It's been done

I've seen pics where people used that. I haven't done it. You're limited in depth by the length of the shelf brackets. If you only want a shelf that's a foot wide, the stuff you linked should be fine.

To get a wider shelf you need to buy the "heavy duty" channels and brackets, which in the version you linked to go up to 24" depth. 

You can overhang the brackets by a few inches, but not a foot without sagging. Some brands of brackets have a little lip or bump out at the end of the bracket to keep a shelf laid on it from sliding off. That makes it harder to have a shelf that extends beyond the reach of the brackets, and is a 'feature' to avoid. Looks like the ones you linked don't have that misfeature.

You might not end up with something that's level front to back, but you can put shims under your cork roadbed and let the rest of the "land" slope if it wants to.

Search around for "adjustable shelf" on this forum and others. 

Those are perfectly qualified

 Those are perfectly qualified for 24" wide benchwork and extremely Strong.  Make sure you screw them into the the Studs.

They are rated for way more than you layout will ever be,  HINT they are shelfs designed to hold heavy stuff.

Do not have the specs at hand but I do think each bracket is rated at 150lb give or take.

Search Function can be your friend

If you enter 'metal benchwork' in the search box above you will get a number of different options.

Also there will be the option to search images on this site, and clicking on any of those images will take you to that posting. I've often found this really helpful to find particular postings. Metal Benchwork Images

There was a gentleman from Europe that posted pics of his version of metal benchwork on my discussion of the subject. But his images disappeared as likely he linked them to another location, then changed that location. I think I still have one of the images saved, and will try to find it.

PS: Here is a link to that Swiss fellows description of his
https://forum.mrhmag.com/post/metal-benchwork-12207979

Floating Benchwork Using HD Brackets

This what I used on my last layout (Blog Florida East Coast, Diary of Mediocre Modeler).  I went one step further.  I purchased the shortest channel and then shortened even more so just enough slots for the bracket tongues.  I had to drill a second hole for another screw. I then screwed the channels into the wall studs.  The benchwork was 24 inch door panels.  Starting a new layout, saved the channels and will use the same method.  Gives a nice clean look to the layout room.

Thats exactly what I used for

Thats exactly what I used for my benchwork, heavy duty brackets supporting light weight benchwork.  I attached a 1x4 to the top of the shelf standard to give a wider area to attach the plywood.  The top is a 1/4" plywood sheet and 3/4" pink foam.  Very light weight construction and a year in so far no sag.  

As far as overhang I think my furthest is about 5-6 inches max.  Any more and I was worried about it sagging.

Work Great

A word of caution though. I found out while painting my current train room in the basement that whatever previous home owner finished the basement, DID NOT use standard stud placement to finish the walls that were up against the cement foundation. They placed a stud every 4 ft so they had some place to nail on sheet rock. And they did not use a sill plate under the studs. There is nothing to attach baseboards to other then the sheetrock.

I also discovered that that not all walls are vertical. One of my basement walls has a very definite slant into the house. I had put a shelf up using the single slot rail and bracket system and when I got done and stood back to take a look at it, and a shelf at eye level just didn't look right. Putting a 4ft level on the wall it was off by 1/4inch for every 4 ft.

Check things before you put up rails and brackets. Could save you a lot of frustration.

Jack

My 3rd use of shelf brackets for a layout...

I am currently using exactly what the OP is showing for the third time. (see my MRH Blog for construction info). The first was 24" wide using extruded foam sheets. The second was 18" wide also using the foam. The first layout was up for 10 years with no issues with the brackets and standards or the foam. The second wasn't up as long but never any issues. 

It is advisable to listen to Jack's warning about non-standard stud spacing. If the wall was a previous owner's DIY project It can be interesting. I had that happen with the first of my shelf layouts.

Thanks all

Fantastic thoughts all - thanks for the input! I will definitely keep this material in mind for future shelf layout construction.

I currently use the more ordinary L-shaped shelf brackets screwed directly into the studs (like in the links below) for part of my layout:

https://www.homedepot.com/p/Everbilt-12-in-x-8-in-White-Heavy-Duty-Shelf-Bracket-14327/206091428

https://www.homedepot.com/p/Everbilt-10-in-x-12-in-Gray-Shelf-Bracket-14819/202947663

With this alternative style of brackets, I like that the "wall-end" of the bracket is not quite so tall in comparison to those ordinary brackets. As a result, it appears to me that it'd be easier to use this material for a double-deck layout. You could conceivably have no interference between installing brackets to support the upper-deck and hanging a backdrop for the lower deck. 

