Severity levels How to Measure Possible causes

28 Bumps are small, localized, upward displacements of the pavement surface. They are different from shoves in that shoves are caused by unstable pavement. Sags are small, abrupt, downward displacements of the pavement surface. If bumps appear in a pattern perpendicular to traffic flow and are spaced at less than 3 m 10 ft, the distress is called corrugation. Distortion and displacement that occur over large areas of the pavement surface, causing large or long dips Figure 2.11 show Bumps and Sags ASTM D6433. Figure 2.11 Convexities and Concavities GTC, 1998

b. Severity levels

- Low level of intensity L: a level which affects the quality of a simple command Riding quality. - Medium level of intensity M: a level which affects the average quality of leadership. - Higher level of intensity H: a level which severely affects the quality of leadership.

c. How to Measure

The measured concavities and Convexities Surface longitudinal, and if met this defect with cracks they record as well. Measured by the area affected by the defect length of the affected area multiplied by one meter, and the defect density is 29 calculated by dividing the area affected by the total area of the section scanned multiplied by one hundred.

d. Possible causes

These reasons include the following: i. Bulge or curvature of the concrete slabs of concrete under the asphalt surface. ii. Leakage and higher materials in the cracks due to traffic loads.

2.3.2.4 Corrugation

a. Description

Corrugation is a series of closely spaced ridges and valleys ripples occurring at fairly regular intervals 1.5 meters along the pavement see Figure 2.12. The ridges are perpendicular to the traffic direction. Traffic action combined with an unstable pavement surface or base usually causes this type of distress. Figure 2.12 Corrugations GTC, 1998

b. Severity levels