shown in Table 3.29, the discount rate was unrealistically assumed as zero. Figure 3.59 shows the effect of discount rates from 0 to 6 percent. As is typically the case, the analysis is very sensitive to the discount rate. In this example, the rigid pavement pro- vides the lower life cycle cost when the discount rate is less than about 1.7 percent, and the flexible pavement when the rate is higher. It is apparent that the discount rate must be selected with great care.