This module describes the challenges faced in asphalt paving operation. How the air void in the pavement effect the durability of the pavement. What will happen if the field air voids are less than the designed air voids? What happen when the field air voids are more than the designed air voids? How the interlayer tolerances effect the performance of the bituminous layer are being described in the module. What will happen when the WMM layer is being laid with plus 10mm tolerance to the pavement performance.