20' x 4' Suggestions welcome

What kind of trains do you prefer to run?  The answer will inform the sweep of the curves and length of sidings.  The 4-foot constraint puts a limit on running larger steamers and it will cause overhang on many passenger cars.  Do you have any flexibility at the ends to go wide enough to accommodate O72 curves?  The S-curves on the loops might present a challenge for longer equipment.

How about flipping the whole thing and put the passing siding along the wall? Brings the bottom closer to the front edge and allows for more scenery in the middle. Probably have to widen the inside corners of the bench to fit the curves.
Assuming you're going for a mostly scenic layout.

Bob

Any chance you could use the long run to gain elevation for an upper section?   Maybe hide the siding under the mountain?

> Get rid of the "S" bends.

> Include two wyes, like the one in the second picture, to be able to reverse direction. One of them could be on the top level.

(I like the "through the wall" idea )

Dave

I like @RSJB18's suggestion to include the passing siding at the back.  I was wondering how this might look, also adding reverse loops and increasing to O48 curves and switches.  Just for fun and to see the pros and cons, I made this quick plan of sorts.

To accommodate the larger curves, I widened the bench to 54".  This presents a reach issue to the back corners unless there's ability to walk around the layout.

The track in red is where I considered eliminating the s-curve by shortening the lobe curve and adding a short straight between the curve direction change, but this would further increase the reach to the inside of the lobe.

Anyway, this concept has issues, but may better help visualize the challenges.  The SCARM file is also attached.