I’m hoping someone out there can clear up a few questions for me. First off is there a maximum elevation a train can go, I know it probably depends on a few factors such as size of the locomotive, weight of the load ect…ect… What I’d like to know is if there is a certain height you should not elevate beyond or is it strictly a question of the elevation grade, it would seem the elevation kits available plateau at 4%, 4 inches inches in height and I’m wondering if there is a reason for this. Reason for wondering is I have a 6 inch height I would like to get my train to climb so I was figuring I would use the 4 inch kit then add a 2 inch kit on to the original 4 inches keeping the 4% grade until I’ve reached 6 inches. Does this make sense, and will it work? Any help would be much appreciated.
The maximum elevation a model train can reach is dependent on the geometry of the space where the layout is being built. Theoretically, it would be possible to peak out at NMRA clearance between the railheads and the ceiling. Practically, John Armstrong recommended a foot of clearance between the ceiling and the railheads - but he was hand-laying that superhigh track in place and wanted room enough to use tools up there.
On my personal layout, the coal-originating short line will be built on a near-continuous 4% grade, so the upper terminal will be about 24 inches above the lower terminal/mainline interchange. That length and steepness of grade is uncommon, but not unusual. OTOH, my mainline ruling grade is 2.5% (same as my prototype’s) and I limit the grade on (to be) hidden track to 2%.
So-called elevation kits are not the only way to provide for grades - or even the best way. I personally use a thin plywood subgrade under thin extruded foam roadbed (fan-fold underlayment) and cookie-cut the plywood, which is then pushed up with risers of appropriate length screwed to the joists and girders of an L-girder benchwork structure. Starting with a solid tabletop is more difficult, but not impossible. One possibility is to use just enough of the commercial kit to get the grade started, then shift to a length of plywood (or pine plank) once there’s room enough to fit it and its supports between the ties and the tabletop.
I think you can see that planning the layout for grades from the beginning is a lot easier than trying to provide for one as an afterthought. This came easy for me - I have a master map of my overall concept. It’s dated 1965!
Chuck (Modeling Central Japan in September, 1965 - with some long, steep grades)
It is a combination, and compromise, between what the engine can do and what you can reach if the engine doesn’t. Every engine is different, obviously, but they all have measurable limits on grades. The responsibility for determining that rests with the user. What we recommend is to mock it up temporarily and do trials with length of cars and with different grades. Make darned sure you keep accurate notes of accurate grades. Don’t sabotage all your effort, and your future fun, by being sloppy with a rickety and uneven grade that undulates and gives your engine fits. Spend some time and lay a good grade with a bottom easement into it (the vertical curve leading into the grade) because that is also a necessary determination for all the engines that will use the grade…especially important for steamers.
Your 6" height is arbitrary, and you should not hold fast to it. However, you still call the shots, and you have to determine if 6" is darned well what it’s gonna be! If it is to be 6", the question incumbent upon you, the user and builder, to determine is, “How to achieve it in the space provided?” You may find that it will need an eased 7.5% curve in the space you have for the “run”. Well, if true, good luck to ya. I hope you are prepared to run double-headed engines pulling only 12 boxcars…if you are lucky. The fact is that the first rule to keep in mind centres around real world grades, and they are exactly as problematic as are the scale grades. That’s because a grade in HO is exactly like a grade in the 1:1 world. Rise over run, the formula, leaves a ramp looking parallel to the same dimensions in any other scale. You are stuck…you either compromise in the run and live with less rise, or you find more run to get more rise, or you find heftier engines to tow your loads. You can’t have it all.
To your question of the risers, or rather ramp s