A flexible pavement has a $4-$inch hot$-$mix asphalt $($HMA$)$ wearing surface, an $8-$inch densegraded crushed stone base, and an $8-$inch crushed stone subbase. The pavement is on a soil with a CBR of $4.$ The pavement was designed with $93\%$ reliability, an overall standard deviation of $0\mathrm{.}3,$ and a $\frac{?}{{?}_{\frac{?}{?}}}$ PSI of $2\mathrm{.}2($and TSI of $2\mathrm{.}5).$ The drainage coefficients are $1.$ How many $42-$kip single$-$axle loads can be carried before the pavement reaches its TSI $($with the given reliability$)?$

A flexible pavement has a structural number of $3\mathrm{.}8,$ the initial PSI is $4\mathrm{.}7$ and the terminal serviceability is $2\mathrm{.}5.$ The soil has a resilient modulus of $13,000.$ The overall standard deviation is $0\mathrm{.}4$ and the design reliability is $95\%.$ The pavement is currently designed for $1800$ equivalent $18-$kip single$-$axle loads per day. What is the pavement's design life in years? If the number of $18-$kip single$-$axle loads were to increase by $50\%,$ by how many years would the pavement's design life be reduced?