What is the maximum surface variation allowed between two contacts with the surface when using a straightedge?

The maximum surface variation allowed between two contacts with the surface when using a straightedge is established to ensure quality and performance standards in asphalting work. The specific limit of 4 millimeters indicates that any deviation from a perfectly flat surface must not exceed this range in order to maintain structural integrity and proper drainage of the asphalt. Variations exceeding this threshold could lead to issues such as water pooling, reduced longevity of the surface, and increased wear and tear on vehicles and pedestrians. Adhering to this standard helps ensure a smoother and safer surface, thereby promoting a higher quality construction outcome in asphalt projects.