Simplified Grades and Switchbacks | Workbench Wednesday
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- čas přidán 9. 09. 2024
- For this week's Workbench Wednesday we have a quick tutorial with some easy shortcuts for calculating model railroad grades, with illustrated examples for gaining track elevation using loops and switchbacks.
Amazingly, I guess I need to add that this topic has been simplified to be easily digested by non-engineers and beginners in the hobby. This information should in no way be used to calculate grades in the real world. These are quick shortcuts for model railroaders only.
Thanks for watching!
Dave
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Don’t forget those transitions or easements into those vertical curves, especially as your ruling grade increases. Otherwise, your train may break in two when the couplers disengage.
Good point
While planning and building my Twin Peaks layout. I came up with another solution. Think of it this way, you need four feet to reach your highest point, but you only have three feet of room. Picture this, take four feet of string and bunch it up, light a highway going into the mountains and shorten it to three feet with "Curves". Yes, you have curves, and like you mention it slows or makes it harder on your "Shays". So, start with four and a half or maybe five feet and add easy wide curves to shorten to three feet. Not only does this help with the solution but makes for some interesting mountain scenery. I have found One drawback, no matter what, Wach your speed coming down the other side. You and I really need to turn down the power on the downside.
Planning the grades is vitally important. Building them is another thing and a time when accuracy is equally important. Woodland Scenic's foam inclines keep you from cheating and guarantee the grade is maintained throughout it's length.
4% compensated grage. In real RR terms. I was a former Surfacing Gang Foreman. Don't forget to spiral into a curve , don't just start it. Blend it into your maximum curve radius it will run better and look cool. And don't forget one hundred scale feet between opposing curves. Or thirty (or maximcar length) feet for narrow gauge. That way there's no binding in the couplers.
I liked this video very much. The switch back section is where mind was going in my On30 pre-plan to paper stage for my logging layout. In other words you put to visual what my brain was attempting to work out scene vs distance. Again enjoyable. 🙂👍 Thanks Dave.
Very good video on an important subject. I learned the hard way that if your engines don't have traction tires, you can forget anything over 2%. Good video!
Thanks! Got a 12’x30” center section of dog bone layout space. Logging/ mining theme in my head. This Helps a bunch
I look forward to this vid as my current layout in planning has a switchback. perfect timing
Thanks for this Dave. Excellent information to use in planning.
Dear Sir!
🤣
Cheers from civilised metric Brazil!
+1 on planning your grade transitions/vertical curves. From my experience with On30, you can go from 0% to 1% with little worry. 0% to 4% is a different matter. You will need a vertical curve at each end of the grade to ease in and out of it. That translates into an added run length requirement. The actual varies with grade. I use 2" x grade% on either end of the grade as a rule of thumb. A 4% would need an additional 8" on either end.
On my G scale layout I have a 50’ section of mainline that is a straight 4% grade… boy does that create some exciting operation for live steam! All of your projects are absolutely world-class, thank you for sharing all of your work!
Such a helpful video and great advice!
Thanks for that every important info on grades. Can't wait to see how it turns out on your layout.
GOD BLESS 🚂💖🚂💖🚂💖🚂💖
Cass Scenic RR in WV still uses their switchback on one of their runs. They say it's a tricky ride when the leaves are falling...
Yes, and the grade is around 8% until just before the top of Bald Knob where the grade becomes 11% for several hundred feet. Listening to three 3-truck Shays pushing 7 cars up that grade is music and not easily forgotten. After the train stopped and the passengers got off, 2 of the locos went back down to Cass; only 1 loco was needed for the brakes when drifting down the grade.
Great tutorial...Thanks!!
Very thoughtful video! I have been reverse-engineering John Allen's classic 4x8 Gorre and Daphetid with the aim of compressing it as much as possible, and the point about curved gradients hadn't even occurred to me. I really liked learning your technique for getting the grade heights from track distance on paper, I was wondering where Allen got his heights from!
