Hi!
I’m Tomcurt and new to this design stuff.
Can anyone tell me what the maximum grade allowable is. 4%, 5% ??
Hope you can help me.
Welcome, Tom. I hope you turn to us often for help.
Realistically, around 4-5% is the most you will want on a typical trackplan, unless you are meaning to model a logging or mining track. In that instance, you would want geared locomotives like the Shays, tankers, Heislers, and such. They could take grades that would make us sweat just walking them!
However, in order to keep your enjoyment and costs down, your main level lines should not exceed 2.5%. I say this because as you add towed weight to the loco, any curves and grade brings you closer to spin-out. You would then need to have another helper loco, and now you are adding cost to the layout.
Keep your grades under 3% if you want your trains of modest length to do well on them.
Selector is right, grades steeper than 2% require a LOT of planning and forethought and will impose severe operating restrictions on you.
The prototype I’m modelling carried sustained five percent grades, and that’s what I used. A Spectrum can haul exactly two boxcars up it, not even a caboose, and even then the drivers skate and the loco grunts and groans a bit. That’s not a problem for me, because that’s what the prototypes could do, in fact, it helps me to understand the restrictions the steep grade put on the real railroad back then. Instead of long trains, they had to run a lot of short ones, four, three, even two cars at once, cabooses were a luxury too expensive to be generally used, in terms of weight.
A Lifelike (trainset quality) GP38-2 can haul maybe ten cars up it, MUed, a pair can haul at least 15. A P2k GP38 can haul a lot more up the grade, more than I’ve tried, but it requires more than 50% throttle just to move at normal operating speeds because it is so heavy.
A Bachman Shay will pull about five cars up it, but it has all wheel drive and is still pretty slow. Some people here report better performance from Shays, but I guess my wheels are slicker or something, because five is all I get before the loco stops with the wheels spinning away.
Steep grades require multiple locomotives, or very heavy singles, lighter than NMRA cars, and short trains, and putting a grade on a curve will make the locomotives work even harder.
The steepest grade ever on a normal railroad was a 7% sustained grade, in Evansville, Indiana of all places. The locomotives had to be specially rebuilt, with blocks under one end of the boiler so all the water didn’t run to one end. Cog railways and some other esoteric types used steeper grades, but that’s not for normal layouts.
Don’t forget to add in some horizontal space for transitions at the top and bottom of your grade. Going from 5% to dead flat instantaneausly will cause derailments and stalls bec
Jeffers_mz, I read a formula somewhere but I can’t remember it (getting too old). It was the length (or distance) and the inches of rise. Like over 8’ you can go up from 0" to 4", something like that - can you expand on that formula for HO inclines?
Thanks …
A two percent grade which is the maximum I use only when absolutely necessary is 2 inches of rise every 100 inches. Nominally eight feet. I usually work to 1 inches per 50 inches. Any steeper and all of those problems explained above will happen and more. Engines need to be properly weighted even for 2 percent grades. If an an engine can pull 15 car passenger trains on the level, I don’t want a grade that will not permit that same car length. Otherwise, all of your trains are limited in length by the amount that can be pulled up the grades on your layout.
The formula is the same for all inclines, regardless of where they are. Commonly, it is phrased as “rise over run.” You take the linear height and divide it by the run, or the length horizontally that is to be covered. The resulting figure will be a decimal if you don’t mix units of length. Move the decimal point to the right 2 places, and read that number as your gradient in percentage.
Most of the problems the majority of modelers have is lack of space.
I fall into this catagory.
The smaller the layout room, the steeper the grades.
Three out of four grades I have on my layout is at least 3.5%.
The fourth is about 1.5%.
I don’t have a lot of room on a 9x12 HO scale layout for long trains so I’m able to get away with having to use a short train, max 10 cars for the sidings I have.
Things like this is something you might want to consider when you plan your track plan.
