Problem $1$A new flexible pavement is to be built on a major $2-$lane expressway extension from Hatch to Deming. Traffic forecasting analysis has yield an estimate demand of $20$ million ESALs over the $20-$year performance period $($wt$18=20\backslash$times $106).$ Local conditions:Average resilient modulus of the subgrade $($Mr$)$: $5,000$ psiResilient modulus of the base course material $($E$2)$: $30,000$ psiResilient modulus of the subbase course material $($E$3)$: $15,000$ psiResilient modulus of the asphalt concrete layer $($E$1)$: $450,000$ psiBoth the base and subbase material exhibit excellent drainage. Four bids have been submitted to your office for review: Bid $1$: $$1,132,000\mathrm{.}00$ per mileAsphalt thickness $($D$1)$: $7\mathrm{.}5$ inchesBase thickness $($D$2)$: $8$ inchesSubbase thickness $($D$3)$: $8$ inches Bid $2$: $$890,000\mathrm{.}00$ per mileAsphalt thickness $($D$1)$: $3$ inchesBase thickness $($D$2)$: $10$ inchesSubbase thickness $($D$3)$: $11$ inches Bid $3$: $$970,000\mathrm{.}00$ per mileAsphalt thickness $($D$1)$: $8$ inchesBase thickness $($D$2)$: $3$ inchesSubbase thickness $($D$3)$: $4$ inches Bid $4$: $$945,000\mathrm{.}00$ per mileAsphalt thickness $($D$1)$: $6$ inchesBase thickness $($D$2)$: $5$ inchesSubbase thickness $($D$3)$: $8$ inches