I used to have that thin little ABC’s of model railroading book, but can’t find it anymore. I am thinking about adding a switch with one track going to a lower elevation and a dead end w/mirror that is a servicing track for a power plant and the other to go up and cross over the lower grade.
What is the rule of thumb for grades? Is it like 1" in elevation to 1’ in distance for HO?
Grades in the US are expressed in per cent. That is the number of units of rise in 100 units of run. So a rise of 1" in 100" would be 1% grade. Typically model railroad grades run the 2% range where trains have to operate. On industrial spurs and connecting tracks you can get up to 4% but it will affect the performance of trains significantly. 1 inch rise per foot is about 8% grade, way way too steep except for an industrial spur to a coal trestle where the engine will only be handling 1 or 2 cars. The steeper the grade the more of a “transition” you need at the top and bottom of the grade to ease back into level track. If the transition is too sharp engine pilots and pilot sheets will hit the tops of the rails, fuel tanks on long engines may be high centered, and cars may uncouple. If you want a real steep grade I would suggest mocking it up first to see how it will work.
I agree, Dave. And your key point for someone who is thinking of attemting his first grade, apart from the really good advice to mock it up on a counter or table and see how the engine(s) do on it, is that as you build more of that vertical curve that eases both into…and out of…the true grade, you unfortunately eat up a lot of space. Now you have even less to accomplish the change of elevation that the main part of the grade has left in which to do it! So, the conclusion one should arrive to is…ease up on the grades. Ease up on your plans to have a difference in elevation. Or, find more length to accomplish that really necesseary change in altitude.
But you can’t have a short run horizontally to get several inches in height, and still have room for those all important curves at each end. Something’s gotta give.
-Crandell
I was going to try to create a distance in elevation of about 3" to 4" in a span of 8 to 9 feet. My thoughts were to take the main line up in elevation of 2" in the 8 to 9 feet and then take the spur down in elevation 1 1/2" to 2" in that same amount of space. Maybe I will just have to wait until I have more space for this idea to pan out.
Rob
waiting is an excellent idea. Your grade would need a transition at the bottom and top of both grades and more than likely a level section at the top. this would eat up a lot of your 8-9 feet, leaving very little for the grade…
I don’t have a clear picture of what you described above, but rising 2-3" in 8 or 9 feet is quite reasonable. You could even have your transitions and need the main steady grade to be near 3%, which isn’t shocking on a model railroad. Of course, it depends on what you have in mind for the top end of it. Do you have room for an industrial track and a small runaround track? What engine doing what kind of work…how many cars?
But if you only have the sum of 8-9’ for everything, and still want 2" of height and a level ‘landing’ up top for the industry…yeah, you’ll need about 4.5-5% grade for that, and that is very steep and demanding for all but tank engines or geared engines.
-Crandell
Aaaahhh … tank engines
Aah, yes…#7’s the only steamer in which I have ridden in the cab. I have a couple of paintings by one of her hoggers, too. Thanks, Mark.
-Crandell
Lucky you, Crandell. When there, I was fortunate to have a short ride in a 1940s logging truck.
Test, Test, Test!
I just learned this while building my layout. Take the longest train that you plan to run and take the weakest engine you plan to run in front of that train and test the train on the proposed grade. Make sure all of your rolling stock is at the appropriate weight too. You might be surprised what grade you can actually run.
3" rise in 9’.
(3"/(12x9’)) x 100 = 2.78% grade
