
I started out trying to lay straight edges across very track sections of this transition zone, and it was going to be difficult to photo potential problem areas. I subsequently decide to just try and run some locos thru it and see what happened. I got out a selection of 6 axle diesels that I figured would have problems here. The first one was a CSX Spectrum that I often used to find trouble spots on my old layout. Its trucks are NOT articulated, and its wheel flanges are real small. NO PROBLEMS
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Okay lets try a recent acquisition, a Genesis FP45
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How about this selection,....and MTH NS, a Proto DL109, a std Athearn,...etc
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None of them experienced problems either climbing nor descending. I'm going to leave well enough alone for now, and move on with laying the track to the upper connection,...no radical transition there.
 
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