Determination of Equivalent Single Axle Load (ESAL) Factor for Georgia Pavement Design

US Transportation Collection2021PDFTech ReportKim, S. SonnyYang, Jidong JDurham, Stephan A.Kim, In KeeYaghoubi, Narges TahaeiUniversity of Georgia. College of EngineeringGeorgia. Department of Transportation. Office of Performance-Based Management & ResearchUnited States. Department of Transportation. Federal Highway AdministrationGeorgia. Dept. of Transporation. Office of Performance-Based Management and ResearchGeorgiaUnited StatesEquivalent single axle loadsPavement designTrucksWeigh in motionSensorsPavement ME SoftwareTraffic InputsFHWA-GA-21-1804PI# 0016338Final Report (October 2018\u2013July 2021)The Georgia Department of Transportation (GDOT) is currently using the 1972 AASHTO Pavement Design Guide in which the damage caused by traveling vehicles in the pavement\u2019s design life is defined in terms of equivalent single axle load (ESAL). The last updates of truck ESAL factors in Georgia were made in 1984. Thus, there is a need to update ESAL factors due to the changes in traffic patterns over time, especially during recent years. In this study, truck ESAL factors were updated using actual traffic loadings from weigh-in-motion (WIM) sensors installed throughout Georgia. As GDOT is adopting the pavement mechanistic\u2013 empirical (ME) design, customized truck traffic classification (TTC) groups were developed as well to simplify the pavement ME design process, which requires high-dimensional traffic feature inputs by categories, including vehicle class distributions (VCDs), monthly distribution factors (MDFs), hourly distribution factors (HDFs), and normalized axle load spectra (NALS). Specifically, an effective data analytics procedure was developed to reduce the high-dimensional traffic features by stratified principal component analysis (PCA), followed by K-means clustering to establish the appropriate TTC groups. For a case study, the performance of two typical pavement designs was evaluated using the AASHTOWare\uae Pavement ME Design software with respect to two scenarios of traffic inputs: (1) the derived cluster-based groups, and (2) the national default TTC groups. The results indicated that direct application of the national default TTC groups resulted in over-design of pavement structure, especially the jointed plain concrete pavement (JPCP), in Georgia. Therefore, it is recommended that customized TTC groups derived from state-specific WIM data should be used.120