The engineering challenges it posed resulted in that stretch costing ten times as much to build as the to its south had. It was necessary to move of earth and replant 196 trees and 456 shrubs from the right-of-way to the edges. They were joined by 450 more shrubs on the slope above the road, primarily rhododendron and mountain laurel. Roosevelt, still taking an interest in the parkway, forced changes in the stonework of the Peekskill Hollow Road overpass to be more consistent with local architectural traditions. The bridge also had to be re-engineered due to the swampy ground.