What would be the maximum PRACTICAL gradefor a mainline on a layout? Ours is 23’ x 7’ and has several grades and over/under features. What do you think?
Anything above 3 % is not recommendable.
Unless you specifically design for it. Steep grades = short trains + lots of tractive effort.
My maximum mainline grade is 2.5%, same as my prototype. Hidden track is held below 2%.
OTOH, my mountain climbing shortline has a 4% ruling grade, but it only sees short trains - and even a four car mixed may have two teakettle tank locos on the point and another one pushing.
If you want to run typical North American mainline trains, you really need to hold the grades down. If you build steep grades, expect to need Shays or rack locos to climb them.
Chuck (Modeling Central Japan in September, 1964)
Assuming HO a 4" rise at 2.5% is going to need 160" of length or almost 14’. Add to that a transition area from flat to grade and grade to flat at the top and you will be approaching your 23’ length.
One nice thing about using Woodland Scenics foam risers is you can use them to raise and lower the track. So to achieve a 4" separation you can have one line go up 2", and the other line go down 2". That takes up a lot less space than having one track remain level and another track climb up and over it.
Interesting discussion to say the least.
You won’t mind an old timer chiming here…would you?
2% is the maximum grade I’ve choosen for most of my recent layouts. Oh, I’ve tried the tight radius curves (another issue) and those 2.5%, 3.0% and a 4% grades but I couldn’t get any trains of any significance up those grades. The original HO and N scale " Stoves" aka steam engines, have proven to be the worst pullers…working best on flat layouts. No fun in that. Today’s recent offerings do a tad bit better.
Bottom line…I’d stay with the 2%. Exception being if I’ma modeling a shortline narrow gauge with steeper grades. However, finding a locomotive that will pull three or four cars up anything steeper will take some doing.
I hate to see newbies helping other newbies make the same mistakes. If know what I mean.
The transition areas are key. Going upgrade with a curve is a lot more work. So for modeling using diesels and just tangent track with good transition areas, I have seen 6% to 10% or so work ok for the max middle part of the grade. So, this gives an average grade of about 3% to 5%. Steamers really don’t like much over 2.5% since they’re so light. Also, rolling stock that easily moves is important the more grade you have.
For a helix, I would really prefer a 2% max grade to have a good running railroad. You need enough separation in a helix from turn to turn to accomodate your rolling stock height. So for a helix you need to balance the rolling stock height, vertical separation of curves, grade and curve radii.
Richard
Prototype logging railroads used geared steam to climb grades of 6% and higher. Some here (I can’t remember who at the moment, hope you’ll forgive me) have built logging-themed layouts with 8% grades. Mind you, these are specialty engines pulling trains of no more than 6-8 cars; running these grades with rod steamers or standard diesels would likely be a slippery and frustrating exercise.
Stu
Based on experience, strongly disagree.
hi gentlemen,
John Armstrong stated grades from 4% and more will become an attraction by itself, like doubling the hill, helper service or stalled trains.
Trainlength will be important, however what do you want? For longer trains without helpers your grades might be no steeper then 2%. No engine is alike, some have traction tires, so your question can’t be properly answered.
Keep in mind lots of space is needed for vertical easements. Even more when you allow for space without a change of grade just before or after a turnout.
Curves add friction too, the combination of a grade on a curve can cause derailments and surely will limit trainlength quite a lot.
Smile
Paul
Richard, I don’t agree with your statement quoted above. It isn’t that steamers are so light, it is that their weight is distributed in some cases over trucks that offer no help to the tractive effort, unless those trucks happen(ed) to have a booster engine on them in the prototype.
Many steamers were much heavier than any diesel existing today, but many diesels can pull more tonnage at a low speed on a grade, and lift that tonnage from speed ‘zero’, where any steamer used in N. America could not lift that tonnage. Where diesels carry all their weight over tires that are on driven axles (in most cases), the only steamers that carried all their weight on drivers were the switchers with no trucks on them like the 0-6-0 or 0-8-0 or the 0-10-0 configuration. Those engines were used nearly exclusively in switching service. If the builders needed even a single non-coupled axle under their steamers for weight-bearing or steering control, then part of the suspended weight above the wheels was supported by axles that didn’t contribute to the tractive effort.
In summary, diesels carry more weight on wheels that are driven, so their tractive effort pound for pound is higher, where many steamers had drivers bearing less of their weight and would slip badly trying to lift heavy tonnages or they would stall on hills that a modern diesel could still manage, albeit at a slow speed.
Crandell
My mainline has approximately 8’ of level track, followed by about 18’ in which it climbs approximately 6", then back down approximately 18’ again to the level. Both runs turn twice in their run on 22" radius curves.I figured this to be approximately 3+%? My Athearn Genesis 4-6-6-4 stock (with factory traction tires)is currently lashed up to 20 cars and caboose and pulls well. I have a Bachmann 2-8-0 stock, no traction tires, that will handle about a dozen reefers and caboose. My Bachmann 4-8-4 required an additional 5 1/2 ounces of weight to handle the reefer train, and will at times still slip a bit in one particular spot (though hard on the model loco, I think it adds a bit of realism).
