@article{sayyady_stone_list_jadoun_kim_sajjadi_2011, title={Axle load distribution for mechanistic-empirical pavement design in North Carolina multidimensional clustering approach and decision tree development}, number={2256}, journal={Transportation Research Record}, author={Sayyady, F. and Stone, J. R. and List, G. F. and Jadoun, F. M. and Kim, Y. R. and Sajjadi, S.}, year={2011}, pages={159–168} }
 @article{sayyady_stone_taylor_jadoun_kim_2010, title={Clustering Analysis to Characterize Mechanistic-Empirical Pavement Design Guide Traffic Data in North Carolina}, ISSN={["2169-4052"]}, DOI={10.3141/2160-13}, abstractNote={ This paper presents attempts to generate regional average truck axle load distribution factors (ALFs), monthly adjustment factors (MAFs), hourly distribution factors (HDFs), and vehicle class distributions (VCDs) for North Carolina. The results support Mechanistic–Empirical Pavement Design Guide (MEPDG) procedures. Weigh-in-motion data support the analysis and generate seasonal factors. MEPDG damage-based sensitivity analysis shows that pavement performance is sensitive to North Carolina site-specific ALFs, MAFs, and VCDs. Similar results occur for national default values of ALF, MAF, and VCD. Hierarchical clustering analysis based on North Carolina ALFs and MAFs develops representative seasonal traffic patterns for different regions of the state. Findings show that seasonal truck traffic has distinct characteristics for the eastern coastal plain, the central Piedmont, and the western mountains. A simplified decision tree and a related table help the pavement designer select the proper representative patterns of ALF and MAF. To develop VCD factors, the approach uses 48–h classification counts and a seasonal factoring procedure to account for day-of-week and seasonal variations. The approach incorporates site-specific truck traffic to improve the accuracy of pavement design. On the basis of sensitivity analysis results, pavement performance is found to be insensitive to North Carolina site-specific and national default values of HDF; thus, the average statewide HDF values may be used as input to MEPDG. Specific contributions of this research are the relative insensitivity of pavement performance to HDF, the use of 48-h classification counts to estimate VCD inputs, and a decision tree and table to help pavement designers select the proper ALF and MAF inputs. }, number={2160}, journal={TRANSPORTATION RESEARCH RECORD}, author={Sayyady, Fatemeh and Stone, John R. and Taylor, Kent L. and Jadoun, Fadi M. and Kim, Y. Richard}, year={2010}, pages={118–127} }
 @article{corley-lay_jadoun_mastin_kim_2010, title={Comparison of Flexible Pavement Distresses Monitored by North Carolina Department of Transportation and Long-Term Pavement Performance Program}, ISSN={["2169-4052"]}, DOI={10.3141/2153-10}, abstractNote={ The Long-Term Pavement Performance (LTPP) program has collected pavement distresses for general pavement study (GPS) sites throughout the country. These sites were used in the initial calibration of the Mechanistic–Empirical Pavement Design Guide, so it is important for states to compare their distress identification procedures and results with the LTPP distresses as part of the local calibration process. North Carolina has 24 GPS sites, of which four are concrete, one went out of service very early, and the remainder are flexible pavements. This paper focuses on the flexible pavement distresses. The GPS sites are 500-ft sections of much longer roadways. The LTPP distress data were extracted for the North Carolina Department of Transportation (NCDOT) GPS sites. Corresponding locations and their distress histories were pulled from the NCDOT pavement management system. In addition, rut depth measurements taken by high-speed profilometer were obtained for many of the sections for comparison with LTPP rut depth measurements. As might be expected, the LTPP walking survey revealed higher amounts of distress than the NCDOT windshield survey. Alligator cracking is the major distress for NCDOT pavements, and a roughly two-to-one relationship was found between alligator cracking by LTPP compared to NCDOT. Rut depths measured by LTPP were also found to be larger than those measured by high-speed profilometer, but in either measure, rut depths measured for NCDOT sections were low (less than 10 mm for all sites). }, number={2153}, journal={TRANSPORTATION RESEARCH RECORD}, author={Corley-Lay, Judith and Jadoun, Fadi M. and Mastin, Jeffery Neil and Kim, Y. Richard}, year={2010}, pages={91–96} }