C. With a 12-year design life, a flexible pavement was developed for the following daily traffic: 1300 single axles weighing 8,000 pounds each, 900 tandem axles weighing 15,000 pounds each, 20 single axles weighing 40,000 pounds each, and 200 tandem axles weighing 40,000 pounds each. 4 inches of hot-mix asphalt (HMA) wearing surface, 4 inches of hot-mix asphaltic base, and 8 inches of crushed stone subbase were used to construct the roadway. All drainage coefficients were 1.0, the total standard deviation was 0.5, the APSI was 2.0 (with a TSI of 2.5), and the reliability was 70%. What was the subgrade's soil resilient modulus when it was designed?
Extracted text: C. With a 12-year design life, a flexible pavement was developed for the following daily traffic: 1300 single axles weighing 8,000 pounds each, 900 tandem axles weighing 15,000 pounds each, 20 single axles weighing 40,000 pounds each, and 200 tandem axles weighing 40,000 pounds each. 4 inches of hot-mix asphalt (HMA) wearing surface, 4 inches of hot-mix asphaltic base, and 8 inches of crushed stone subbase were used to construct the roadway. All drainage coefficients were 1.0, the total standard deviation was 0.5, the APSI was 2.0 (with a TSI of 2.5), and the reliability was 70%. What was the subgrade's soil resilient modulus when it was designed?