Pavement Inspection

Swelling

A swell is characterized by an upward bulge in the pavement's surface. A swell may occur sharply over a small area, or as a longer gradual wave. Either type of swell can be accompanied by surface cracking. A swell is usually caused by frost action in the subgrade or by swelling soil, but a small swell can also occur on the surface of an asphalt overlay (over PCC) as a result of a blowup in the PCC slab.

Severity Distress Example Description
Low Close-up photo of a transverse joint with a slight but visible swell in the pavement surface at the joint. A ruler has been placed across the joint in the longitudinal direction to show that there is an upward bulge in the pavement at the joint. Swell is barely visible and has a minor effect on the pavement's ride quality. Low-severity swells may not always be discernible, but their existence can be confirmed by driving a vehicle over the section. An upward acceleration will occur if the swell is present.
Medium Overview photo showing a noticeable upward bulge in the pavement surface. Swell can be observed without difficulty, and has a significant effect on the pavement's ride quality.
High Close-up photo showing an upward bulge in the pavement surface near the pavement's edge. The upward bulge is very noticeable due to a crack in the pavement surface at the apex of the bulge. Swell can be readily observed and severely affects the pavement's ride quality.