I have a switchback modular layout which is exactly 5' 6" long, with each tail track being just long enough for an 0-6-0 tender loco and two short logging buggies to fit, or a two-truck geared engine, the two log cars, and a four-wheel caboose. As a visual gag, the sawmill at the bottom of the railroad is only a few scale yards away from the mountain top, showing off the elevation. I painted a little "hiking trail" to imply that the railroad genuinely takes a 2 1/2 minute round trip to cover a very easily walkable distance of about 30 scale feet. One thing I discovered is the "vertical curves" presented much more of an engineering challenge than the grade itself, since it's in such a confined space. For instance, the switchback itself could only be 2% either way to avoid cars uncoupling, but on the actual tail tracks, I could make it get progressively steeper, closer to 4%. Part of this was to give the illusion of climbing a steeper grade, and another part of it was to allow for "gravity trains" where the log cars at the top are just left to roll down the mountain unchecked. To get more track to fit, two of the tail tracks are on 15" curves that go into the backscene.
Santa Fe had a switch back at Raton when the railroad was first built.
For non american standard gauge swithbacks on a mainline look up the Lapstone and Lithgow Zig Zags in NSW Australia.
Thanks for this Dave. Any thoughts on how you will construct the elevation changes? I am going to assume insulation board and not incline/decline sets. maybe plywood base? I am starting to think about an elevation change but it is going to require a sharp 15" curve about 1/2 way up and not sure I want that.. thanks again for all you share.
Up Up and Away
Dave, I have an unrelated question for you. Do you add weight to your rolling stock? If so, I think you have mostly Bachmann freight cars. In addition to the question I already asked, I'd like to know how you get the Box Type cars apart to install the weight?
Dave, I think the math in your first example was off a bit. If you have a 4% grade along the first 25", you will be at 1" of rise. But if you cut back to a 2% grade along the curved section, you'll only be at 1.5" of rise at position #2 (50" of run). And if you carry that same 2% through the rest of the turn, you'll be a 2" of rise at position #3 (75" of run). Or am I missing something?
Yes, on the curve I'm counting two inches because it would only be .5" every 25".
For you metric people, for every 1/4” meter, your track should rise 1/25th of a meter. 😊
Hello Dave ! :) In a friendly way and only in order to avoid people maybe getting confused (just in case they would need to apply this in real life and not on scale models), I am sorry but I think that I see two mistakes in what you said at the beginning. The first one, although its effect is negligible in practice for the actual used grades, is in fact mathematically wrong. If your rail is 100 inches long and your elevation is 4 inches, the grade will be 4.003% and not 4% :D:D The way you present it by saying "length of track" is misleading to me. The length of the track for 4% on 100 inches is actually 100.08 inches. :D:D I know that it sounds ridiculously "quibllely" (I don't know if this is even an existing word :D, but I guess you see what I mean, "cut the hair in four" as French people say, "rivet counter", "picky", I guess ) but for maths accuracy, I wanted to mention it. For example, for a 30% grade, your rail will need to be 104.4 inches long and for 100% grade it will need to be 141.42 inches long. 100% grade is an angle of 45° (there, the difference is huge). But how you presented it, 100% would mean a vertical climb at 90°. In fact, a correct way to say it would be something more like "4% is climbing 4 inches in 100 inches of projected track on the plan or 100 inches of horizontal move", I don't really know in proper English, sorry. And in fact, it's what you later actually do on your example plan, which is then totally right for this. :) The second one in my opinion, even if I am not 100% sure of it, I think is that the locos have less traction in the curves not because they have less surface of contact on the track but, on the contrary, because there si too much contact, and therefore too much friction, because of the oversized wheel flanges we have on scale models and that are rubbing more on the rails. Not mentioning also that the coaches are overweighted compared to the loco, which does not help in slopes, but that's too long to explain. Again, I did not want to sound annoying or too picky and I love your channel and you (even if you hide skelettons a bit everywhere) !!! :) And by the way, please correct me if I am wrong in what I wrote (beside my broken English, of course). Have a nice day ! Cheers ! :) :) :)
This kind of nitpicking is exactly what I'm on CZcams for. Thanks for keeping me honest. But the mathematical differences are so small that none of what you mentioned would make any difference at all on a model. If anyone is coming to my channel for real world engineering advice, then they probably made a wrong turn at Albuquerque.
@rMesaStudio Thank you Dave for this answer which really honors you ! Keep being honest and nice as you currently seem to be ! :) Of course, I totally agree with you about the fact that it does not make any difference on any model (unless we imagine a crazy rack railway :D ). That said, you might be surprised where "real engineers" can sometimes get their inspiration from. ;) Happy modeling ! :)