Traction and braking control system for a railway train set comprising a leading master locomotive, at least one trailing or intermediate slave locomotive and a plurality of carriages or cars, and provided with a pneumatic braking system and in which each of said locomotives (ML, SL) comprises traction apparatus and braking apparatus associated with respective manual control devices (3; 4) and a respective electronic control unit (ECUM; ECUS) and related signal transceiver means (5, 6) through which the electronic control unit (ECUM) of the master locomotive is able to communicate with the control unit (ECUS) of said at least one slave locomotive; the arrangement being such that the traction apparatus and the braking apparatus of the slave locomotive can be controlled by the master locomotive; the control unit (ECUM) in the master locomotive being associated with: - sensor means designed to provide said control unit with signals indicating the speed and/or the acceleration of the master locomotive and the commands given by the driver to the traction control devices and the braking control devices; - memory means storing data indicating the composition of the train set, data defining a mathematical model of the longitudinal dynamics of the train set, data defining a profile of the section on which the train set is travelling; - positioning means for providing signals indicating the instantaneous position of the train set along said section; and - a human-machine interface for providing information to the driver; - generate in a predetermined manner and as a function of the data stored in said memory means and the information provided by said sensor means and the positioning means, signals for controlling traction and/or braking, and to transmit said control signals to the control unit (ECUS) of said at least one slave locomotive through said transceiver means (5, 6); the system being characterized in that: the memory means store data defining at least one predetermined operational objective; the control unit (ECUM) of the master locomotive is designed to - check whether the commands given by the driver using the traction control devices and the braking control devices are consistent with said at least one predetermined operational objective, and to use the human-machine interface to provide the driver with instructions on how to operate said control devices (3, 4) to achieve said predetermined operational objective; and the control unit (ECUS) in each slave locomotive is associated with the same means and devices that are associated with the control unit (ECUM) of the master locomotive; the control units (ECUM, ECUS) of the master locomotive and of the slave locomotive or locomotives being designed to operate selectively as a master control unit or as a slave control unit. - sensor means designed to provide said control unit with signals indicating the speed and/or the acceleration of the master locomotive and the commands given by the driver to the traction control devices and the braking control devices; - memory means storing data indicating the composition of the train set, data defining a mathematical model of the longitudinal dynamics of the train set, data defining a profile of the section on which the train set is travelling; - positioning means for providing signals indicating the instantaneous position of the train set along said section; and - a human-machine interface for providing information to the driver; - generate in a predetermined manner and as a function of the data stored in said memory means and the information provided by said sensor means and the positioning means, signals for controlling traction and/or braking, and to transmit said control signals to the control unit (ECUS) of said at least one slave locomotive through said transceiver means (5, 6); the system being characterized in that: the memory means store data defining at least one predetermined operational objective; the control unit (ECUM) of the master locomotive is designed to the memory means store data defining at least one predetermined operational objective; the control unit (ECUM) of the master locomotive is designed to - check whether the commands given by the driver using the traction control devices and the braking control devices are consistent with said at least one predetermined operational objective, and to use the human-machine interface to provide the driver with instructions on how to operate said control devices (3, 4) to achieve said predetermined operational objective; and