I have an S gauge layout That operates both high rail and scale equipment reliably. The track is MTH .138 profile. This is the lowest profile that will allow reliable operation of original Gilbert equipment. The profile of the rail, while higher than .100 or .125 is correct so scale wheels operate fine. The challenge is the turnouts. They are readily available in .125 or smaller rail. AM makes #5 turnouts with their .148 rail that can be mated to the MTH rail. The AM turnouts require modification to allow scale wheels to operate reliably. I elected to have all my turnouts hand built with the MTH rail. Almost all the turnouts are #6 and #8 except the freight yard at #5.
Track radius (and clearance) depends on what you want to operate. I chose 30" as my minimum as a compromise since the room was not very large. I tried 36" but could not make the track plan work. Almost all engines made will run on 30" except some of the River Raisin and another boutique manufacturers scale brass. The layout accommodates up to the scale 80' AM passenger cars (their standard ones are 72'.) The trackside clearances will not accommodate modern prototype freight such as 89' high profile freight cars. That was a design decision on my part. We used the Big Boy for engine clearances as it is oversize for S.
The ruling grade is a 2.5% 250" long grade with a 36" radius 90 degree curve. All curves have easements and superelevation. All the engines with traction tires can pull 15 Gilbert freight cars up this grade without working hard. The scale engines need to be operated as per prototype as MU. This is really easy to do with Legacy. Two scale wheeled American Models PA units double headed will pull 6 AM passenger cars up the grade. Eight cars would likely require a 3rd engine.
The layout is designed to run with Legacy along with the Lionel LCS. Track power is two ZW-L's. So far there are no S gauge DCS engines, we will see if one shows up from MTH this month. DCC could be added but I left it out since I have no DCC engines. If I buy a Brass engine I will put TMCC and Railsounds in it.
I have posted pictures of the layout over the past 4 moths, you should be able to find them from my profile.
