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Quiet Roadbed

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Quiet Roadbed
Posted by GN goat kid on Saturday, December 14, 2019 11:06 PM

In the MR Special Issue How To Build Realistic Reliable Track (published in 2009) there was an article entitled "Quiet roadbed, better train sound" by Bob Kingsnorth. He did some wonderful experiment and concluded that "camper tape" under cork was the most effective sound attenuator. Has anyone done additional experimenting? And, last but not least, what is "camper tape?" Where can I get it? What form does it come in? How much does it cost?

Thank you,

The GN Goat Kid

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Posted by Overmod on Saturday, December 14, 2019 11:43 PM

GN goat kid
... what is "camper tape?"

It's usually closed-cell nitrile 'foam' tape with adhesive both sides.  Also known as 'topper tape', it's the stuff used to attach caps or the sides of slide-in campers to pickup truck beds.  

Wide range of sources online.

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Posted by GN goat kid on Saturday, December 14, 2019 11:58 PM

What widths does camper tape come in?

GN Goat Kid

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Posted by wvg_ca on Saturday, December 14, 2019 11:59 PM

You will also get a quieter track by using semi-flexible glues / adhesives rather than traditional rigid adhesives, like white glue ..

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Posted by SeeYou190 on Sunday, December 15, 2019 12:32 AM

If you are going to use closed cell foam tape, why ot go all-out and use 3M VHB tape? It would certainly hold a camper-top on!

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It is not hard to get, but you better never want to take it apart again.

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-Kevin

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Wink Happily modeling my STRATTON & GILLETTE RAILROAD. A Class A line located in a personal fantasy world of semi-plausible nonsense on Tuesday, August 3rd, 1954.

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Posted by gregc on Sunday, December 15, 2019 4:25 AM

i read that the major cause of noise is nails between the track and wood benchwork.   

greg - Philadelphia & Reading / Reading

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Posted by wvg_ca on Sunday, December 15, 2019 5:19 AM

I assembled my layout [15 feet by 16 feet] by gluing the track to foam [no underlay] glued to 3/8 plywood [Dap caulking] .. I also set the ballast [and ground foam] with a mix of Dap caulking, water, and alcohol ...

No rigid adhesives, no nails anywhere , it's actually rather quiet .. :)

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Posted by NVSRR on Sunday, December 15, 2019 7:58 AM

I use a floor underlayment called easy mat. And it is 3/16 thick, same as cork.   Has a peel and stick bAcking. And kills noise.   Which is what it is designed to do.   I handlay my track and it holds nails very well.    Per strip it is cheaper than per strip of cork.    Even quiets down pink foam.  

A pessimist sees a dark tunnel

An optimist sees the light at the end of the tunnel

A realist sees a frieght train

An engineer sees three idiots standing on the tracks stairing blankly in space

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Posted by GN goat kid on Sunday, December 15, 2019 9:44 AM
You bring up a very good point. I have been trying to find a flexible adhesive that will allow me to reposition the track in the future. Do you have any recommendations?
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Posted by selector on Sunday, December 15, 2019 1:38 PM

GN goat kid

... He did some wonderful experiment and concluded that "camper tape" under cork was the most effective sound attenuator...

The GN Goat Kid

 

I had the intention of using topper tap on my current build.  I abandoned it.  It was too sticky, too hard to shape curves without folding and distortions.  It's not intended for the purpose to which we want to put it.  It is meant to be laid straight, not curved.

I don't have a lofty experience to call on in the hobby, but what I have has taught me that cork is a truly excellent silencer.  So is foam.  The trouble isn't those two, even if used in combination for Tim the Tool Man's 'more power'.  The trouble is that, when we go to ballast, we impose a rigid shell over our silencing foam/cork and creat a sound box that is (enter figure relating to length of ballasted tracks on your layout) long.

If your goal is to have silent, barely clickety-click, running on your layout, you would need to first lay a thin cork sub-roadbed.  It should be wide enough to accommodate all your ballast, including double or triple mains wide.  Atop that you place your preferred roadbed, even plywood if you wish.  Apply tracks, ballast, and you'll have fairly quiet running.  But, if you use an adhesive, and then a topper or usual roadbed, which now has two densities of cancelling sound properties (dual density works best, which I can explain later if you wish), you'll undo it all with that hard shell of ballast over it that makes contact with the platform on which the roadbed rests.

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Posted by selector on Sunday, December 15, 2019 1:43 PM

GN goat kid
You bring up a very good point. I have been trying to find a flexible adhesive that will allow me to reposition the track in the future. Do you have any recommendations?
 

