Inclines

[coopiedog]

Hi all. I built me a truss bridge that is 11 inches high. To get down to ground level from there I have read that I need a 4 degree incline. From 11 inches at 4 degrees, it's roughly 9 1/2 feet. That will put me around one full turn. Will my trains climb that on a turn or do I need to adjust it any. I haven't built the incline yet and would like to know of any alterations I need to make before I do. I run dc and dcc trains on this rail. Any input would be helpful. Thanks.

[jward]

grades are measure in percentages, not degrees. 9 1/2 feet  is 114 inches run. rising 11 inches in that run is about a 10% grade, far too steep for your locomotives to pull trains on. at the practical maximum 4% grade, you'll need 275" of run. that's 23 feet.

[coopiedog]

Dang, 4% is a whole different animal. I will have to rethink my layout. Maybe add a spiral switchback or set my truss bridge down in a valley lower than ground level. Hmmm. thanks man.

[rogertra]

Or, you could use the easier to understand UK method, the one in something method.

4% = 1 in 25; 2% = 1 in 50; 1% = 1 in 100.  Doesn't matter what the units are, providing they're the same for the one and the length. 

[Doneldon]

Coop-

As others have said, your 10% grade is far too steep, even for a ramshackle logging or mining railroad, unless you use geared steam and even then such grades will be a challenge for your motive power. To answer your other question, yes, curves have the effect of making grades "steeper."

There is more friction between the wheel flanges and the insides of the railheads on curves than on straightaways because that is a sliding action, not the efficient steel rolling on steel. (Well, brass rolling on nickel-silver, but you get the point.) Curves have less of an effect than grades but it is a real phenomenon. Just think of model trains running at constant power on a level oval of track; you can hear and sometimes see them slow on the end curves. Sharp curves result in more friction and will impede your locomotives more than gentle curves. Using a 10% grade with the typically sharp curves of model railroads will reduce most locomotives to needing helpers to get themselves up the hill! That's not literally true, of course, but it's not far off of the mark.

We usually don't mention it here but grades and curves cause other problems, too. For example, there is always a point where a tangent (straight) track begins to curve. That is true for horizontal curves on the level (or a change in degree of curvature) and vertical curves (or a change in the degree of grade). It even occurs as a train exits a curve (except the top of a grade). You might envision the effect as a train stubbing its toe every time the train changes direction. And it's true for every wheel on a train, even the second wheel of a two-wheel truck. The effect is greatest for every "first" wheel of a given set of wheels held in the same straight line (trucks, steam engine drivers, etc.), but every wheel will bump at least a little.

We can easily minimize the abrupt change in direction with so-called transition curves which are progressive spiral curves, or at least more gentle curves, at the point that our track changes direction. It is impossible to remove all effects of curvature changes, even on the real rail lines, but the effects can be significantly mitigated through the use of transitions.

It's harder to ameliorate the effect of toe stubbing on vertical curves. This is especially true for sectional track with roadbed attached. Such track doesn't bend in the middle so any change in gradient results in a sudden bump. And those bumps can cause both derailments and coupler problems unless everything is within spec. Beginning a vertical curve in the middle of a piece of flex track is the only way I know to attenuate the bump on vertical curves. I suppose non-roadbed sectional track could be tightly spiked so a grade begins somewhere other than at the rail joint but it would be harder to accomplish this.

So ... it can be fairly said that curves and grades exist to bedevil locomotives and the people who operate them, whether model locomotives or the twelve-inches-to-the-foot variety. Our job as civil engineers is to reduce these problems to the greatest degree practicable so the operating engineers (also us) can move their trains over the rails.
                                                                                                                                                                                               -- D

[Br 98.75]

We go by a max of 1 in for every foot, at my club. so over one foot it will rise one inch.

[jward]

that's still about an 8% grade. try cutting that in half, or ever 1 inch per yar, and you'll have much better results.

according to a table published in one of the atlas plan books, a locomotive will haul 16% of what it will pull on the level, up a 4% grade. that's 1 car upgrade for ever 6 on the level. beyond 4% the pulling power rapidly diminishes to the point the locomotive can no longer pull itself uphill.

[Br 98.75]

Yeah its mostly on one spot our layout was modular but we anchored it. our bridge is a inclined tressel and it probably rises about 15 inches in 25 feet

[Doneldon]

Yeah its mostly on one spot our layout was modular but we anchored it. our bridge is a inclined tressel and it probably rises about 15 inches in 25 feet

Br-

Fifteen inches in 25 feet is a 5% grade. That's way too steep for anything other than mining or lumber lines. Such a railroad would likely be narrow gauge and probably use geared locomotives.
                                                                                       -- D

[rogertra]

Yeah its mostly on one spot our layout was modular but we anchored it. our bridge is a inclined tressel and it probably rises about 15 inches in 25 feet

Br-

Fifteen inches in 25 feet is a 5% grade. That's way too steep for anything other than mining or lumber lines. Such a railroad would likely be narrow gauge and probably use geared locomotives.
                                                                                       -- D

For most "scale" model railroads, the model railroads seen in the major hobby publications, for reliable operation 2% is considered the steepest grade with 3% at a pinch.

[Br 98.75]

http://www.youtube.com/watch?v=SleK1GqaYOc 
the rise starts at about  4 feet back from 2:06 and you can see the difference between the levels at 2:39  the tressel alone rises 2 inches in about 2 feet at 2:46 i didn't have a say it is over 30 years old i'm not arguing that it is to steep i'm just saying it what we have and i can pull 6 coaches with out a problem.

[electrical whiz kid]

I have a suggestion for what it is worth; and this would apply more, I guess, to layouts built on an "L"-girder system.  If you like, think about cutting out that part of the layout you would like the trestle to reside in, put in a piece of plywood, reinforce it really well, and then build your trestle.  You will eliminate two problems:  1: the scenery problem, and 2: the tractive one.  With the same track distance, you could reduce your percentage to roughly 3-4%; far better than what you were facing.
Rich C.

[electrical whiz kid]

Addendum:  Roger Travis has a pretty valid point.  You may want to really research the issue further and go with some good practice.

RIch C.