Problem $3$:

For the same pavement as in Example $2\mathrm{.}9$ in the textbook, if the $12,000-$lb load is applied over a set of dual tires with a center$-$to$-$center spacing of $12in.(292mm)$ and a contact pressure of $80$ psi, as shown in Figure below, determine the critical tensile strain in the asphalt layer $.$