TM 5-826-6/AFR 93-5
Figure A-14. High severity block cracking case 2.
(3) Measuring procedure. Block cracking is measured in square feet of surface area and usually occurs at one
severity level in a given pavement section. However, any areas of the pavement section having distinctly different levels of
severity should be measured and recorded separtely.
d. Corrugation, distress 44.
(1) Description. Corrugation is a series of closely spaced ridges and valleys (ripples) occurring at fairly regular
intervals (usually less than 5 feet) along the pavement. The ridges are perpendicular to the traffic direction. Traffic actio n
combined with an unstable pavement surface or base usually causes this type of distress.
(2) Severity levels.
(a) Low severity level (L). Corrugations are minor and do not significantly affect ride quality (see
measurement criteria below and illustration in fig. A-15).
Figure A-15. Illustration of corrugation.