In road building one may observe that before the final layer of the pavement is placed heavy equipment, such as a road roller, is being used to further densify the soil, see Figure 12.13. This makes good sense, taking into account the influence of a pre-loading on the stiffness of a soil, as shown in Figure 12.8. Due to the passage of the heavy roller the soil will deform, and some additional soil may be needed to raise the top surface to the desired level. The result will be that when the road is completed the surface deformations will remain small. The initial cost is larger, but maintenance costs will be smaller. It may be noted that the stresses near the soil surface can be further increased by constructing picks on the surface of the roller, as shown in the figure.
