Acceptable grades

RetiredFF Jun 17, 2013

  1. RetiredFF

    RetiredFF TrainBoard Member

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    I am in the process of designing my HO layout. My question is about acceptable grade on an elevation. I want to reach the highest elevation I can with a track length of approximately 40'. It seems depending on who you ask it is permissible to go as high as 4%. I can attain a max. height of almost 6" at a rate of 3.5%. I plan on running short trains on a NCE DCC system. Is this too much? I am confused because some companies sell ready made risers to 4% grade. Looking forward to some input on this.
     
  2. bnsf971

    bnsf971 TrainBoard Member

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    4% is a pretty stiff grade. Count on ten car trains, with either a large SD type or a pair of Geeps. Any steam under a 4-8-4 would be a 5 car or so train. Curves increase the perceived grade, the tighter the curve the bigger the struggle to the top. The steepest mainline grade in the US is around 5%, and required 2-3 high horsepower diesels to haul 20 cars up it.
     
  3. ScaleCraft

    ScaleCraft TrainBoard Member

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    And that was Saluda, near you, closed and mothballed how many years?
    2% mainline ruling, can vary up to 2.2%, 2.4%, was just cal it 2. Narrow gauge 4%, but again, could be steeper.
    Grade is the same on 1:1 and any models.
    Dave
     
  4. BoxcabE50

    BoxcabE50 HOn30 & N Scales Staff Member TrainBoard Supporter

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    Most modelers try to stay close to 2% as a maximum. Or less if possible. You can certainly go 4%, but usually when done, folks find it has limitations and troubles preferable to avoid. I'd see if there is any possible way to get more length of run than proposed. You would not regret building a lesser grade.
     
  5. Candy_Streeter

    Candy_Streeter TrainBoard Member

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    You did not say why you need such a high elevation after a 40 foot run. Maybe something can be modified
     
  6. RT_Coker

    RT_Coker TrainBoard Supporter

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    I am not recommending a maximum grade! But, I do recommend that you pay special attention to the grade changes if you go with more than 2% grade. I have ~ 3% grades and whish that I had used more gradual grade changes.
    Bob
     
  7. RGW

    RGW TrainBoard Member

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    FF, not sure of the math being used here. Your 6" rise over 480" of run is a grade of 1.25%. Likewise at 4% you would gain over 19" in 40'. Formula is (rise/run)x100=%grade. Also my experience is that only geared locos will look good at that steep of grade. M

    Sent from my GT-N8013 using Tapatalk 4 Beta
     
  8. cajon

    cajon TrainBoard Member

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    The formula for determining grade is rise divided by distance. In your case a 6" rise divided by 480" (40' X 12") is a 1.25% grade. A 3% grade will give a 14.4" rise.
     
  9. cajon

    cajon TrainBoard Member

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    The narrow gauge Uintah Ry had some 7.5% grades w/ 65 degree curves AND ran 2 2-6-6-2s over that! So geared locos aren't always required over 4%!
     
  10. JNXT 7707

    JNXT 7707 TrainBoard Member

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    Since you are asking, I would advise nothing over 2% if you can avoid it....and if you REALLY are set on short trains. As mentioned above, if curves are involved, they make the perceived grade higher.
    I have 0% grade on my layouts and it's interesting how taking a longer train around a long loop will increase the effort on the locos. When you throw a curve in....well, to illustrate, I had my portable layout in the garage. The floor is not 100% level, has a definite grade to it. You could tell by running trains (fairly short trains at that, behind a single loco) when it was climbing a "grade", and heading into turns took it down farther. So this experience alone has made me rethink any long term plans on my next layout to include a grade, and how steep it would be.
     
  11. RGW

    RGW TrainBoard Member

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    Never said required, just discussed aesthetics.
     
