Problem:

Using the AASHTO design procedure design a new flexible pavement for a major interstate highway using the

following conditions:

Pavement location: Urban

Pavement functional classification: Interstate

Number of lanes: $3$ lanes in each direction

Annual growth rate: Assume $2\%$

Design period: $30$ years

Construction Materials: Surface course: HMA mix with a nominal maximum aggregate size of

$\frac{1}{2}$ inch, with $E=500,000$ psi

Binder course: Dense graded HMA mix with a nominal maximum

aggregate size of $1$ inch. Use $E=500,000$ psi

Base course: Crushed aggregate with $M_R=28,000$

Subbase course: Not used

Subgrade: $M_R=15,000$ in the dry months of May through October

$M_R=12,500$ in the wet months of November through April

Reliability: $R=90\%$

Overall standard deviation $(S_{\text{@}})$:$0\mathrm{.}45($typical for flexible pavements$)$

Traffic count: Single unit trucks $($assume $0\mathrm{.}40$ ESALs per truck$)=\frac{1872}{?}$ day

Double unit trucks $($assume $1\mathrm{.}00$ ESALs per truck$)=\frac{1762}{?}$ day

Truck trains $-$ trucks with more than $2$ units $($assume $1\mathrm{.}75$ ESALs per

truck$)=\frac{247}{?}$ day

Drainage condition: Time to drain is $1$ week, the pavement is expected to be saturated about

$15\%$ of the time