The implementation of the Empirical-Mechanistic Pavement Design Guide (MEPDG) method for flexible and rigid pavements requires numerous input parameters. Most of these parameters can be easily determined while some require best estimates that are usually extracted from available literature. This thesis identifies the most critical input parameters in terms of their effects on the damage of pavements and their influence on the determination of the number of corrective maintenance cycles to be performed during the design life of pavements. It was found that for flexible pavement, change in the average monthly temperature by as little as results in large differences in the number of corrective maintenance cycles. Also, consistently with simple mechanics concepts, pavements on stiffer foundations performed better under the load and hence, required fewer number of the corrective maintenance cycles than those founded on more flexible soils. Also, variations in truck weights affected the outcome in terms of the estimated number of corrective maintenance cycles for flexible pavement. Hence, better estimates of the number of corrective maintenance cycles can be obtained when the analysis was based on larger numbers of truck samples. On the contrary, no significant difference in the final estimation of the number of corrective maintenance cycles was found for rigid pavements even when the average monthly temperatures were increased or decreased by as much as . Moreover, no major difference was observed when a larger sample of trucks was used as input for the analysis. Similarly, change in ambient temperature which is directly related to the differential temperature on the top and the bottom of the slab that may lead to the curling of the slab and faulting, was found not to be critical. Similar to the results obtained for flexible pavements, rigid pavement with stiffer foundation properties performed better in terms of the number of corrective maintenance cycles as they required fewer corrective maintenance cycles.