My logging/coal route contains two 8% grades, both on 18" radius curves, handled by a Spectrum Shay. I don’t have enough cars for it, but it has done two skeleton log cars, two 55 ton hoppers, and a bobber caboose well. However, my Shay has been plagued by the cracking and missing driver gears mentioned in other posts, and I have not changed them yet to higher quality replacements.
For what all that’s worth, who knows, but that’s what happens on this particular, as of yet unnamed, railroad![:D]
Duane
Crandell,
I am speaking of models where due to various factors such as wanting visible/accurate clearance between the boiler and trucks. For example, this similar area/clearance in a model diesel can be filled with weight.
This area for modeling really needs to take a lot of things into account. For example if the max grade were 10% for 30 feet and I’m running 50’ of properly weighted hard to roll cars, then many problems will occur.
Since most of us are normally trying to gain 4" or so, then I could be speaking of about a 6’ or less section out of 17’ for a 2% nominal grade. After having built several layouts, the point being–%grades can(and do for prototypes) vary quite a bit to make up an overall average grade. I believe the steepest portion on the Saluda grade(NS-class 1)in NC is 6%. You can have more trouble pulling a long train of long heavy weight passenger cars up a 2% grade with 22" radius curvature with a lightweight steamer than a diesel pulling 6 short coal hoppers up a tangent track with 4% grade.
Richard
Sorry for the second post, but that main with the 4-6-6-4’s consist is 24 cars currently. When I quickly counted for the first
Assuming you are running a “regular” RR - not a narrow gauge and/or logging or mining RR - TWO percent is the maximum I would use. My previous layout used 2 percent to access lower level staging, and it worked out pretty good. For my new layout, I experimented and again came to the conclusion that 2 percent was best.
Even at two percent, it takes two good locos to pull up a decent sized (15-25) car train. That works for my needs. At 2 1/2 percent, three locos struggle with the same train.
Of course if your train size is smaller, then 2 1/2 is not such a big deal. And while there are a couple of instances of mainline grades of that size out in the real world, they are few and far between and helper locos are a must.
Not correct. It was nominally a maximum of 4.7%, with a very short stretch that was rumored to be as high as 5%. In any case, that was the extreme exception and most of the grade was compensated in the curves. Because of the many operating challenges of this grade, it’s been abandoned for a decade or so.
I’ve never seen the 10% grade you recommended earlier work reliably on a model railroad. Why give the newcomers bad advice?
Especially in the model situation, many grades are on curves and the added friction creates a much steeper effective grade.
I have to concur.
Building a logging railroad myself, and observing many very small layouts, I have found that the maximum successful grade has been 8%. And that is only successful with specific model locomotives in HO and HOn3, hauling a max of 3 cars, on very carefull laid track. Many model locomotives can barely haul themselves up an 8% grade, and the bigger ones will be the most likely to fail on the grade transitions because of their length and/or rigid wheel bases.
The most capable common HO locomotive I have seen is an unmodified Roundhouse Climax or its shared drive with the Roundhouse Boxcab Diesel. These are quite heavy, and have a high reduction, flexible drive with fairly short wheelbase trucks not mounted too far apart. But they are noisy!
For general purposes, a 3% to 4% grade will severely limit train length. Hence, the rule of thumb 2% maximum.
just my experiences
Fred W
Like most modellers, my around-the-room layout has many curves, and because it was built with the intention of eventually double-decking part of it, the grades are mostly around 2.5%. (the area in grey will eventually be covered by a second level, the access to which will be from South Cayuga around the peninsula.
Because most of the grades occur on curves, with some of them being reverse curves, the effect of the grade is increased. The table below shows this effect. (I don’t recall where I found this information, but if anyone can point me to its source, I’ll gladly include the proper accreditation.)
To calculate the effect of curvature upon grades, add 0.05% for every degree of curvature to the actual physical grade already present.
For example, a 33” radius is approximately equal to a 25 degree curve. 25x0.05% =1.25% would be the compensation required for the curve and would be added to the actual grade. A 2.5% grade on a 33” radius curve would therefore be equal to a 3.75% grade on straight track.
Below are approximate equivalents, in degrees, for the given radii. Using 33”=25.1 degrees* as the starting point, reduce or increase respectively the number of degrees by 0.76 as the radius increases or decreases.
NOTE: The further away a radius is from the known 33” radius, the greater the inaccuracy of the table.
To calculate the percentage of compensation to be added to the physical (actual) grade, multiply number of degrees by .05. (* represents known value - all others are unverified assumptions)
RADIUS
24” - 3
What kind of railroad does have a huge effect on whats acceptable for grades, and in some cases which prototype you follow does as well.
In my case I’m actually planning a couple long (2 or 3 train lengths) 4% grades to trabnsition from one level to the next. Many short grades (one train length) will be near 3% but most others will be 2% or less. Most trains will be 10-12 cars with a couple 4 axle diesels on the point. But I’ll also be running some ore and coal drags of about 30 hoppers. The drags will be powered by a couple C628’s and an extra 4 axle on the point, my 4% grades are helper districts so another loco or 2 as pushers.
In my case it’s agreat excuse to run more locos, yes it can be pricy but it’s what I want. And it’s also quite prototypical for my plan. Real railroads did this kind of stuff all the time, if you can’t conqure the grade add more power or run shorter trains.