Rail profile indicators for wheel-rail contact geometry: Correlation with equivalent conicity

The extensive operational mileage and heavy traffic loads of railways impose stringent requirements on rail profile quality, as it directly governs wheel-rail contact geometry and vehicle hunting stability. However, existing rail evaluation indicators focus primarily on geometric deviations without establishing a clear link to contact parameters, limiting their effectiveness for dynamics-oriented maintenance. This study first proposes a set of novel rail profile indicators from two complementary perspectives of wear morphology and geometric characteristics. Based on field measurements of rail profiles from high-speed railway lines, the correlation between each indicator and wheel-rail contact parameters is then analyzed under both symmetric and asymmetric rail wear conditions, revealing the mapping relationship from geometric features to equivalent conicity. Finally, an orthogonal experimental design is employed to eliminate confounding factors such as wheel profile, gauge, and rail cant, thereby validating the robustness of the proposed indicators. Results show that the rail head indentation exhibits the strongest correlation with nominal equivalent conicity, achieving a Spearman coefficient exceeding 0.95 and an R 2 value of 0.97, followed by other geometric indicators. The proposed indicators effectively capture the spatial heterogeneity and left-right asymmetry of rail wear, and the derived regression equations provide a quantitative mapping from geometric features to contact parameters. This research bridges the gap between rail profile geometry and wheel-rail contact behavior, offering a scientific basis for condition-based rail grinding decisions and contributing to enhanced operational stability and cost-effective maintenance of high-speed railways.