DAP Alex Plus with silicone.  The stuff that dries 'clear'.  It works far better than any of the 'coloured' ones, trust me.  The stuff that is labeled clear is actually white squeezed out of the tube, but it will dry clear, if very slightly yellow.  Most importantly, it is flexible and easily sliced through with an old butcher knife.

The trick, as always, whether using it to fix foam/cork into place, or the tracks they support, is to keep the amount to a minimum.  You lay a single thin-ish bead, along the length of roadbed, then smear it thin like paint.  That's all you need.

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Posted by Overmod on Sunday, December 15, 2019 2:51 PM

selector
I had the intention of using topper tape on my current build.  I abandoned it.  It was too sticky, too hard to shape curves without folding and distortions.  It's not intended for the purpose to which we want to put it.  It is meant to be laid straight, not curved.

You can't really bend it laterally whether it bends or not and preserve the point of using it.  You need to cut wedges or notches toward the inside radius, as in bending moldings, or cut and miter-bevel a series of straight pieces and abut them.  

Remember this is subgrade, and doesn't have to be smooth or continuous the way the cork roadbed overlay is.  Doesn't really have to be full side-to-side under the whole width of the bottom of the cork 'ballast prism' either, and could easily be tiled or pieced together under the paper track-layout templates.  Its purpose is only to attenuate any acoustic energy that makes it past the cork.

An additional question is how transition spiraling and superelevation was handled in this design: do you superelevate the camper tape layer, or just shim the cork on top?  I think the latter would be easier and better long-term.

Yes, you'd need an acoustic break between hard ballast and hard scenery.  We should take up what methods work and what methods don't.  Is there a reason something like clear silicone in a shaped bead with ballast sprinkled on and then Dullcoted wouldn't work well enough for this purpose?

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Posted by wdcrvr on Sunday, December 15, 2019 3:05 PM

I evidently read the same article at some point.  I used the camper tape (purchased from Rural King in their automotive/trailer department) as a subroadbed and then laid cork roadbed on top of that.  Did not really have problems with curves.  I have a minimum radius of 30" on my layout.  Plus you can cut the tape and apply in short lengths to avoid any kinking on curves.  Super quiet.

wdcrvr

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Posted by ATLANTIC CENTRAL on Sunday, December 15, 2019 3:22 PM

Still building layouts the old way......

3/4" plywood over 1x4 framing, or on suitable risers,  homasote or Homabed/Cascade roadbed.

Generally nail the roadbed down with brad nailer.

Glue the track with adhesive caulk, real adhesive caulk, not Alex plus, generally prefer clear PolySeamSeal.

Ballast with via several methods......

Superelevation between roadbed and ties.....

Trackage has always been solid and quiet. As someone who builds HiFi speakers, I think the real secret to quiet track is solid, none resonant benchwork.

Sheldon

    

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Posted by richhotrain on Sunday, December 15, 2019 4:08 PM

All of the HO scale layouts that I have built have been framed with 2x4 pine lumber and a 1/2" cabinet grade plywood layout surface. I nail my track down into the plywood surface.

While unballasted track laid directly on the plywood surface has been relatively quiet, there is even less noise when the track is laid on foam or cork roadbed. Add ballast to the track laid on roadbed, and the noise level increases. Glue down the ballast on track laid on roadbed, and the noise level increases more. At least those are my unscientific observations.

Rich

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Posted by ATLANTIC CENTRAL on Sunday, December 15, 2019 4:19 PM

richhotrain

All of the HO scale layouts that I have built have been framed with 2x4 pine lumber and a 1/2" cabinet grade plywood layout surface. I nail my track down into the plywood surface.

While unballasted track laid directly on the plywood surface has been relatively quiet, there is even less noise when the track is laid on foam or cork roadbed. Add ballast to the track laid on roadbed, and the noise level increases. Glue down the ballast on track laid on roadbed, and the noise level increases more. At least those are my unscientific observations.

Rich

 

Just my theory, cork and foam are too soft, they allow vibration. They dampen it until you ballast, then the ballast/glue becomes a speaker cone.

More rigid base means less virbration transmitted in the first place.

That's how we build speakers systems without virbrations we don't want.........heavier, more solid, not soft and spongy.........

Sheldon

 

    

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Posted by richhotrain on Sunday, December 15, 2019 5:05 PM

ATLANTIC CENTRAL
 
richhotrain

... At least those are my unscientific observations.

Rich 

Just my theory, cork and foam are too soft, they allow vibration. They dampen it until you ballast, then the ballast/glue becomes a speaker cone.

