The height of the high-speed section of the sorting slide. Design of high-speed section of the marshalling hump. To prove mathematically the absence of theoretical basis of the formula by which the height of the first profile section of the marshalling hump is calculated in current method of calculation of marshalling humps. The paper uses the theorem on the change of kinetic energy for a non-free material point in the final form, known from theoretical mechanics. The results of the research revealed that the formulas by which the height of the first profile section of the marshalling hump is calculated contradict the theorem on the change of kinetic energy for a non-free material point in the final form. The results of the research can be used in the processing of the normative-technical document on the design of hump devices on railways and making adjustments to the dynamics of rolling the car in textbooks for universities of railway transport. The results of the calculations proved the incorrectness of the derivation of the formula for calculating the height of the first profile section of the marshalling hump in the normative-technical document “Rules and standards for the design of sorting devices on the railways with gauge 1 520 mm”.