【国外标准】 Standard Practice for Generating Pavement Surface Cracking Indices from Digital Images

5.1 The PSCI provides a measure of the cracking observed on the pavement surface. It provides a quantitative and rational basis for rating pavement surface cracking to aid in determining maintenance and repair needs and priorities. Periodic monitoring of the PSCI can be used to establish feedback on pavement performance for validation or improvement of current pavement design and maintenance procedures. The PSCI is calculated from the PSCM.5.2 The PSCM uses the openness or aperture size of the pavement surfacing caused by cracking as the objective function. This is a measure of the surface integrity due to cracking that relates to the area that could potentially admit surface water.5.3 It also relates to the loss of horizontal tensile integrity at the surface because that is proportional to the total length of cracks and to interparticle load transfer, which is related in part to crack width.5.4 It is, however, a purely physical dimensional measure and has no prior dependency on cause or type of cracking.5.5 Any evaluation of the cause of the cracking, or of its impact on pavement performance, would be made independently together with other factors relevant to the particular purpose, as elaborated later.5.6 Sealed cracks, potholes, and patching are not included in the PSCM and PSCI calculations.1.1 This practice covers the quantification of pavement surface cracking from digital 2D images or 3D data (or both) of the pavement surface.1.2 The objectives of this standard are to eliminate human subjectivity and intervention in the process of generating cracking indices, to define cracking metrics and other required parameters objectively, and to enable all users of the standard to produce the same cracking indices given the same cracking data.1.3 The cracking indices are unitless and are calculated in a straightforward manner from fundamental measurements of length, width, and area as defined in this standard.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Specific precautionary statements are given in Section 7.1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.