Grades add interest to the operating of our railroads.
Every Model Railroader I know has built a long consist only to attempt to add 1 more car.
The longest successfully operated train on my tracks was 54 cars…and that is on the the main line oval—and it has a slight grade transition…
I know that if I took the time to set out the rolling stock in a weight based order, I could get 75 cars…but nothing I have would pull them up my steeper grades.
The focus on grade percentage is a nice to know aspect…
The OP has a 9.5’ x 12’ area..to attain 6” of clearance off a reasonable grade climb, that’s 100” or more of linear trackage…and chances are almost 100% that there will be a 36” curve in the riser…
That will limit train length-but will add operating interest; splitting the consist or adding a helper engine.
So the plan should include a spur to park the helper engine near the grade.
This is an older video, during the beginning of construction…but after the date my wonderful wife discussed the possibility of moving-20 cars plus 1 5 car unit-technically 25 cars😁
Behind a Switcher, that struggled a little
the grade starts at about 18.5” from the ceiling..
and climbs to 6” from the ceiling
So 1’ in just under 20’
12”/240”=5% grade
With two opposing O-72 curves.
Here’s a look at the whole road
Good luck