More rigid base means less virbration transmitted in the first place.

That's how we build speakers systems without virbrations we don't want.........heavier, more solid, not soft and spongy.........

Sheldon 

Well, as I say, those are my unscientific observations.

My theory is that the weight of a loco is so insignificant that the noise factor is hardly noticeable.

Rich

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Posted by Doughless on Sunday, December 15, 2019 6:38 PM

selector

 

 
GN goat kid

... He did some wonderful experiment and concluded that "camper tape" under cork was the most effective sound attenuator...

The GN Goat Kid

 

 

 

I had the intention of using topper tap on my current build.  I abandoned it.  It was too sticky, too hard to shape curves without folding and distortions.  It's not intended for the purpose to which we want to put it.  It is meant to be laid straight, not curved.

I don't have a lofty experience to call on in the hobby, but what I have has taught me that cork is a truly excellent silencer.  So is foam.  The trouble isn't those two, even if used in combination for Tim the Tool Man's 'more power'.  The trouble is that, when we go to ballast, we impose a rigid shell over our silencing foam/cork and creat a sound box that is (enter figure relating to length of ballasted tracks on your layout) long.

If your goal is to have silent, barely clickety-click, running on your layout, you would need to first lay a thin cork sub-roadbed.  It should be wide enough to accommodate all your ballast, including double or triple mains wide.  Atop that you place your preferred roadbed, even plywood if you wish.  Apply tracks, ballast, and you'll have fairly quiet running.  But, if you use an adhesive, and then a topper or usual roadbed, which now has two densities of cancelling sound properties (dual density works best, which I can explain later if you wish), you'll undo it all with that hard shell of ballast over it that makes contact with the platform on which the roadbed rests.

 

I have read where someone used waxed paper set next to each side of the affixed roadbed so that when he ballasted, there would be a small gap between the hardened ballast and the plywood subroadbed.  Since the diluted glue mixture would not stick to the waxed paper, after it dried, he simply pulled out the paper and the thin gap stopped any vibrations being transmitted to the plywood, which is the cause of the noise in the first place.  

Merely placing ground foam up next to the ballast hid any gap, which would hardly be seen anyway unless in photographs.

Seems like a reasonably easy thing to try.

- Douglas

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Posted by selector on Monday, December 16, 2019 11:48 AM

Overmod

 

 

 

You can't really bend it laterally whether it bends or not and preserve the point of using it.  You need to cut wedges or notches toward the inside radius, as in bending moldings, or cut and miter-bevel a series of straight pieces and abut them. 

Agreed, and that's where I lost interest.  I don't enjoy much about building layouts, believe it or not; they are a means to an end.  When they become too close to a chore, I back off or look for shortcuts.  My third layout had a cork-rubber sub flooring underlayment cut in strips, with all them little wedge-shaped gaps cut out of them so that I could lay it around curves.  Won't do that again any time soon. 

Overmod

Remember this is subgrade, and doesn't have to be smooth or continuous the way the cork roadbed overlay is.  Doesn't really have to be full side-to-side under the whole width of the bottom of the cork 'ballast prism' either, and could easily be tiled or pieced together under the paper track-layout templates.  Its purpose is only to attenuate any acoustic energy that makes it past the cork.

That was my expectation, and it worked rather well.  In fact, I had 5/8" plywood cut into sub-roadbed, and intended to have that 'dual density' factor imposed by the cork/rubber which became the roadbed.  The plywood was surprisingly quiet already.  Once it was all ballasted, I found it to be quite quiet.

Overmod

An additional question is how transition spiraling and superelevation was handled in this design: do you superelevate the camper tape layer, or just shim the cork on top?  I think the latter would be easier and better long-term.

I eyeball the spirals, and let the natural flex of the flex track elements determine the actual lie.  I'm usually pretty close, but you'd be correct if you anticipated that I would have to lay somewhat wide sub-roadbed and cork to account for variances. This is good because it also results in the confinement of the ballast to an upper layer, thus avoiding the soundbox problem with the hardened ballast coming into contact with the extruded foam base or plywood.

 

I do the super on curves with plastic packaging bits under the ties, maybe 1 mm thick. Again, I let the flex determine how it wants to get to the apex height and back down again, and once that seems reasonable, I use ballast under the ties to hold it as it should be.  Seems to work.  I make the odd mistake once I run trains over a curve, but it's easily corrected.

Overmod

Yes, you'd need an acoustic break between hard ballast and hard scenery.  We should take up what methods work and what methods don't.  Is there a reason something like clear silicone in a shaped bead with ballast sprinkled on and then Dullcoted wouldn't work well enough for this purpose?

