What did you (are you going to) choose for your vertical easements, or not choose? And how did you (going to) measure it or set it as you built (build) your layout?
For example, in HO I am considering somewhere between a change of 1/4% per 10" and 1/2% per 10".
Thank you for your input.
Just going to try, as always, to avoid both kinks in the trackwork, and too much math.[X-)] I build on the principle that what “looks right” generally works. (Sort of like ships, some of which just look beautiful, and some of which look like cows and sail the same.)
I read in MR that horizontal easments come haturally when you use spline roadbed…I would guess that your sub-roadbed is plywood and that when you set your grade that the vertical easment would form at the start of your grade. Just my two cents…
But if the spline sub-roadbed is a stiff material, and most tend to be [:O] won’t the vertical easement be a function of the grade, just like any other sub-roadbed method? I rather think keeping the grade low at the start and end of the slope (by eyeball in my case) is the way to go. [2c]
If you use “cookie-cutter” style construction for your sub-roadbed (or sub- sub- roadbed in the case of spline) your vertical easements are worked out for you simply by bending the plywood.
Andrew
Never bothered calculating it!
Concave is easy as pie, convex is almost as easy if you let the plywood do the flexing, if necessary groove it so it bends easier.
I usually allow 350mm (for HOm on 3.5 % grade) on either side of the theoretical intersect. I guess I could figure out what that is using CADrail.[:)][:)]
Hi Nigel,
“Vertical curves” is the more commonly used term for these. My experience is that for HO scale on 3/4" plywood subgrade, you don’t need to worry about this because any curve you can bend in the wood will be okay.
And thanks for signing your name.
Good luck,
Andy
Andy and all: I’m drawing up my next model raillroad section using CadRail 8. I’m trying to figure transitions/easements to a helix with a constant 3 % grade, at radius 26 in. I have only SD45s and earlier diesels, but 50’, 60’, and 72’ (centerbeam) freight cars, and some 85’ passenger cars.
I realize I’m going to have to mock-up the transitions for final design. I use 0.75 in. plywood generally, but will probably go with 0.5 in. plywood for the helix, to clear double-stacks, etc. So in the plan, before making decisions on overall layout pieces, I want to be able to include a ‘length’ of needed transition between flat and 3% grade.
It would seem there might be some ‘rules of thumb’ about lengths required for these transitions, given the specifics above. There seems to be a lot of experience, but no general guesstimates on lengths for transitions. Surely somebody has an opinion or two before I start cutting plywood.
I’d be most grateful for any input.
Dick Chaffer, Bozeman, MT
Escaped from the Emerald City in 2000
If you are dealing strictly with diesels, six two or [edited] four three axles per truck, you should be looking at 3"/half-percent rise change. Steamers will want between half again and twice that if the models are not sprung, although smaller engines like Moguls and Prairies would be okay near the same rate of change in grade as that for diesels.
-Crandell
Running comparatively short-wheelbase steam and ‘long’ cars of 250mm length, I allow approximately twenty inches (500mm) per percent grade change, centered on the theoretical point where the extended grades intersect. I use cookie-cut plywood as a subgrade and make sure the transition is properly shaped (beating it into submission with extra risers and steel angle iron if necessary) before adding the comparatively thin extruded foam roadbed.
Note that the same formula is used between changes in grade (500mm for a change from 2% to 2.5%, 2 meters for a ‘hump’ between 2% up and 2% down) as for changes from grade to level.
Chuck (Modeling Central Japan in September, 1964)
Thanks to you both for the quick replies. By chance, I’ve already allowed about 41 in. (length) for the transition from 2 percent to 3 percent. Time for mockups. Thanks again.
Dick Chaffer / Bozeman, MT
Your planned transition length is quite conservative, and if you really have that much space everywhere, you should have no problems. But I will point out that, using the same criterion, you should have 123 inches (that’s 10 feet!) to get from 3% back to level at the end of the grade.
If it turns out you don’t really have that much length available everywhere, the right answer is perhaps somewhere between selector’s 2% change for every foot and Chuck’s 0.6% per foot - I use 1% per foot, but I don’t have any steamers longer than 4-8-2’s. Certainly if you have space for a more gradual change, you’ll never regret it.
If I may offer my 2 cents, and while new to these forums (but a long time MRR subscriber), I’ve built numerous layouts over the +35 years I’ve been in the hobby (and currently building a new/last one since our move to retirement condo life…).
With respect to elevation gains and decreases my “standard” has been a 1 inch rise in 4 feet, or 1/4 inch per foot, which works out to just over a 2% grade, with the first 1/4 inch of rise or last 1/4 inch decrease transition from or to level 18" in length vs the regular 1/4 inch rise or decrease per foot increments.
Using the mid point between the highest and lowest track levels on my layouts for my “level” areas allows a 4 inch grade/track separation in a space saving ~ 9 feet vs a longer ~ 17 feet to reach a 4 inch track separation.
For my hardware, a mix of 4 truck diesels (and 4-6-2 steam when I have the patience to mess with the associated mechanical operational issues …) I’ve had no problems with the initial 1/4 inch rise or decrease in grade in 18 inches.
you need to ask your self what am i looking to model is it a mountin range and i want to go through a gorge or do i want foot hills where the train goes through hills that have ben cut away a gorge can be really high but in modeling you really dont want to lose sight of the train with that said my anser would be dont make it to high mybe the hight of 2 engines high and 2 wide