Longitudinal cracks are parallel to the pavement’s centerline or laydown direction. They may be caused by:
A poorly constructed paving lane joint.
Shrinkage of the AC surface due to low temperatures or hardening of the asphalt, or daily temperature cycling, or both.
A reflective crack caused by cracking beneath the surface course, including cracks in PCC slabs, but not PCC joints.
Transverse cracks extend across the pavement at approximately right angles to the pavement centerline or direction of laydown. These types of cracks are not usually load-associated.