It would probably work, but it sounds like it could be tricky to get it to look good...dunno.  Wider sub-roadbed, with properly scaled roadbed atop it, would reduce the chances of contact between the hardned ballast and what supports the sub-roadbed.

I learned as a budding astronomer with an 11" SCT on a heavy mount that a dual-density damper under the tripod legs served well to reduce vibration and oscillations. Waves is waves, so sound attenuation should work the same way...?  But, all the dual and treble density in the world won't work when there's an acoustic shell (the hardened ballast) resting it's lower and substantial hem on the base-structures.

 

 

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Posted by Overmod on Monday, December 16, 2019 12:51 PM

selector
But, all the dual and treble density in the world won't work when there's an acoustic shell (the hardened ballast) resting its lower and substantial hem on the base-structures.

Thanks, and much appreciated.

There's a product out for Christmas that boasts you can apply it to a wide range of items and surfaces to turn them into Bluetooth speakers.  Toy dump trucks, coffee tables, windowpanes ... "it's a speaker!"  (Carefully ensuring on the package there's no note about plus or minus 3db 50-15000Hz or whatever Wink

I promptly thought about something we did in college with a dorm neighbor prone to blasting loud music from time to time.  There was apparently a product called a 'wall driver' that would convert an area of sheetrock wall into a kind of flat-plate speaker 'cone' -- we decided that a reasonably large voice-coil linked to a stud or nail could, as my roommate picturesquely put it, 'turn the whole wall into a large defective woofer'.  For the purpose necessary, it performed almost astoundingly well.  But it soured me on any future tolerance of amplified running noise in model railroading via a similar effect...

 

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Posted by jjdamnit on Monday, December 16, 2019 1:18 PM

Hello All,

This from a previous thread...

"Hello All,

To adhere Woodland Senics foam roadbed to the blue foam base I use General Electric (GE) Clear Silicone I or II caulk.

The difference between the two formulae is curing time. The Clear II is "Rain Ready" in 30-minutes.

I use a 1-1/2-inch plastic putty knife to get an even thin coat of caulk on the roadbed before positioning it.

One advantage of using silicone caulk is it cleans up with water.

A disadvantage is some people don't like the odor of curing silicone caulk so for them this can be a "deal-breaker".

I too use "T" pins to hold the roadbed in place and allow it to cure for 24-hours.

Then I use #19 x 5/8-inch wire brads to hold the track in place while ballasting using the method outlined in this post...http://cs.trains.com/mrr/f/88/t/258968.aspx

If I do need to reposition the roadbed, it peels up easily and, using a rubbing motion, the caulk balls up and actually cleans the blue foam. 

If the track is ballasted I re-wet the ballast, pull up the track and then pull up the roadbed.

This method works for me. I have not tried it with cork roadbed and/or Homosote®.

I suspect because of the porousness of cork and or Homosote® the silicone caulk might soak in and cause damage when attempting to reposition."

Another post described using fiberglass home insulation, after the wiring has been completed, between the benchwork members to help deaden the noise of the trains.

Hope this helps.

"Uhh...I didn’t know it was 'impossible' I just made it work...sorry"

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Posted by Overmod on Monday, December 16, 2019 1:27 PM

jjdamnit
I suspect because of the porousness of cork and or Homasote® the silicone caulk might soak in and cause damage when attempting to reposition."

You need to use a sharp, thin knife, perhaps vibratory (I don't know if heat would help in trimming silicone), in the case of cork at least.  I'm not sure if the silicone impairs the sound-insulation quality of the cork by wicking into the voids, but it will assuredly pull particles or clumps out of the underside unless sliced, even if the pulling is drag from cutting.

It is possible to get around some of this by bonding the bottom of the cork 'irreversibly' to some sort of membrane, and then siliconeing that membrane to the subgrade.  This makes subsequent removal much more 'positive'.  You might have to carefully cut the membrane along the edge of the cork 'ballast prism' with something like the appropriate series of X-Acto blades if it is 'wider' and has become involved with ballasting or scenery in some way...

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Posted by rrinker on Monday, December 16, 2019 2:12 PM

 There's just no need for the silicon-ized stuff, really. Plain latex adhesive caulk is perfectly fine. I originally used the PolySeamSeal brand Sheldon mentioned, but mainly because it was like 10 cents a tube cheaper than the DAP. Considering I built an entire 8x12 double track layout, roadbed to abse and track to roadbed, and JUST cracked in to the second tube at the very end of tracklaying - it doesn't really matter. 10 cents won't even get me a cup of coffee. When I started my last layout, the local Lowes no longer had any PolySeamSeal products, so I ended up using DAP adhesive painter's caulk. No difference, really. Worked exactly the same way.

