quick question... I'm trying to draw my new track plan right now and I wanna label in my elevation changes. If I have a 3% grade. Whats the formula to get height over distance.
Mike
height/distance.
3% = 3 inch climb over 100 inches.
Chip
Building the Rock Ridge Railroad with the slowest construction crew west of the Pecos.
SpaceMouse wrote: height/distance.3% = 3 inch climb over 100 inches.
JOKER ALERT!!!
The basic formula is correct - for a steady grade. Be aware that you CANNOT change abruptly from level to grade without rounding off the peak and easing the dip at the valley.
If the real question is, "What grade will I have if I climb from level track to level track three inches higher in one hundred inches?" the answer will be, "More than 3%." You will have to allot about 30 inches for vertical easement (15 inches at each end) and 60 of your 100 inches will actually be parts of a vertical S curve, connected by 40 inches of steady 4.2% grade.
In civil engineering parlance, this would be a, "Momentum grade," where the average train would trade forward velocity for altitude. If you want to drag it from a standing start, it WILL limit the length of train a given locomotive can pull.
To hold the grade to 3%, your run, from level to level, would be 130 inches and your steady 3% grade will be 70 inches long.
Chuck (modeling Central Japan in September, 1964 - with 2.5% and 4% grades)
I hope Chuck will forgive my adding to his post. The 15" transition is just best case scenario, and then only for lower grades. As your skills in building a smooth easement fall, and as the type of engine you use has a longer wheelbase, your transitions will actually have to be longer. Yet again, if you need to rise at 4%, you actually have to add that much more transition. Grades, in other words, are the "gifts" that keep on taking on model railroads. Well, on the real thing, too.
Say you want to use a steam engine. You decide that only a 0-6-0 switcher will be used to horse a couple of hoppers up to a local mine. Depending on the steepness of the grade, you may get by with something like 8-10" of transtion into a shallow grade, say an even 2%. Later, someone gives you as a gift a nice 2-10-2. What a beauty!! You place it on the tracks, power it up, and run it into the transition to enter that same 2% grade. You would very likely find it wanting to spin if you had a decent train behind it. It's middle drivers would be lifted off the rails entirely because the outer two driver axles, or probably the outer trucks, would have them suspended and not contributing to the driving. Imagine how much worse it would be if that 10" transition led to a whopping 3% grade!
So, when you plan for any grade, as Chuck has wisely recommended you do, think also of planning for future requirements, and also that you need smooth and substantial easements into and out of grades. They necessarily encroach hugely on limited space for the rise you have in mind.
-Crandell
OK Mike. Since you are building a logging RR, the type of locos may determine the length of transitions that you need. If you are going to be using all geared engines (Shay, Climax, etc.) the transitions can be shorter than if you were going to use a 2-8-0 or something like that.
Even I get confused at times with transitions and grade calculations. What I actually wind up doing is building a test grade. Basically a long board with track on it and extended past it down to the level table top. Then raise the far end to the level I want. Next support the track that goes off the board to the table at several places. Hook up some wires and power for trains, put the train on the track and see what happens. Add or remove cars as necessary to see how the train acts. Modify the grade, length of transition as necessary until you are satisfied. Then take a bunch of measurements that will aid you in reproducing it on the actual layout.
When setting things up on the layout, the easiest way of making the grade and transition is to use the cookie-cutter roadbed method. That way you can bend the wood into the grade you want and the transition is made automatically. After all, you can only bend the wood so sharp before it breaks, so you will get a smooth vertical curve. The thicker the sub roadbed, the smoother the vertical curve or transition.
My method of building a layout and putting in the sub roadbed is a little unorthodox. I don't do a lot of measuring etc. First I build the test grade thing as I have described, to see if the elevation change is doable. Now I know how high I want to go, and the length of run I need to have to make it work. Next I build it, fasten some temporary track on it, and run it. Then adjust if necessary, even if it means that I have to change the track plan a little bit.
To label the track elevations on the plan, make the grade percentage 1 to 1.5 times more than the grade will actually be in a straight change. As an example; if the straight line change will be 3% on the plan, the grade may actually work out to 4% to 4.5% when built with the transitions.
Elmer.
The above is my opinion, from an active and experienced Model Railroader in N scale and HO since 1961.
(Modeling Freelance, Eastern US, HO scale, in 1962, with NCE DCC for locomotive control and a stand alone LocoNet for block detection and signals.) http://waynes-trains.com/ at home, and N scale at the Club.
Thanks Elmer, I'll add to my notes what you have said and definatly take into consideration the transitions. Thanks for the advise.