Determine the thickness of flexible pavement layer 2 given the following:
FACTS:
Total Structural Number required = 7.0
Total number of layers = 2
Layer 1 consists of asphalt concrete with a strength coefficient of 0.46
Layer 1 thickness = 6 inches
Layer 2 consists of granular base with a strength coefficient of 0.15
Answer - SN - D1a1 + D2a2
D2 = SN - D1a1 / a2 = (7.0 - 6 * 0.46) / 0.15 = 28.3"