Video narration
Why doesn't a wheel load punch straight down through flexible pavement into the soil, like your weight pressing on one spot of a hard floor? Standing on a mattress, your weight spreads through supporting material beyond the exact contact point. A tire starts with a small contact area at the surface. The load path widens through surface course, base, and subbase, reaching larger areas as it descends. It is three-dimensional, not a perfectly vertical cone. The load does not stay concentrated beneath the tire. Particle contact, aggregate interlock, and friction pass the force outward through the layers. Unlike a rigid slab, flexible pavement does not carry the wheel as one solid plate. Adequate thickness, strong materials, compaction, and controlled moisture limit deformation. The load is redistributed, not lost. At the subgrade, it acts over a wider area at lower stress-so it doesn't punch through the soil.