A rigid pavement on a new interstate with 3 lanes in each direction has been conservatively designed with a 12-inch slab, an Ec of 5.5 million psi, a concrete modulus of rupture of 700 psi, a load transfer coefficient of 3.0, an initial PSI of 4.5, and a TSI of 2.5. The overall standard deviation is 0.35, the modulus of subgrade reaction is 290 lb/in3, and the drainage coefficient is 0.9. The pavement was designed for 600 30-kip tandem axles per day and 1400 20-kip single axle loads per day total for all 3 lanes. If the desired reliability is 90%, how long will the pavement last in years