I also like that this system makes adjustment easy, and one can put a frame into each stud once and adjust bracket heights on the fly. Conceivably, this design could make double-deck "continuous climb nolix" style mountain layouts easier to achieve, by allowing you to easily get the bracket positionings just right to maximize clearance for the deck below. And, for any layout, one could minimize the number of times they adjust things screwed into the studs ... I tend to modify things as I go considerably and so it's wise for me to plan for flexibility , and somehow the idea of minimizing the number of empty screw holes in the studs seems rather wise.

Double-slot shelf brackets

That's what the around the walls portion of my layout is supported by. If not that exact product, then the Rubbermaid version available at Lowes. 

in my case we have a long

in my case we have a long hall storage are that I use for part of my layout,  20'x7'. 

When we die the kids can remove the layout and call the place a storage are or pantry etc.  just add shelfs.  No need for them to pull out and solid benchwork etc,  

I decided to go with these

I decided to go with these brackets I bought at Lowes which are rated at 1000 lbs per pair.

https://www.lowes.com/pd/Style-Selections-11-69-in-Shelf-Bracket/3034237

At least 16 feet of the main yard is 2 feet wide.  So I am using threaded rods to support the outer edge.

I am not using foam so this will need to support significant weight of a sandwich of 1/2 inch Homasote and 7/16th OSB.  There will be at least 5 of these per 8 foot section.

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Stability.

It's always a good idea to be sure the bracket will support what you place on it. I built my shelf layout using cheap 10" by 12" brackets from HD (https://www.homedepot.com/p/Everbilt-10-in-x-12-in-Gray-Shelf-Bracket-14819/202947663). And cheap deck screws into wall studs. (If I remember right, 1.5" long.) The foam was three 8' pieces caulked together on end for the 12" by 24' shelf. So light weight that after track and roadbed was laid, could lift 24" of shelf by myself. Then, the 2" foam simply caulked to the metal brackets. Because those brackets and studs are 16" apart, no other bracing was needed. Scenery will also be foam or a plastic product. No plaster for me! 

What are you putting on it

What are you putting on it V8's out of Muscle cars?  1000lb per pair.   That is like Half a Ton or 1 F-150 every 16".   Hydrocal is not a problem for you...  

That product line you linked

That product line you linked to seemed to have no brackets longer than the one you linked. The longer brackets I found were in their heavy duty product line. I was assuming that if you try to plug the heavy duty brackets into the lightweight wall channels, things might not fit properly or be loose. There was a bad feedback message on the product because someone had brackets that didn't fit well in it, he probably had mixed his parts up.

So I didn't suggest heavy duty for the weight, but because if you want 24" brackets, those are in the heavy-duty product line and so you should get the matching channels, whether you need the heavy duty weight support or not.

Also, the weight ratings only give you a rough idea because they aren't describing how much weight at what distance from the wall.

This is what I've used but

https://forum.mrhmag.com/post/shelf-layout-12209802

This is what I've used but you need not be concerned with not having it totally level. That isn't an issue if you use risers because you measure off the laser line not the frame.   What you must have is that it is firm solid doesn't move. I used staple gun and glue for the modal frames and mostly put a screw into back of frame  into the stud. Make sure the metal uprights that the brackets go in are on the studs only. That means your frame has to measure to fit the brackets. I did it for the top roof part to have a floating shadow box look.

@James B Nice clean look

@James B
Nice clean look !

Clean Look

+1 on the nice clean look achieved by James B and Jack M. Those setups really make the layout a showcase and center of focus.

Thanks    ....it doesn't stay

Thanks    ....it doesn't stay like that . But if you need storage in your room  mine is 12'x14' I can use above the top overhang and maybe underneath if I choose to store more stuff but since that photo I've added a addition storage idea in this room to keep some order when I get a chance I'll take a photo. 

The original links

In the thread are broken 

What are you putting on it

Well, you know I am "subpar at best", so figured I should use some sturdy brackets.  You can relate right?  

The more flimsy looking brackets didn't look as good, so I sprung for some more sturdy ones.  I do have some of those adjustable type (topic title) in my laundry room because I needed to mount 3 sets of shelves to increase the storage capacity, something more home often don't have enough of.  

Agreed - I have moved away from adjustable brackets to fixed brackets too.  “Workstation brackets” are more reliably 90 degree square than bookshelf brackets and quite sturdy.  I did a blog post on them but can’t figure how to link directly to that entry, it’s in here:
https://forum.mrhmag.com/post/uglyk5-shelf-layout-expansion-2-was-manifest-destiny-part-2-12217490?&trail=50

jeff