invention to a change of guide groove fig8 shows a scheme of an embodiment preferred of the means associated to the vehicle it is possible to observe that the principle of change of guide is the drive of an electromagnet 38 arranged to move a retractable element associated to the guide set as movable fin 41 forced by the spring 40 by means of which a change of guide is made in a section of track adequately designed for it so as it is indicated schematically in fig9 the key is that said fin 41 can sink to make contact with a deeper zone 43 to prevent that it exists problems in the contacting point between the two guide grooves 42 to force to the vehicle to follow the alternative guide it is possible to emphasize that the fact to share the same tracks of feeding by different vehicles implies the necessity to cause that the feeding means are scalables according to the final number of vehicles that circulate for this purpose it has been foreseen the use a new module of feeding like the one shown in the fig1 this is based on a base 48 u201c pack of.