Prediction of fatigue cracking in asphaltic pavement under local traffic conditions: Application to Semel-Patel highway-Duhok

Fatigue cracking was among the most prevalent types of distress affecting asphalt concrete pavements in Iraq, which had been exacerbated by base destabilisation and inadequate subgrade drainage and resulted from recurrent traffic loads that exceeded design specifications. The study focused on a 15-kilometer section of the Semel-Patel Highway near Duhok, where this type of cracking had significantly increased maintenance costs, however addressing it could help reducing expenditures on long term. The NCHRP mechanistic-empirical fatigue life prediction model (NCHRP 9–44A/PMED) was used to forecast the number of load repetitions that are possible until cracking occurred. Layer stiffness, traffic spectra, climate, and drainage condition were among the field condition inputs that had been adjusted by laboratory testing and field observations. Notable results revealed: the subgrade moisture and binders had a significant impact on the expected fatigue life, underscoring the significance of appropriate drainage enhancements and binder selection to prolong pavement life. This model proposed as a decision-support tool for pavement design optimization and maintenance management.