Gordon
Gordon
You’ve hit on something that is generally not given enough thought in most track plans I have seen. Length of train. The length of trains one intends to run on the layout really should dictate almost every aspect of the track plan. Curve radius/turnout size is about the only area that is indirect instead of direct. I say indirect because the length of train also tends to size the locomotives which in turn impacts minimum radius/turnout size to some extent.
But passing sidings, “town” size, main line between “towns”, yard length and configuration, and yes, grades, are all directly impacted by desired train length. All these elements should be tied to the same expected train length, or space is being inefficiently used. Put train length very close to the top of your givens and druthers, and you’ll end up with a better plan.
yours in train length planning
Fred W
Grades on single-track routes are, of necessity, dictated by the upgrade traffic. On double track, the purely downgrade track can be, and frequently is, steeper.
John Armstrong put a short section of 8% grade into one of his track plans. It was intended to be used by locomotives only.
I have a rather longer section of 8% downgrade, which is operated in one direction only, The more or less parallel upgrade track is on a 3% grade.
I have found that allowing 6 inches of transition for each percent of grade keeps my four-axle steam and four powered axle diesel-hydraulics happy. (Yes, the transitions into and out of the 8% are four feet long, and add two feet to the apparent grade at each end.)
For a prototype example, check out the UP line through Weber Canyon in Utah. The upgrade track is much longer, while the downgrade track looks like a toboggan run.
This formula really should be tatooed to everyones $@& ! [:D]:
Rise (height)= % divided by 100 times Length of rise (in inches)
% (grade) = Rise divided by Length (in inches) times 100
Length Of Rise = Rise divided by % times 100
I have this written on a card and stapled to the wall in my layout room.
2% is the accepted maximum norm for mainlines on medium to large layouts(plus or minus .5%)
3% (+/- .5%) would be fine on a smaller layout (4x8). The trains will be shorter.
These percentages also “look” good. 4 and 5% grades start to look like a roller coaster.
I hope this helps.
4 and 5% grades start to look like a roller coaster.
From the side, maybe.
In a jeep, on a shelf wall, after a hundred years of non-maintenence, four hundred feet above the microscopic creek and pines below, switchbacking up a live rock glacier, dinging big rocks off your differentials, feeling her lean when the old grade is too narrow and you have to put two wheels on the upper bank and the other two into the soft stuff over the edge, feeling all four wheels in turn catch and then spin free again, throwing gravel everywhere, “roller coaster” isn’t the term I’d choose. In fact, my choice will trigger the censors here.
Point being, if the prototype used a 5% grade, then the same grade will scale to your layout, and look…prototypical. I like watching my locos grab and slip, working the grade, huffing and puffing , never sure if they’re going to pull it today or not, spewing sand all over the rails trying to cut the odds their way, same as I like topping out in an alpine meadow after a tough climb in the jeep. But the mountains aren’t for everyone, in fact, most people are more comfortable down in the flatlands. To each his own, when it comes to model trains, it’s all good if it makes you feel good.
Tomcurt, since eight feet is close to 100 inches, then a two inch rise in an eight foot run is close to a two percent grade. A four inch rise in eight feet is close to a four percent grade.
Everything depends on the type of railroading you are modeling. If you are modeling a class 1 railroad and want to run long trains, 2% is the max I would go. If you are modeling a shortline that is going to have short trains, you can go more. Steeper grades give you operational challenges but that can be a good thing if you like variety. You can use helpers or double the hill which means you take half your train up the hill at a time. After making the first trip, the engine runs around the front half of the train and comes back down for the second half and then recouples both halves and continues on its way. This was a neccessity on some prototypes although it was a major pain to have to do.
We always like to give you a full baker’s dozen, tomcurt…as you can see. I suppose this would be a good time to impress upon you that, for those who are planning on developing and building a layout, the first step is deciding what you want the layout to be “about.” What era, what prototype, what capabilities or functions will it comprise, and so on. For you to get the most out of your investment in time and money, effort in planning is seldom wasted.
Keep your big trains’ grades under 2.5%, and your slower, shorter, industrial grades to 3.5%.