 In both cases, I has no issues removing track from the roadbed - in the first layout it was Woodland Scenics foam, in the last one it was cork. Short sections of cut flex I don;t usually consider worth saving, but turnouts are too expensive to just bust up and get new ones. Full or nearly full lengths of flex can be reused as well. On neither layotu did I have any issues getting the track up when I changed my mind and adjusted the plan a bit. This was before ballasting though. Both those layouts were built on extruded foam - getting the WS foam off the extruded foam was pretty futile, in some cases the foam roadbed stayed stuck to the foam base, in others, the top layer of the foam base came up with the roadbed. On the other layout, I used cork. Being somewhat tougher, the cork always came up - though sometimes it pulled bits of the extruded foam with it. On plywood - I doubt there would be any issue removing caulked down cork.

 They key to the track comign off undamaged it to use SMALL amounts of caulk. I was using the stuff that dries clear, but it comes out white. I spread it out so thin it basically makes the cork look shiny, mostly clear even before it dries. That's proven to be plenty to hold the track in place, even on curves, with Atlas flex, which likes to spring back straight when let go. If you have MRVP and watched the It's My Railroad Series, in the one where he lays some track - #8 or #7, not only does he use Liquid Nails which is going to set up hard, he also uses WAY too much, only botherign to clean up the one spot where it actually oozes out ABOVE the ties - in other areas you can see it well into the ties, just not up to the tops. It doesn;t take that much to hold the track in place - with that much adhesive applied, it WILL be tough to pull up the track undamaged at a later time.

                                       --Randy


Modeling the Reading Railroad in the 1950's

 

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Posted by Overmod on Tuesday, December 17, 2019 1:23 AM

rrinker
... getting the WS foam off the extruded foam was pretty futile, in some cases the foam roadbed stayed stuck to the foam base, in others, the top layer of the foam base came up with the roadbed.

It occurs to me that there will be a solvent that collapses the cellular structure of the foam base but not that of the Woodland Scenics product.  Even if there's slow attack, you should be able to collapse the adherent foam bits to a gel, wipe them off, and have reasonable 'flatness' for relaying, and then passivate the surface with something water-based that also preferentially 'carries' the solvent.

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Posted by rrinker on Tuesday, December 17, 2019 7:31 AM

 Some things just aren't worth the effort. I don't have limitless money to throw at hobbies, but it strikes me that trying to save every last little bit of a previous layout borders on insanity. $15-$20 turnouts - absolutely. a $2 piece of foam roadbed? And having to deal with a harsh solvent to do so? Just not worth it.

 Only thing I saved off my last layout was the electronics, I didn;t peel off any track or turnouts, I'm not going to be using the brand in my new layout, so no point in having it take up space. If the junk guy who carefully stacked the sections took it home and salvaged what he could, good for him. It still cost me less than what I would have paid to take it to the town dump myself, and I barely had to lift a finger - just point at what I wanted taken away. For less than the dump fee, him and his two helpers loaded it all in their truck, took what was truly junk to the dump, and did whatever to make extra money with the rest. Everybody wins.

                              --Randy


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Posted by riogrande5761 on Tuesday, December 17, 2019 11:32 AM

rrinker

 Some things just aren't worth the effort. I don't have limitless money to throw at hobbies, but it strikes me that trying to save every last little bit of a previous layout borders on insanity. $15-$20 turnouts - absolutely. a $2 piece of foam roadbed? And having to deal with a harsh solvent to do so? Just not worth it.

Only thing I saved off my last layout was the electronics, I didn't peel off any track or turnouts, I'm not going to be using the brand in my new layout, so no point in having it take up space.  ...

                              --Randy

 

That's my philosophy.  I did save what was practical off my old layout, which was a lot, including spikes, track nails, drywall screws, rail joiners, and almost all of the track, and even cork roadbed.  Anything that was fairly easy to recover.  That's the key, fairly easy.

My track wasn't fastened yet with any adhesive or ballast so it was pretty easty to recover, turnouts, same, all.  I decided to sell all my old Atlas turnouts and replace with Peco; the proceeds weren't a great deal but it did help.  I was able to fit ALL my flex track and turnouts into one long box that had been used to ship flex track to me.  The space it took to move it was pretty minimal (2nd photo)

Of course a layout in a more complete state would have probably yielded less saved items.

Rio Grande.  The Action Road  - Focus 1977-1983

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