  12. COverton

    COverton TrainBoard Member

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    To the OP, when you say 'acceptable', do you mean that most of us would approve of, or that most of us have been forced to accept, or what the grade looks like in terms of realism, or how well the grade works with the locos in the space available? I am not trying to be coy or facetious...but I do strongly maintain that the final arbiter of what is acceptable is a firm tug of war between the loco(s) that have to lift the trailing cars up the grade and their owner....you....the Big Cheese of the Layout. If you are not happy with what works, you'll have to figure out another track plan or get more room. If the loco isn't happy with what you lay for a rail system and getting the trailing 'tonnage' you want it to move up the grade....need I say more?

    Somewhere in the middle ground, you, the Brains, have to reconcile what you want your loco to be able to do with your track system with what the loco SAYS IT CAN DO. If you can manage it, at some point you will be reasonably happy with a compromise or a different solution and you'll find that the loco(s) can handle the newer plan. The fact is the loco can only do so much. Almost any scale loco will climb a 12% grade, but it won't be towing anything else, and even then there'll be a bit of slipping probably. That would be true for all but specialty locomotives in the real world as well. When the Cumberland & Wheeling Rwy set as their standard grade one of 2.2%, Congress approved of their plan and that became the de facto standard for all grades in N. America, including in Canada when American locating engineers were hired a few years later to survey reasonable lines westward across the prairies and beyond. Yes, there are hundreds of grades less steep and more steep scattered across both countries, but the standard was set and railroads looking for financing, either public or private, had better adhere to that standard maximum grade. It works really well on our scale layouts as well, as I have learned. My last layout had 3.3% grades and I had trouble getting my passenger trains with only four Walthers heavyweights and a reefer up them behind a heavy BLI S1b Niagara 4-8-4. I could fool myself into thinking it would work, but I couldn't fool my motive power.

    So, if you have some pretty tough constraints, best to mock it up somehow and do trials to see what your locos can handle. With that more empirical research, it will work on a well-laid track plan as well.
     
  13. RetiredFF

    RetiredFF TrainBoard Member

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    Once again some great information. Thank you all. I guess I was wanting more elevation just for the look of it as it went into a hilly area, but I can very easily stay with a 2% grade. Thanks again everyone.
     
  14. JPIII

    JPIII TrainBoard Member

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    The previous posters know more about conventional main line grades than I, but when one gets to logging & mining, all bets are off.

    On my logging RR, I went to switchbacks up to 4% to get a rise of around 14 inches. With short trains, geared locos make those in a walk. Prototypically, 15% grades were not unheard of.......assisted Inclines up to 78%. In retrospect, I could have made the climb in 5 feet rather than 60 odd.
     
  15. montanan

    montanan TrainBoard Member

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    Even running short trains, this would be a steep grade. I have a short grade of two and a half percent and that can present problems. My layout was built for switching and with this grade it limits my train length to about 14 cars, which is also the capacity of passing sidings along the main line. Any thing longer requires helpers (on purpose) but for looks, a grade much steeper may look awkward. I have a short logging spur with a grade close to four percent and it does look strange, but train lengths are short, two to three cars with a shay doing the work. Even a small diesel switcher can have a hard time on that grade with only a few cars. You may want to find a way to compromise and see if you can tweak the track plan to keep the grade at around 2 percent.
     
  16. gjslsffan

    gjslsffan Staff Member

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    The pics show the train on a ruling 2% grade. I did this because I wanted folks to able to walk into the center of the MRR without having to get on their hands and knees every time anyone entered the MRR barn. The RR starts at 54" elevation and ends up at its highest at 74". had to build elevated walkways around some of the MRR to be able to see, scenic and use it :):). We typically pull 50, (50-60ft) car modern trains. and up to 65 (36-50ft) car vintage trains. It can be done with reliability we rarely have string-line events. The curves are 48" min radius with most at 56" and a few at 72" radius. All cars weigh at least 2 times NMRA specs have Intermountain or reboxx type metal wheels, as well as KD metal draw-bar couplers. Strict adherence to the trusty KD coupler height is observed with any more then .010 off, "Bad Ordered" and removed from service. We run up to 5-6 SD's on these trains, and some get rear helpers on loaded unit trains. You would be amazed what these little engines will pull, it never ceased to impress me.
    I am just saying this to show it can be done with reliability and without wrecking stuff. I wanted a big Mountain MRR with heavy grades and long trains once in my life. Now that it is built, not sure I would do it again this big and complicated. I enjoy the grades and all the challenges it comes with. This is just a lot for one guy to build on his own. I have to say that the Smaller one room type MRR's I have built in the past were very enjoyable for me. Wish I had taken more pictures along the way.
    So if you ever find yourself in Western Colorado, I welcome folks to bring their engines over for a workout, but you gotta have clean in gauge wheels, metal draw-bars at the right height, and bring more than you think you will need, cause you will need them :):).
    Kind Regards.


