Buried structures under airport runways and taxiways must be able to support the large aircraft live loads as well as the dead load from the soil and runway pavement. Additional wheels on the landing gear will spread the aircraft weight over proportionally more area to limit stress in the pavement, but the load on buried structures may increase because of the overlap of individual wheels or groups of wheel loads. The design of buried structures is dependent on the pavement material and thickness, distributed live load magnitude, shape and size of the structure and depth of fill over the top of the structures.