Part of your question comes down to "what can you find"? Homasote seems to be difficult to find in some places. Cork is everywhere of course. Cork will also require less preparation if you are buying the precut strips - probably even if you use the Homabed product available from http://www.homabed.com/

I'm a firm believer in Code 83 Flextrack - it just looks a lot better than Code 100.

Hello Dave

1st I wouldn't use Just Foam as roadbed as it amplifies unwanted sound 10 Times but, there is nothing wrong with using 2 inch Blue Contractors foam as a sub base with proper wood or steel support under it.

I personally use Homosote for large flat areas like yards and industries. I then use Cork roadbed on spline or on1/2 inch plywood sub roadbed every where else and that 1/2inch needs to be sported every 14 inches and the spline every 20 inches. I find the 1/4 inch hardboard (Masonite) cut in 1-1/8 inch wide strips actually makes the best sub roadbed Base and I then add cork on top of it and it really deadens unwanted noise you will need to use as many strips as it takes to get it 2 inches wide.

After you get the first piece of 1/4"  Hardboard in line the spline goes together fairly fast and you can lay track the next day after the glue between splines dries. As  far as spline pieces  I add 3 to one side of this center spline and 4 to the other for both my HOn3 narrow gauge & duel gauge  sub base areas for a total of 2-inches of sub base for both narrow & duel gauge.I could get away with 7 strips but the extra 1/4 inch leaves me something to attach scenery too on both sides.

I normally get 32 to 34-8 foot spline strips at 1-1/8 wide which gives me enough  to make 32 feet of sub roadbed or four complete 8 foot sections of sub road roadbed 2 inches wide from one 4X8 foot sheet of Hardboard (this is if you have a table saw or know somebody that will cut it for you) also remember to stagger each piece of spline 2 inches so that as you add each section they fit together like fingers to enter lock each 8 foot section to the next

TRACK

Personally I would recommend Code 83 ME Non Weathered Flex Track for your duel main tracks and code 70 for Sidings and Yards if your planning on building a modern 1960 to the present  Diesel Era Pike.  I use code 70 for mains and code 55 for sidings but I'm modeling totally in the steam era and for the most part Narrow Gauge HOn3.

As far as Code 100 in my opinion it looks like toy train track and is way too big but that's just my opinion.

Dan

I saw a product from Woodland scenics called Track-bed..comes in 24 foot rolls. It looks like closed-cell foam.(?)

Looks easy to put down and not too expensive. Was thinking of trying that at least on my behind the scene helix. I assume it will make  a 28" curve..... 

Any opinion on that product?

and honestly, didn't like it that much.  I just found it a bit too spongy.  I wanted a more solid roadbed, but it does reduce sound more than cork.  I'm sure others have tried it and liked it. 

I like using woodland scenics foam raodbed, it is soft but I see no issues with it being so. I use liquid nails for foam to put it dowm spread smooth and thin it is actually removable with a putty knife. I have tried some off brands of adhesive but liquid nails seems to have the best working time for me, and the fact that if thin enough it is removable without destoying the foam is nice.