    PICT0055.jpg Showing the Lynn crossovers with wood lying on it, the right part of the pic shows the upper sta.jpg
     
  17. BarstowRick

    BarstowRick TrainBoard Supporter

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    Maximum grade? A 2% gradient is the maximum I would recommend. That is 1/4 inch rise for each linear foot.

    On the W&A division of the H&P RR, I have some grades, in my coal district that approached 2.7%, recently cut back to 2.5%. On said grade, to pull a 20 car train it took 3 diseasels to lift the train up the hill. Too much power for such a short train. But that's another story for another time and place.

    Typically, 1 of my six axle jobs will pull 10 to 12 freight cars up my two percent grades. Lengthening the train, 2 of my six axle jobs will pull 20 to 24 car trains up my 2% grades.

    I have a rule of thumb that we operate by: NO.... locomotive is allowed on the railroad unless it can pull a minimum of 10 cars up my 2% grades. I've made some exceptions but that would be for a 2 or 3 car commuter or a short passenger train.

    FYI, We tested a single FVM six axle job, on my grades and it pulled 15 freight cars up the 2% grades. Excellent performance! Later we hooked up a 46 car freight train to three FVM six axle jobs and they pulled the train up the 2% grades as if to say, "What took you.... so long to notice?"

    Want to impress me. It's not what a locomotive can pull on the flat, it's what a locomotive can pull up a 2% grade.

    A grade steeper then 2% is a waist of time to the installer and owner of a model railroad. :rolleyes:
     
  18. Mike VE2TRV

    Mike VE2TRV TrainBoard Member

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    I did a test a couple of years ago. I nailed some track to a standard 2x4 (96" long, close enough to 100), and raised one end four inches, making it just about a 4% grade. I then tested each of my locos with three hoppers filled with pennies - since each contained about a dollar, that's about a pound each... three pounds in all!. The switchers I had at the time didn't make it (though I must try it again with the Atlas and Kato switchers I bought later), but all the other engines, with few exceptions, managed to pull that load up the 4% grade. Generally the heaviest did the best, like the Proto cab units which are literally filled with metal. That gave me a pretty good idea of the capacities of locomotives and what characteristics favored pulling power. Nice, empirical data.

    So what do I think about maximum grades? If you have the room for 2%, fine. Otherwise it's the length of the run vs. the needed rise that dictate the maximum grade.I wouldn't mind a 4% grade if I really needed it, though I wouldn't send a switcher up that unless it's a very short train.

    Basically, it's up to the modeler.
     
  19. Dave Jones

    Dave Jones TrainBoard Supporter

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    A rule of thumb I go by is to do what the prototype does. Now, those curve radii ... .
     
  20. JNXT 7707

    JNXT 7707 TrainBoard Member

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    I'd like to see someone do a similar test with curves thrown into the mix. Here the major factors appear to be train length and the weight of the locomotive(s) doing the pulling. There is a certain spot on one end of my large loop where - if a loco is underweighted and the train is long - it's going to start spinning it's wheels.
    So I take the 2% limit with a huge grain of salt - yes, certain locos can make certain grades, but throw a curve into the equation and you have to reformulate in a hurry. Tom's Western Colorado layout sounds like a lot of fun, a huge challenge..and is probably an absolute blast to watch those diesels working. Not sure if I'd want to live with that challenge though! :wideeyes:
    Crandell's advice to mock up something to experience first-hand what your trains will do sounds like the best course of action. That and a good track plan!
     

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