I have been experiment in HO to find out how long easements should be with a 2% grade. They were very important when I did a 4% grade on last layout but with all my experimenting on 2%, you don’t seem to need much. I run short stuff both steam and diesel and the longest car (flat car) at 50’, all others 40’ or less and shot trains. Also I am talking functional, not visual (I will give it all the extra room I have for that.
IMO, this is one of those problems that you have to defy common sense to create. If you keep joints in the subroadbed away from the vertical curve, use 1/2" or thicker plywood, and firmly attach it to at least 2 risers before the vertical curve, you can’t bend it enough to cause a problem.
PS - real plywood - not OSB. OSB is satisfactory when used in sheets, but not in strips as in cookie-cutter subroadbed.
PPS - it should go without saying but no turnouts on the vertical curve.
I used OSB on my last layout and didn’t have a forumula. But I needed to go from no slope to 2.9% so I did it over approx 16 feet I’d guess. I started with slight grade of maybe 0.8% for around 4 feet, then 1.4% for another 4 and then 2.1% to maybe 2.5 and finally 2.9%. That way the grade change was fairly gradual but controlled. I didn’t have any issues with couplers mismatching or anything so it seemed to work fairly well. What I listed isn’t exactly what I did but from memory as it was about 5 years ago.
I am using Woodland scenics inclines on a foam base with cork on top, works flawlessly.
I used cut-out 3/4" plywood as subroadbed, and it forms its own vertical easements as the risers are added.
With ground zero securely fixed in place, and likewise the highest point of elevation, I simply add a riser at the mid-point of the grade, putting the height of the roadbed, at that point, at one-half of the total rise. All that’s needed then is to install intermediate risers that meet the lower face of the subroadbed at its then current height, neither pushing it up nor pulling it down.
Wayne
But naturally the elevation of the risers is going to form/force the easement and grade so the riser height needs to be figured and deliberate. I measured the distance between risers and was able to calculate the grade needed to transition, over a distance, from one grade to the next to reach the maximum grade.
That’s way too much. 16 inches would have been a better choice. If you had a 16 foot transition at both ends, your grade in the middle would have been significantly steeper than required.
From March 79 MR:
Well I have done some experimenting. Now this was all done with stuff I plan to run so my observations will not apply to larger stuff. I tested with 40’ boxcars and small engines like a Proto 0-8-0. You can accually get away without easments on a 2% grade (very small coupler height change and looks fine, small easement looks a bit better with a very slow moving train). Now with a 4% grade it still works but coupler height change is more noticable, dosn’t look as good. Add a 2" easment and it looks ok and functions fine, 4" look great. So I will go with about a 2" easment at the bottom and top and will give it more if I have the room on my 2% grade. Never had problems with room in my old house, downsizing dose have its cost but I do have a heated enviorment controled room now. Would not be asble to work on old layout for alot of winter and don’t have tgo worry about noise bothering tenents above a garage.
I could be over estimating from the transition distance from memory, but I was being very conservative.
OTOH, I’d think 16 inches would be way too little distance to change from 0% grade to essentially 3%, especially with the coupler off-set that would happen with 89’ long freight cars. Heck, an 89’ freight car is about 12.5 or maybe 13" across the pulling faces so I fail to see how 16 inch transition is going to keep couplers from mismatching at the transition point. Even modular layouts with no grade transition but not well leveled can cause long cars to uncouple.
Sorry, my point (less than clearly stated) was that 16 inches is way closer to the “right” answer than 16 feet.
shouldn’t the length of easement depend on the change in grade
and the purpose of the easement is to limit the change in grade to avoid coupler problems
Yes, check the formula in the MR article I posted.
That’s one of the issues, but you also want to keep all your wheels on the rails and the flanges between them. A 2-10-2 might lift the center drivers off the rail or a long car with a small amount of play in the bolster might lift wheels off the rail. Also, a locomotive pilot or coupler air hose might dig into the ties.
I was being very conservative on my last layout with the grade change. The truth may be somewhere between 16 feet and 16 inches. I would think several feet transition would be needed for long cars to avoid mismatches, at minimum.
Thats why I tested a 0-8-0 which is the longest ridget loco. Don’t have a -10- to test.
No, it worked exactly as stated: fixing both the bottom and top of the grade, then putting a mid-point riser at half the total height allowed the plywood to form a gradual easement from flat to inclined, at both bottom and top of the grade. I can’t say what percentage it might be, but don’t really care what it is - it works, with no surprise uncouplings or locomotives lurching into a grade, whether up or down.
Formulae are great if you understand them, and want to make such calculations, but this seemed to me to be a simpler way.
Wayne
I actually do have a curved # 7 1/2 L.H. turnout on a 3% grade with 32" radius overall curve and it works fine. I used a Shinohara turnout and a Tortoise switch motor. I will say it was the most difficult turnout and took the most “tweeking” of all the 21 turnouts on my 12’x8’ HO layout.
I think that you are actually saying “do not place a turnout along the transition from horizontal to vertical.” And you are right! That would not work. I have read, however, in the past to avoid turnouts along a continous curved grade.
Turnouts, curved or otherwise are fine on a grade, but you don’t want them on the vertical curve that is the transition for a change in grade.
Back to vertical easements. I’ve transition from no grade to 1.8% in about 48 inches.
First from 0 to 0.5 over 14", then 0.5 to 1.0% over13", then 1.0% to 1.4% over 14", then 1.4% to 1.8% over 26". Then maintain 1.8% for about 8’.
Main concern is long car coupler offset at transitions. Seem reasonable?
That seems overly conservative, but fine if you have the room. Clients and friends seem to be OK with about one longest-car-length per percent of grade … or even a little less in a pinch. Just make sure that you have another longest-car-length beyond the transtion before any turnouts.
Byron
My new layout will require a 5% grade to do what I want in the space I have.
I mocked it up with Kato Unitrack and scrap plywood I had on hand to verify it was possible. Ran FA locomotives and 40/50 foot freight cars with no problems and no special calculations.
Maximum train length with th FA was four freight cars and a caboose.
-Kevin