The paper aims to determine the permissible wheel load, wheel radius, and speed on a railroad considering fatigue shear stress in the rail head. In the literature, there are permissible wheel load and wheel radius formulae which consider shear fatigue limit as permissible shear stress; and hence do not offer acceptable wheel load, radius and speed. The deficiency lies in the permissible shear fatigue stress value. The permissible shear fatigue stress is suggested to be 24.4% of the tensile strength of rail steel with an assumed reliability of 99%. Addressing the deficiency, formulae are suggested for permissible wheel load, wheel radius and speed under three approaches. The formulae are generalised too considering the coefficient of friction at the wheel tread/rail interface. The permissible speed is suggested to be the minimum of two speeds based on the permissible shear fatigue stress at the wheel tread/rail interface and bending fatigue stress at the rail foot. A bending fatigue stress corresponding to a reliability of 95% is suggested for heavy haul because it makes a close balance between the two aforementioned speeds.

本文旨在通过考虑轨头中的疲劳剪切应力来确定铁路上允许的车轮载荷，车轮半径和速度。在文献中，存在允许的车轮载荷和车轮半径公式，这些公式将剪切疲劳极限视为允许的剪切应力。因此无法提供可接受的车轮负载，半径和速度。不足之处在于允许的剪切疲劳应力值。建议的允许剪切疲劳应力为钢轨抗拉强度的24.4％，假设可靠性为99％。针对这种不足，提出了三种方法下允许的车轮载荷，车轮半径和速度的公式。公式也考虑了车轮胎面/轨道界面处的摩擦系数进行了概括。根据车轮胎面/铁路交界处的容许剪切疲劳应力和铁路脚处的弯曲疲劳应力，建议允许速度为两个速度中的最小值。对于重载，建议使用对应于95％可靠性的弯曲疲劳应力，因为它在上述两个速度之间保持了紧密的平衡。