Question about 4% grade

It depends on your traction. For mainline diesel or steam, use no more than a 1 percent grade, and for branch lines keep it below 3 percent (the lower the better) - 3 percent will be a struggle for steam. Electric trains can handle steeper climbs and some systems have 6 percent grades.
The steepest grade east of the Mississippi River in the U.S. is Saluda Grade in western North Carolina - 6 percent. That is steep. Offhand I'd say you should be ok if you stick to grades under 2%.



77Railer
Courtesy of Gary's Trainz Pages
 
Model railroaders tend to use steeper grades than prototype, just as they use sharper curves. Since we have shorter trains, we get away with it.
The logging fans use extremely steep grades.
You might want to test a typical train. Put track along an 8 foot straight plank (2x4 or such). Raise one end an inch and see how the train likes it. Raise it another inch and test again. Each inch is about 1%. You'll want a very high quality plank for this -- no dips or twists.
 
The accepted max has been 2% max. grade for as long as I can remember. Loggers/miners/narrow gaugers will run 6 or 7% because their locos are geared different and the loads are smaller. But get a mainline consist of 3 powered units and 50 cars on a 2% grade and watch it slow down or stop altogether. Forget 3% or 4% unless you are willing to live with 3 power units pulling 15 or so cars. David has the best suggestion, try it and see for yourself before you mess up your layout. Same with tight curves, S curves, and snap switch turnouts. Don't kid yourself by saying "yeah, I know, but I can live with 15 inch radius curves on a 6% grade witha a snapswitch at the top into an S curve. " :D Fred
 
dash10 said:
Don't kid yourself by saying "yeah, I know, but I can live with 15 inch radius curves on a 6% grade witha a snapswitch at the top into an S curve. " :D Fred
Click to expand...
Hmm..sounds like someones speaking from expirience. :p
 
dash10,
i can pull an eleven car train with my cheap arnold sw1500 cow up a 3% grade. do not yet own enough rolling stock to make it spin.

my kato e8/9 makes the same pull at slooooooow speed. crank it up and it's like there is no incline.

respectfully

david
 
I have between 2.08% and 2.4% grade on my Laggan Sub layout,(the same grade as the real Laggan Sub.) and that grade is about 120 feet long. I run 40-50 car trains with 3-4 locomotives on them, and the tightest curve is 24" raius. 2 Kato SD90's will pull a 40 car unit grain train with no problem, I actually have 1 in the front and 1 in the middle. If I use SD40-2's, I'll need 3 for the same train.
 
My steepest grade is 6 feet of 2.77% on the foothills sub.. My longest grade is 36'9" of 1.91% grade.on the mountain sub.
 
Dwight,

There are, essentially, two rules of thumb. The first one, articulated by 77Railer, is essentially what the prototypes aim to achieve. The second is "use whatever grade you want, as long as it meets your needs." If you need to boost a train 2" in 4', then do it. You'll need more locos to pull it, and some locos may not make it at all, but if your trackplan and space requirements demand a 4% grade, go for it. Real railroads generally deal with a different set of physical and economic limitations than model railroads. Generally, laying track through tunnels and winding up canyons costs real railroads a lot more than laying it across flat plains. For us, not much more. Operating trains up steep grades costs real railroads a lot more, not so with us. Conversely, buying right of way X as opposed to Y doesn't cost a railroad much more, whereas for us to expand the amount of space we have available (thus reducing the gradient needed) can be prohibitively expensive, and that's just the economic cost.

So, while there are certain limitations imposed by physics (don't expect your loco to go up a 30% grade), those are the only one's set in stone. Fortunately, it doesn't cost us any money to determine the grade limitations of any given loco, unlike the prototypes, so you can experiment. All other aspects of the "rules of thumb" are flexible.
 
Canadian Pacific had a really fierce grade in the Rockies, which was called the Big Hill. I think it was over 4%. Besides having to triple-head trains going up the hill, there was a major problem with runaways going down the hill.
The hill was replaced by the famous Spiral Tunnels, and the grade is now used by the Trans Canada Highway (where all the units are over-engined).
 
Guys, I know this is an old thread, but rather than start a new one, I did a forum search for gradient & this was the newest LOL.

This is the first time I've ever worked with gradients, and I've been doing a lot of head scratching. So for my own peace of mind I just wanted to know if I am right in my calculations here?

1" rise in 100" = 1%
1" rise in 50" = 2%
1" rise in 25" = 3%
1" rise in 12.5" is 4%
1" in 6.25" is 5%

Is that right or have I made a total pigs ear of it? :D

Edit: Or is there a simple formula such as Height divided by Length = ??%
 
webmaster said:
Guys, I know this is an old thread, but rather than start a new one, I did a forum search for gradient & this was the newest LOL.

This is the first time I've ever worked with gradients, and I've been doing a lot of head scratching. So for my own peace of mind I just wanted to know if I am right in my calculations here?

1" rise in 100" = 1%
1" rise in 50" = 2%
1" rise in 25" = 3%
1" rise in 12.5" is 4%
1" in 6.25" is 5%

Is that right or have I made a total pigs ear of it? :D

Edit: Or is there a simple formula such as Height divided by Length = ??%
Click to expand...
You were doing fine until you reached 25", which should be 4% with a 1" rise. 1" in 12.5" is 8%. You have the forumla correct. Divide the rise by the run and you get the incline or grade in percent.
 
On the aforementioned 6% grade, the railroad (N&W I think) was required by the state to have empty hoppers spaced throughout the train of loaded hoppers for additional braking power while descending the mountain. If you want to (or need to) model a similar steep grade, then you also could intersperse empties with the loads for the descent, and also use helper locos for the ascent. If the real (prototype) railroads did it, you can too. The extra operations involved with the setup could prove enjoyable.
For your math problems, first figure out the rise in 100", 1"=1%, 2"=2%, 6"=6%, THEN extrapolate it to the total length you are considering. Are you considering the grades for overpasses and underpasses, or just for mountain scenery? It makes a huge difference wether you just want it or really need it to have enough headroom for the train passing below.
 
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