John Armstrong's original design assumes two basic grades : 3.6% on the steep side (shown above the middle scenery backdrop in my layout design) and 2.1% on the lower side. Since I planned to use Woodland Scenics foam grades, I had to rework the grades to be multiple of 1% (actually more like 1.04% - more about that later) although the overall effect is the same with regard to the maximum height reached in the layout. The steeper side primary uses a combination of 3% and 4% grade packs to reach the ultimate 5.5" elevation. The lower side relies mostly on 2% and 3% grade packs. Finally, I've worked in gradual grades changes, i.e. working through 1%, 2%, etc., both in the up and down directions with a minimum of 55 scale feet (3 inches on the layout) per transitional grade section.