Reply to "O Scale Track Grades"

I had a Sunset B&O T3 (2 rail) running on a 2% or less grade but 6 walthers passenger cars caused it to slip.  I added weigh to the boiler and then we made it to the top.  6 walthers cars with walthers trucks is pretty heavy.  Heavy engines and light trains are big variables but  4% is pretty steep for most engines.  I am building a new layout and have a long 1.5% grade along two walls.   But even with that, I kept the curve portion in the middle of the grade level.