Rail Profile Matching Assessment and Selection for Sharp Radius Curves in Urban Metro: A Case Study

Abstract Urban rail transit systems contain numerous sharp radius curves where rail fatigue defect occurs frequently. In severe cases, this leads to extensive rail scaling, rail surface fatigue cracks, and intensified wheel-rail vibration and noise. Appropriate rail profiles can effectively optimise wheel-rail contact status and mitigate the deterioration development of wear and wheel/rail fatigue defect. Addressing this issue, this paper combines field testing evaluation and simulation analysis methods to establish a metro vehicle-track coupled dynamics model validated by measured data. Three profile schemes and three simulation scenarios were considered to comprehensively study and analyze the matching performance between sharp radius curve rail profiles and actual wheel profiles from perspectives of wheel-rail contact stress distribution, fatigue and wear indices, and vehicle dynamic performance. Results indicate that the 60N profile consistently exhibits optimal stress control effectiveness under all operating conditions. Compared to the traditional 60 profile condition, normal and tangential contact stress are reduced by up to 64% and 61%, respectively. Relative to the measured profile condition, stress reductions of up to 64% and 45% are achieved at the gauge corner. The 60N profile demonstrates the lowest fatigue index compared to the 60 profile and measured profile, while maintaining stable wear characteristics and improving vehicle lateral stability with reduced bogie acceleration peaks. Based on comprehensive analysis, the 60N profile is recommended as the optimal solution for both original rail profile selection and grinding target profile.