I have 35 foot run that needs to rise to 18 inches, I need to know is 4.5% +/- too much for a run 35 feet with curves. Basicly I have a center island that I want to build. I will have a 28" rad. half circle as part of the hill. reason I ask this is because I have had problems in the past with Double Stack cars tipping when I have 70+ cars on a train. Any insights would help me especially from people that own large size layouts. Thank you to all that reply.
Ross
Spokane, WA
Hello Ross,
Sounds risky to me. Short trains of, say, eight 40-foot cars or less would fare OK with that steep grade and degree of curvature, but longer trains, especially longer cars, will probably find it tough to negotiate.
I’d consider reducing the grade by increasing the run, maybe by adding a helix to gain elevation, or rethink my layout design and what it was I was trying to accomplish. Part of good layout design is to make the design accommodate the trains, not the trains accommodating the design. The latter seldom works well, and it sounds to me as if that might be occurring here.
Helixes can be difficult to construct, I know from personal experience, but if you have the room I believe you’ll find it better in the long run, so to speak, for the elevation gain you’re seeking. By keeping the helix gradient to 2.5 percent, which is reasonable, you can use a 28-inch radius to gain 4.4 inches per turn. Four turns of the helix will give you 17.6 inches elevation with a much gentler grade.
Regards,
Paul Schmidt
Contributing Editor
Trains.com
Ellensburg, Wash.
Paul was being polite when he said it was risky. If you want good smooth operations you will find another way as Paul suggested.
Too steep and too sharp for long trains. The other thing is to be sure that you have overhead clearance and side to side on curves for your doublestacks, but you know that already. 
Roger
I would agree that this is too steep. On the other hand a grade of say 3 1/2% would be ok if you are modeling a helper district and plan on double heading and keeping the trains short.
Bruce
Paul, Do you think if it was a 3% grade with the 28" curve, would that work. I am trying to save a yard but if I have to I may be able to move it to the upper level. My wife has decided to move her N scale layout upstairs so I have more room to expand and am seriously thinking of adding a second level to my layout. If its still too steep, tell me what the minimum % I should use. I don’t think I want to use a helix cause it will be in the center of the room. Thanks a million,
Ross Waters
Spokane, WA
Hello Ross,
Three percent seems much more do-able to me, especially with a 28" radius. I’d be inclined myself to call that a reasonable solution. And a helix in the center of the room, good to avoid that. They’re not pretty.
If you ever get to Ellensburg drop by. My e-mail is schmidtcp@elltel.net. I’d like to show you my layout.
Paul
If you had well matched mid-train helpers - like BNSF and UP use climbing out the Snake River - you would have a better chance. Real trains use mid-train helper for the same reason.
Nigel
Hello Nigel,
Not to be argumentive, but BNSF doesn’t have any mainline trackage along the Snake River. UP does use DPU mid-train helpers over the Blue Mountains and in parts of Idaho.
Regards,
Paul Schmidt