Abstract: A control algorithm developed for the master, intermediate, and group retarders of a classification yard enables control of the speed of car cuts in the switching area to achieve predetermined constant running times between the hump and the entrance into the assigned bowl track. Said another way, the retarders are controlled to maintain the same time spacing between cut centers, while moving through the switching area, as established by the humping rate. This reduces the number of misroutes due to catch-up with a preceding cut yet allows a constant humping speed. Various cut parameters, cut speeds, and curve and tangent track rolling resistances of each cut are measured and used as needed in determining the required exit for the cuts from the retarders. A different control algorithm for the tangent point regarders, one located in each bowl track, controls the speed of cuts assigned to that storage track, in accord with entry speed, cut parameters, track conditions, etc.