Abstract: There is shown a safety control system for a self-propelled road roller having hydrostatic transmission, which includes a prime mover, an hydraulic pump driven by the prime mover and included in a main hydraulic circuit incorporating a motor with a power-off brake device, a check valve bridge with a ventable relief valve and a main control valve, and means for selecting automatically the speed and a predetermined operating speed, the speed selecting means comprise a secondary hydraulic circuit including means operatively connectible with the prime mover speed control means and controllable by the ventable relief valve in accordance with the operation of the main control valve.