The Project developed consist about an improvement of the automatic train protection (ATP) currently working in the line 4 of Metro de Barcelona. This optimization will be obtained through the implementation of the ATO (Automatic Train Operation) system, which increases the efficiency of the braking curve when the train has to change of track circuit, avoiding acceleration jumps or brakes. In the case of the driver, manual conduction, he cannot regulate correctly the changes of velocity when is going to pass from a track circuit to another one with different velocity codes. In addition, it can obtain an increasing commercial velocity, a better traffic regulation of the trains and more stability of the interval between trains in the Line 4 from FMB (Ferrocarril Metropolità de Barcelona).