I've never heard of anyone doing this, but a friend of mine wants to add a shelf with a 4th level above an existing and highly functional 3-level free-standing 10 ft. x 4 1/2 ft. layout. The existing three levels are tied together with turnouts and inclines to the smaller second and third levels. The top level provides return to the lower levels via a double crossover switch. The concept is further complicated on the third level by a forested mountain on the opposite end as the double crossover. Has anyone ever seen this successfully done, and if so, how?
Failing that (or even in addition to it), the scale used, and the vertical separation between the levels might help.
The scale is N and the vertices separation between the third existing level and the mountain top is only 3 inches. The concept is further complicated on the third level by a forested mountain on the opposite end as the double crossover. To me, it seems that this would destroy the existing layout's look.
So I guess he's using double crossovers at alternating ends to connect between different levels' tracks. And thus the forested mountain is where the connection to the new, 4th level would logically be located. Would it be possible to tunnel into that mountain, and perhaps have end access to the dbl x-over inside it? While the middle of a long side might not be ideal for a double crossover to/from the 4th level, it might work better than one inside a tunnel, even if end access is available. But in the end, it is his layout, and he should be able to do what he wants with it, whether we agree with it or not.
BigJake, his plan has only one double crossover, towards the opposite end as the level three mountain and there no connection between the 4th level and the three existing levels. I'll pass the thread along to him and maybe he would like to join in the discussion or include his track plan.
Ref. my comment from yesterday, "....the vertices separation between the third existing level and the mountain top is only 3 inches." That should have read: "....the vertical separation between the third existing level and the proposed 4th level would be only 3 inches."