# Curve Resistance - Inaccurate Formulas - Formulas Which Try To Account For Superelevation

Formulas Which Try To Account For Superelevation

Астахов proposed the use of a formula which when plotted is in substantial disagreement with the experimental results curves previously cited. His formula for curve resistance (in kgf/tonne) is the sum of two terms, the first term being a conventional k/R term with k=200 instead of 700. The second term is directly proportional to (1.5 times) the absolute value of the unbalanced acceleration in the plane of the track and perpendicular to the rail, such lateral acceleration being equal to the centrifugal acceleration (v^2 / R)cos theta, minus the gravitation component opposing this acceleration: g tan theta, where theta is the angle of the banking due to superelevation. Multiplying any of these accelerations by the appropriate mass (in kg) (of the rail car, of the mass allocated to one wheel, etc.) results in the corresponding force per Newton's 2nd law. Then multiplying by 1.5 converts it to curve resistance in units of kgf. Note that the proposed 1.5 multiplier represents both a constant of proportionality and a conversion of force from Newtons to kgf.