Work out train braking distance instantly with clear inputs, formula shown and shareable results.
Braking distance is v squared divided by twice the deceleration, plus the distance covered during brake build-up. A falling gradient subtracts g times the gradient from the available deceleration, which is why descending grades lengthen stopping distance sharply and drive signal spacing on mountain lines.
Braking distance
d = v x t_buildup + v^2 / (2 x (a - g x gradient))
Rail results are planning estimates only. Verify against the infrastructure manager's rule book, approved braking curves and applicable railway safety regulations.
Air brakes propagate along the train, so a long freight train can take 10-20 seconds to reach full braking, covering hundreds of metres at line speed.
Roughly 0.4-0.6 m/s2 for loaded freight, 0.8-1.2 m/s2 for passenger stock in service braking and up to 1.5 m/s2 in emergency.