I am in the process of expanding my current layout by creating a yard. My exisitng layout is L girder with 1/2" plywood, WS foam roadbed and a mix of Atlas and Peco Code 100 flex-track using Loctite Polyseamseal adhesive caulk. The expansion area, due to a number of construction constraints, is primarily box-frame with 1/2" plywood, 5/32" cork roadbed, all ME code 83 flex-track and turnouts and ditto on the caulk. Unfortunately, I went the cork route in the new yard area as I wanted a lower ballast profile in the yard than the WS roadbed gives for main line track. Now the existing 6 year old layout has always been completely satisfactory from a running noise standpoint. So far, in running a couple of locos to test the new expansion sections of track, turnouts and curves I have laid I have found the running locos really really noisy. Since I laid all of the roadbed and a significant length of track before noticing the noisy operation ripping out and starting over is not exactly an option.
My question here; is there anything I can do to deaden the sound once I am this far along? e.g. - will the addition of scenery and ballast absorb unwanted noise? Adding additional support members / struts under the plywood? Attaching non scenic foam strips / sheets under the plywood? Any kind of special sound isolation foam? etc.
Most likely yes. The original section is scenicked and the new is not? That’s going to make a lot of difference. Scenery generally muffles and suppresses sound.
Stick some sound absorbing mat (like they use for car audio installs - there are cheap knockoffs of the Dynamat brand which is expensive) in some of the empty box sections (ones that don;t have switch machines, if you use under-table switch motors). Against the bottom of the plywood. That will dampen the sound.
Scenery on top will help - anything with some stiffness anyway - just paint and ground foam won’t do a whole lot. The idea is to change the resonating characteristics of the boxed plywood sections.
IMO, there is a noticeable increase in noise once the ballast is glued to the plywood, whereas leaving it lay unglued is more quiet.
As I consider how I’m going to build my next layout, I have heard good results from placing waxed paper on the plywood next to the roadbed and spreading ballast and gluing it whilst on the waxed paper. Then, since water and glue wont stick to the paper, pull the paper out after its hardened. If successful, you shouldn’t have a direct connection between the track and the benchwork, which should minimixe the vibration caused by the trains. (I also wonder if you could just leave the waxed paper in place underneath the hardened ballast)
I have personally found the quietest way to lay track is on top of cork with nails to hold it down. The ballast should NOT be glued down.
Something about fixing the track in place causes more of the sound to be transferred back up as the train runs over it.
And if you think about it, it makes sense. In professional home theater installs, all the walls are floating (use RSIC clips or Green Glue over drywall). This means they aren’t load bearing, and they aren’t hard connected to a floor or ceiling. This allows them to absorb sound instead of acting like a reflecting surface.
Interesting. Most everyone these days seem to glue their cork or roadbed material down as well as the track.
In my case, originally learned how to lay cork and track by nailing it and it works well for me. I have put some ballast down on one section of my layout but it hasn’t been fixed in place with glue yet. Interestingly, I have run trains a number of time and they are very quiet - hardly any sound.
That’s my opinion as well. And, to take it a step further, ballasted track is noisier than unballasted track.
My layout sits on 1/2" plywood with a foam (Woodland Scenics) roadbed. I have sections of unballasted track, sections of ballasted track but not glued, and sections of glued and ballasted track. The unballasted track is the quietest.
BTW, I use matte medium because the LHS guys told me that it is quieter than white glue.
The short answer is “No, you can’t add anything to the layout to effectively reduce the noise from the trains.” Adding absorption, as some have suggested, will only reduce reverberation levels near the absorbing surfaces. The direct sound will not change, only how long it reverberates in the space. If you want to duplicate the sound level of the previous layout construction, the only thing you can do is rebuild the new section using similar construction methods and similar quality materials. As soon as the construction method/quality changes, you will get different acoustical results.
However, I have always noticed that prototype trains make one heck of a racket as they pass. As a professional acoustical engineer, I have had numerous opportunities to measure sound and vibration of trains. I find it amazing that a flat-spotted wheel on a freight car often produces higher noise levels than the locomotives. Add brake and flange squealing, various moans and groans of the car chassis and suspensions, plus miscellaneous impact noises from loose doors, panels and loads and you get trains that makes a lot of noise. To expect our model trains to whisper around our layouts is not very prototypical.
I’ve noticed a huge difference in sound using scenic cement vs white glue. White glue was extremely noisy. The track sections with ballast secured by scenic cement was dramatically quieter (in both instances cork glued to1/2" subroadbed with white glue; track secured to cork with caulk). have not tried matte medium but will be testing that when I start ballasting new layout this fall. BTW, last layout used WS ballast (from what I understand it’s crushed acorns), this one will use AZ Rock & Mineral ballast (Real rock). Anyone noticed a sound difference based on ballast type?
some of the members of the modular club i belonged to had a similar problem one just screwed 1by2’s to the bottom of his and it seemed to quiet it some (took noise level down to bearable) the other got several cans of that expanding foam and sprayed the bottom it made the noise level almost nonexistent.
Please note that both of these “fixes” reduced the sound by adding rigidity and/or vibration dampening to the plywood roadbed. Expanding foam insulation is not an effective sound absorber as its surface cures too hard. However, it will maintain some level of resilience that can help dampen sound vibrations in the plywood panel to which it is applied but at the cost of filling the space you planned to use to host wiring, switch machines, light fixtures, etc. On the other hand, it could be used for both sound dampening and scenery by applying it to the top of the plywood and carving it into hills and mountains, assuming your layout could use a few mountains.
Materials that are thick, soft and fluffly (like open batt fiberglass insulation) make the best sound absorbers but are actually poor sound barriers. Note that absorptive materials affect only the amount of reverberation within the treated space. Absorptive materials have no effect on the direct sound level coming off the rails. Also note that adding lots of absorption materials will not only abosorb the sound you don’t want to hear, but will also suck up the sound you do want to hear. Not an effective fix!
Thanks, everyone, for your consideration and responses. I believe at the moment I am going to complete my layout expansion as planned, including backdrop, scenery elements and fascia and then evaluate the sound problem, if any, at that time. I’ve done some searches which has led me to a number of sound “absorbtion” products which are advertised to solve the kind of noise problem I am experiencing (i.e. - vibration amplified by a large flat surface area). Should be a couple of months but I will make a point to report my findings and solutions back to this thread. Thanks again, Geoff