Train table questions...

Describe the benchwork, please.    

Unless something has changed since I last used it, homosote will sag if it doesn't have plywood or something similar underneath.
There are other sheet goods besides plywood that can be used. Oriented strand board is one possibility.

Whatever you use, some framing will be required.

Homasote is a sound-absorbing material (at least in model-RR applications), and doesn't really have enough structural rigidity to be the primary load-bearing 'tabletop'. You typically install it atop the plywood, and then trackwork attached to the Homasote is anchored with screws short enough to avoid reaching the plywood (as that would defeat the sound deadening aspect)

Trolleys don't pull much of any amperage at all, so wire gauge isn't terribly crucial (18-24-ish) if that's the only traffic that line will see. If the trolley loop is especially long, (which seems to be uncommon except for dedicated traction layouts), you get much more performance from having extra power feeds attaching to various points of the loop.

---PCJ

I have homasote on top of plywood and love the results. Table is 6X12 and has been up for about 3 years with no issue. A lot of dust cutting it so I suggest that be done outside if possible.

Thanks for the info.   Layout is  8 x 8, so it will (or should be) an  easy rebuild.  My challenge will be the wiring.  I plan on having several drops (I have three loops and a point to point).

The biggest difference in the new layout/table is that my current one has had artificial turf as the covering.  In addition to being difficult to work with, I'm not fond of the appearance.  My plan is to paint the top with a fairly neutral color so I can adapt various scenes and landscape a lot easier.  

I also think accessories will look much nice.   The one thing I need to do is figure out a way to cover the space between the  4 x 8 boards.  Any thoughts?

Thanks again!

TrainFanStan

Reconsider the conventional use of wood or wood products and instead use hollow aircraft aluminum 2x4s, angle plates for bolting and 2 inch x 4 foot x 8 foot pink styrafoam sheets for the table top.  Very easy to work with.  Just put cross tubes inside the outer frame to give added strength and support to the table and the top.