Work out rail gradient resistance instantly with clear inputs, formula shown and shareable results.
Train resistance is the sum of gradient resistance (mass times g times gradient), rolling resistance (a few newtons per tonne) and aerodynamic resistance growing with the square of speed. On any gradient above about 0.5% the gradient term dominates, which is why railway alignments are kept so flat.
Train resistance
R = m x g x grade + m x rolling coefficient + air term; power = R x v
Rail results are planning estimates only. Verify against the infrastructure manager's rule book, approved braking curves and applicable railway safety regulations.
Steel wheel on steel rail gives a rolling coefficient of roughly 0.002, around a tenth that of a truck tyre on asphalt, which is the fundamental efficiency advantage of rail.
About 98 N per tonne, roughly forty times the rolling resistance, so a 1,200 t train needs an extra 118 kN of tractive effort.