Acceptable grades

[lajry]

Dividing 10" by 180"(15') gives you an 8.33% grade. So that is a very steep grade. But the narrow gauge Uinta Ry had 7.5% grades w/ 85 degree curves & ran 2-6-6-2s thru that! So it depends on your prototype. Santa Fe's Cajon pass has a 3% grade on one track but mostly runs trains down grade.