Starting from the usual 9 3/4" curves, we have widened the loop on the left side and added a passing siding inside. Top right features a yard of sidings.
We close the loop inside, and add sidings to the bottom. We have added an optional reverse track (alongside grey strip). This requires special wiring and must be insulated off, and a device such as the Atlas controller. (The controller comes with wiring and insulating instructions) The reverse track is option. Some enjoy using them, some don't. If you want, you can omit it without losing the integrity of the layout.
Scenery can include a mountain, making for tunnels on the left end. Optional reverse track is show, though you can delete it if you desire.