Closure to "Field Observations and Analysis of the Subgrade Response Beneath GRCS Embankments at the Council Bluffs Interchange System" by Aaron P. Gallant, Ehab Shatnawi, and Danilo Botero-Lopez.

Drag Load and Position of the Neutral Plane The writers agree with the discusser that loads applied to the structural design of controlled-modulus columns are similar to conventional foundations, including downdrag. Applied stress in the foundation soils, and thus depth of the neutral plane, are influenced by the available soil-column interface side friction, spacing of the columns, and fill height. "Installation effects of controlled modulus column ground improvement piles on surrounding soil.". [Extracted from the article]