Ballasting/sound reduction

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Deltech
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Ballasting/sound reduction

Postby Deltech » Wed Apr 14, 2021 2:46 am

New layout planned.

Never ballasted before.

Been reading a lot about ballasting nullifying the sound reduction benefits of using cork underlay, and wondered if it would be possible to use the “rubber crumb” they use on artificial football pitches for combined ballast/noise reduction?

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Bufferstop
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Re: Ballasting/sound reduction

Postby Bufferstop » Wed Apr 14, 2021 3:13 pm

I don't think that rubber crumb would help, the noise increase is down to the PVA used forming a rigid bond between sleeper and sub base. To hold rubber crumb in place it would encapsulate the crumbs so that you would end up with a lighter solid ballast. I might be wrong but it's not an easy one to put to the test.
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Bigmet
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Re: Ballasting/sound reduction

Postby Bigmet » Wed Apr 14, 2021 5:26 pm

There are two key aids to noise reduction from model railway 'baseboards'.

First, reduce the surface area of baseboard on which the track is mounted. Don't use a large rectangular piece, cut it up into shaped lengths to take the track layout only. (Less material is required so there's a cost saving benefit, at the price of more constructional work.) Why this works: reduced efficiency of the coupling to the airmass of the vibration from the moving trains.

Mount scenic treatment independently from the track as far as possible. (Refer to 'open frame' layout construction to fully exploit this.)

Secondly, use an adhesive which remains flexible to bond the choice of ballast to the track and base. Copydex works well on stone ballast. Looks like a nightmare applied diluted in water, but just wait until it fully goes off before ripping your hair out! A small test section first to prove that it will end up looking good is a confidence builder. Why this works: the flexible adhesive absorbs some of the vibrational energy from the trains reducing what reaches the baseboard.

A compliant and flexible track base, and the rubber crumb ballast you propose, won't suffer nearly as much of the nullifying rigidity which the application of PVA will produce. But will Copydex be effective enough to bond the rubber crumb? I don't know, and a question of the manufacturer or supplier for their guidance would be a good place to start. Do let us know if you make a trial of this.

Deltech
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Joined: Wed Feb 17, 2021 12:52 pm

Re: Ballasting/sound reduction

Postby Deltech » Wed Apr 14, 2021 11:51 pm

Thanks for replies.

It'll be a “round-the-loft” circuit, of about 26’ x 14’. Each of the long sides have “up to” 4’ available width, but I won’t actually have 4’ worth of “stuff” on either side.

Like a numpty I WAS going to lay full 8’ x 4’ boards, but I’m now going to cut the boards into “strips”.

I’ll only need it wide enough for 4-tracks at “sea level”, so I reckon that’ll fit onto a 12” strip?

The “high level” circuit is only 2-tracks, so I can use a narrower “strip” than the low level.

I’ll use a wider board for the main Station (possibly 3 islands for 6 through platforms, plus 2 x “middle roads”).

At one “end” of the circuit there will be a freight yard, and at the other end there will be a TMD (accessed from the high level circuit). As the freight yard and TMD will have the high level and low level tracks next to them respectively, I suppose I can keep them on their own “strips” isolated from the main tracks?

The high level tracks will be set back nearer the roof/walls than the low level, so I suppose any scenic stuff can be mounted on its own “strips”?

====================================================

Which is the better underlay out of cork or foam? (and why?)

Bigmet
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Re: Ballasting/sound reduction

Postby Bigmet » Thu Apr 15, 2021 9:10 am

All to say there is that cork will last the life of the layout, even if that is decades. Synthetic foams may last the life of the layout, and are potentially degraded by solvents commonly used in railway modelling, so need to be tested with these before use,

Bigmet
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Re: Ballasting/sound reduction

Postby Bigmet » Thu Apr 15, 2021 11:50 am

Deltech wrote:...I’ll only need it wide enough for 4-tracks at “sea level”, so I reckon that’ll fit onto a 12” strip?...

This needed more discussion, so I left it for when I returned from the supermarket run!

If you use a flexitrack system (such as Peco Streamline) to build your layout - and you should in the space you have available! more to come on that - then the track width is 50mm, so four parallel tracks easily fit on an 8"/200mm strip. That's the simplest way for non-scenic lines.

But then there's realism. If you want the layout's scenic sections to look more realistic, four track sections should have a slightly different spacing. Pairs of tracks may be spaced at 44mm centres, but the two pairs in a four track arrangement should be spaced at 60mm centres, (which only requires 192mm) or alternatively the two outside lines at 60mm centres from the centre pair at 44mm centres, which sums to 208mm.

In practice, you will see that the width of the supporting baseboard needs only to run to the outside sleeper ends, so that 180mm is enough for all these arrangements on straight track. Allow the 200mm width on curves.

Now, why you should use flexitrack.

You will save a pile of money for a start. Plain track, which you will need a lot of in that space, bought at the best price available for the 25 yard box will cost you half what the same length of set track costs. Six tracks to go round your loft will take at least five boxes, and you will need at least a couple more boxes for even modest yard space and train storage on a layout this size. (Trust me on this, my layout room is 30 x 10, so very like yours, and it just 'eats' track.)

Next, a flexitrack system gives you access to a superior choice of points. In the space you have using Peco's medium and large radius points will both easily fit and not only look well but also give excellent running reliability.

The flexitrack system leaves the choice of curve radius up to you. My suggestion, nothing smaller than 30" / 750mm. Running reliability is 'perfect' at this radius and larger (given good tracklaying which is easier to achieve at larger radii) and if the locos are up to it a train extending half way around the near 70' circuit that's possible in your space will rumble round all day long (if wished!) .

All the best, and do tell of your progress.

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GeraldH
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Re: Ballasting/sound reduction

Postby GeraldH » Sat Apr 17, 2021 11:02 am

I'm probably slightly unusual, but I ballast directly onto the baseboard with used tea leaves and a strong mix of wallpaper paste. I sometimes tone down the colour a bit with some powder paint. This mix is probably not quite as rigid as granite and PVA. The trains do make a bit of noise, but I quite like it :) .
Gerald H - BNR Correspondent :)

My layout: http://www.newrailwaymodellers.co.uk/Fo ... hp?t=28854


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