The maximum commercially viable (due to weight restriction) grade for freight railroads is 2.2% ... A 2.2% grade seems insignificant to the average person, bu

The maximum commercially viable (due to weight restriction) grade for freight railroads is 2.2% ... A 2.2% grade seems insignificant to the average person, but to a freight train it is no laughing matter. Here's a serious derailment that happened in California: https://en.wikipedia.org/wiki/San_Bernardino_train_disaster#Train_derailment https://en.wikipedia.org/wiki/San_Bernardino_train_disaster#... At that grade it's not sufficient to use brakes in the individual rail cars, it's also necessary to use dynamic braking by turning electric traction motors into generators, then dissipating energy in giant resistive grids.