Automated Pavement Distress Collection Techniques (2004)

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64 Where applicable, sources are provided (in parentheses) from the references used in this synthesis report. Alligator cracking—See fatigue cracking. Crack—Fissure or discontinuity in the pavement surface not necessarily extending through the entire thickness of the pavement (63). Digital image—Image that is stored in numerical form. Digitize—Process of converting analog images to digital. Fatigue cracking—Series of small, jagged, interconnecting cracks caused by the failure of the asphalt concrete sur- face under repeated traffic loading (also called alligator cracking) (11). Fault—Difference in elevation between opposing sides of a joint or crack (11). Flexible pavement—Pavement structure that maintains inti- mate contact with and distributes loads to the subgrade and that depends on aggregate interlock, particle friction, and cohesion for stability. Global Positioning System (GPS)—Worldwide radio navi- gation system formed from a constellation of 24 satellites and their ground stations. International Roughness Index (IRI)—Pavement roughness index computed from a longitudinal profile measurement using a quarter-car simulation at a simulation speed of 50 mph (80 km/h) (63). JPEG—Joint Photographic Experts Group standard for com- pressing data. Longitudinal cracking—Cracks in the pavement predomi- nantly parallel to the direction of traffic (63). Longitudinal profile—Perpendicular deviations of the pave- ment surface from an established reference parallel to the lane direction, usually measured in the wheel tracks (63). Mile point—Location reference used in highway work, usu- ally expressed as a logged mileage along a specific route from a political boundary or roadway intersection. Mile post—Physical marker of a mile point. Network-level data—Data supporting pavement manage- ment decisions on a roadway network or system basis. Patch—Portion of pavement surface that has been replaced or additional material that has been applied to the pave- ment after original construction (63). Pavement condition—Qualitative representation of distress in pavement at a given point in time (63). Pavement distress—External indications of pavement defects or deterioration (63). Pavement performance—Ability of a pavement to fulfill its purpose over time (63). Photologging—Process of capturing roadway or pavement images by photographic methods. Present serviceability—Current condition of a pavement (traveled surface) as perceived by the traveling public (63). Profiler—Equipment used to measure the profile of the trav- eled surface. Profilometer—Equipment used to measure traveled surface roughness (63). Project-level data—Data supporting pavement management decisions on a discrete project or roadway segment basis. Rideability—Subjective judgment of the comparative dis- comfort induced by traveling over a specific section of highway pavement in a vehicle (63). Roughness—Deviation of a surface from a true planar surface with characteristic dimensions that affect vehicle dynamics and ride quality. Rutting—Longitudinal surface depressions in the wheel paths (11). Transverse cracking—Cracks in the pavement that are pre- dominantly perpendicular to the direction of traffic (63). Transverse profile—Vertical deviations of the pavement sur- face from a horizontal reference perpendicular to the lane direction (63). Wheel track—Line or path followed by the tire of a road vehicle on a traveled surface (63). GLOSSARY