Problem $4.$ Design a flexible pavement $($i$.$e$.,$ provide the needed thicknesses for the subbase, base, and

surface course$)$ that will satisfy the following criteria: the pavement is designed to carry an ESAL of $2\mathrm{.}1{10}^6,$

that water drains from the pavement within $1$ day, that the pavement structure is saturated with moisture

$5\%$ of the time, that the resilient moduli of the asphalt concrete, base course, subbase, and subgrade material

are $300,000$;$21,000$;$11,000$; and $8,000,$ respectively; the initial and final serviceability indices

are $4$ and $2\mathrm{.}5$ ; the overall standard deviation is $0\mathrm{.}45$ ; and the desired reliability level is $95\%.$