Edge Cracking is primarily caused by what condition?

• A. Thermal expansion of asphalt
• B. Settlement of underlying material aggravated by heavy traffic or vegetation
• C. Vehicle impact
• D. Pothole formation

Answer: (B)

Edge cracking occurs when the edge of the pavement loses support from the layers beneath, causing differential settlement or shifting at the edge under traffic. When the subgrade or subbase settles or is undermined, the edge becomes lower than the rest of the pavement, and the stresses from load transfer and traffic cause a crack to form along the edge. Heavy traffic increases those stresses, and vegetation can worsen the problem by changing moisture conditions or root intrusion that undermines the edge support. The other factors aren’t the primary cause: thermal expansion mainly affects surface curling or transverse cracks, vehicle impact tends to create localized damage or potholes, and pothole formation is a different distress mode.