Figure B-18. Medium-severity bumps and sags.
H-Bump or sag cause high-severity ride quality (fig B-19).
How to Measure:
Bumps or sags are measured in linear feet. If bumps appear in a pattern perpendicular to
traffic flow and are spaced at less than 10 feet, the distress is called corrugation. If
the bump occurs in combination with a crack, the crack is also recorded.
Name of Distress:
Corrugation (also known as washboarding) is a series of closely spaced ridges and
valleys (ripples) occurring at fairly regular intervals-usually less than 10 feet along the
pavement. The ridges are perpendicular to the traffic direction. This type of distress
is usually caused by traffic action combined with an unstable pavement surface or
base. If bumps occur in a series of less than 10 feet, due to any cause, the distress
is considered corrugation.
L-Corrugation produces low-severity ride quality (fig B-20).
Figure B-19. High-severity bumps and sags.
Figure B-20. Low-severity corrugation.
M-Corrugation produces medium-severity ride quality (figs B-21 and B-22).