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10 Table 3. Distribution of LTPP test sections by states. Climate No. of Climate No. of Climate No. of State State State Zone Sections Zone Sections Zone Sections Alabama WNF 14 Massachusetts WF - South Dakota WF 3 Alaska WF 4 Michigan WF 12 Tennessee WF/WNF 4/1 Arizona DNF 11 Minnesota WF 21 Texas DF/ WNF 2/28 Arkansas WNF 2 Mississippi WNF 13 Utah DF - California DNF/WNF 5/3 Missouri WF 23 Vermont WF 4 Colorado DF 9 Montana DF - Virginia WF/WNF 1/3 Connecticut WF 6 Nebraska DF/ WF - Washington DF 1 Delaware WF 1 Nevada DF/DNF - West Virginia WF - D.C. WF 1 New Hampshire WF 1 Wisconsin WF 20 Florida WNF 2 New Jersey WF 21 Wyoming DF - Georgia WNF 2 New Mexico DF/DNF - Alberta WF 4 Idaho DF/WF - New York WF 4 British Columbia DF - Illinois WF 13 North Carolina WF/WNF 2/11 Manitoba WF 9 Indiana WF 14 Ohio WF 3 New Brunswick WF 1 Iowa WF 10 Oklahoma WF/WNF 1/11 Nova Scotia WF - Kansas WF 13 Oregon WNF 1 Ontario WF 3 Kentucky WF 2 Pennsylvania WF 7 Quebec WF 9 Maine WF 6 Rhode Island WF - Saskatchewan DF 4 Maryland WF 14 South Carolina WNF 1 - - - shift coefficients, C1 and C2). The method of making this con- order to have reliable and values for the S-shaped curves version is explained in Appendix G. These six properties of the that were fitted to the distress data, at least three separate and master curve of extracted binders were measured and reported sequential observations of distress were required. In some in SHRP studies (4) and tabulated in Appendix G. This infor- cases, no distress data were recorded on the old pavement mation was used together with the calculated temperature to surface prior to overlay and a mathematical method had to be determine the input to the ANN models of Witczak's 1999 (2) devised to estimate the original amount of cracking which and 2006 (3) models of the complex modulus. was subject to reflection. The mathematical method used was The overlay test sections in Texas and New York City con- the Systems Identification method which is described in tributed high quality data and the unique feature of having detail subsequently in this chapter and also in Appendix L. the overlays reinforced by geosynthetic interlayers. Traffic Data Collection Pavement Distress Data Collection Traffic data is a key element for the design and analysis of The pavement distress data included the total length and a HMA overlay structure or a new pavement structure. For severity of the cracks in the old pavement surface prior to the compatibility with the MEPDG, traffic was described by the placement of the overlay and the length and severity of the actual load distribution (spectrum) for each axle type (single, cracks reflected through the overlay. Only transverse cracks tandem, tridem, or quadrem axle) for each vehicle (truck) were considered as reflection cracks in each test section. In class or number of tires (single or dual).