5.5% Grade, testing pulling power!
Many people think the Tenessee Pass at 10,248 ft is the highest route the D&RGW had over the Rockies. In fact, Marshall Pass (part of the Royal Gorge Route) crossed over the Rockies at 10,846 feet. While Marshall Pass was mainline, it had a few drawbacks coming into the 50s that caused the D&RGW to abandon the line around Mile Marker 220. First, it was still Narrow Gauge, and second, it had a significant amount of 4% trackage on both sides of the mountain.
Breaking the rules
Rules are “guidelines” and are meant to be broken. But one is not allowed to break the rules unless one knows the rule and what the rule’s intent is.
As far back as I can remember (mid-90s), the NMRA has always recommended a 2% grade and cautioned not to exceed 3%. I found recommendations in two magazines from the 50s stating 2% is the max.
With N-Scale, it’s difficult to get that “Big Mountain” look in a small room with a 2% grade, and I want more of a dramatic scene and the challenges that comes with a 4% grade. My back wall is 10 feet across, and by the “rule,” that’s only a 2-inch rise – blah! Unraveled, my mountain section is 475 inches long (39.5ft / 6,334 scale ft) and currently averages 3.2% with a 3.4% ruling grade. But I still want more!
So this weekend, I set out to see how much I can realistically get out of my weakest locomotives. I have a pair of steam engines, so I started with one. Then my older Atlas GP30, which had to have the frame milled to get a decoder installed, as well as my smallest switcher. I set up a ramp with some Kato track, settled in on a 5.5% grade, and loaded them up with some rolling stock. Here are the results.
Side note: Being new to N-Scale, I have been using some old Kato track I bought used online. This makes testing various designs, curves, and grades very simple.
A few comments about the test track grade. The effective grade is different than the 5.5% shown on the indicator because (1) the track length is longer up the grade account of the curves which lessens the grade and (2) the curves introduce a grade increase due to the curves depending on the radius of the curves. On a full-sized railroad, a curve adds 0.04% grade per degree of curve which is directly proportional to the radius{ sin 1/2 D = 50/R} This is the chord definition of degree of curve or “railroad” definition. Highway departments usually use the arc definition of D:100 = 360*: 2 pi R. On the ground, the two definitions will lay out almost the same up to 3* but the chord definition is the easiest to calculate and lay out. I am not nocking your test which served your purpose. It was interesting. The passenger train really has 5 cars because of the caboose which needs to be taken into consideration. Happy railroading with your layout.