Abstract: A railroad track tamper control system of the type wherein the grade rail is jacked relative to a reference line, the level rail is cross leveled to the grade rail before tamping, and the tamper frame is relatively independent of the jacking; in which a cross level sensor is mounted on the main tamper frame to free it from jacking vibrations and vertical position sensors measure the jacked elevations of both the grade and level rails relative to the tamper frame. The system cross levels the level rail by comparing the elevation of the grade and level rails relative to the tamper frame and adjusting that comparison by any out-of-cross level of the frame sensed by the cross level sensor.