Public transport system comprising: - at least one electric public transport vehicle equipped with: - a body in conductive material, - several wheels supported by a roadway, each wheel being formed by a tyre and a rim, so that the electric vehicle is considered as being electrically insulated from the road surface on which it travels, - several recharging stations placed one after the other along a public transport line, each station comprising: - at least first and second collector shoes (126,128)in order to supply electrical energy to electric vehicle when the electric vehicle travels along said first and second collector shoes (126,128), - a power supply for the first and second collector shoes (126,128)with first and second potentials, said system being characterized by comprising: a bipolar rail fixed onto the roof of the vehicle in parallel to the direction of travel of said vehicle, said bipolar rail comprising a first and second electrical conductor (110,112) each having two ends between which they extend in parallel to the direction of travel, said first and second conductors being electrically insulated from each other by means of an insulator capable of bearing a potential difference of at least 100 volts DC or AC between said two conductors, wherein the bipolar rail comprises a third electrical conductor electrically insulated from the first and second electrical conductors, electrically connected to the body of the electric vehicle, said conductor having two ends between which it extends in parallel to the direction of movement of the electric vehicle wherein the first and second collector shoes (126,128) of each station has first and second potentials different from the earth potentials and a third collector shoe which is earthed, said third collector shoe being suitable to rub against the third electrical conductor when the vehicle travels along the first and second collector shoes in order to connect the electric vehicle to earth potential at the same time as the first and second collector shoes rub against the first and second electrical conductors of said bipolar rail, and wherein each station comprises a leakage current sensor suitable to detect the existence of a leakage current between the first or the second collector shoe and the ground if the amperage of the leakage current surpasses a pre-set limit. - at least one electric public transport vehicle equipped with: - a body in conductive material, - several wheels supported by a roadway, each wheel being formed by a tyre and a rim, so that the electric vehicle is considered as being electrically insulated from the road surface on which it travels, - several recharging stations placed one after the other along a public transport line, each station comprising: - at least first and second collector shoes (126,128)in order to supply electrical energy to electric vehicle when the electric vehicle travels along said first and second collector shoes (126,128), - a power supply for the first and second collector shoes (126,128)with first and second potentials, - a body in conductive material, - several wheels supported by a roadway, each wheel being formed by a tyre and a rim, so that the electric vehicle is considered as being electrically insulated from the road surface on which it travels, - several recharging stations placed one after the other along a public transport line, each station comprising: - at least first and second collector shoes (126,128)in order to supply electrical energy to electric vehicle when the electric vehicle travels along said first and second collector shoes (126,128), - a power supply for the first and second collector shoes (126,128)with first and second potentials, - at least first and second collector shoes (126,128)in order to supply electrical energy to electric vehicle when the electric vehicle travels along said first and second collector shoes (126,128), - a power supply for the first and second collector shoes (126,128)with first and second potentials, a bipolar rail fixed onto the roof of the vehicle in parallel to the direction of travel of said vehicle, said bipolar rail comprising a first and second electrical conductor (110,112) each having two ends between which they extend in parallel to the direction of travel, said first and second conductors being electrically insulated from each other by means of an insulator capable of bearing a potential difference of at least 100 volts DC or AC between said two conductors, wherein the bipolar rail comprises a third electrical conductor electrically insulated from the first and second electrical conductors, electrically connected to the body of the electric vehicle, said conductor having two ends between which it extends in parallel to the direction of movement of the electric vehicle wherein the first and second collector shoes (126,128) of each station has first and second potentials different from the earth potentials and a third collector shoe which is earthed, said third collector shoe being suitable to rub against the third electrical conductor when the vehicle travels along the first and second collector shoes in order to connect the electric vehicle to earth potential at the same time as the first and second collector shoes rub against the first and second electrical conductors of said bipolar rail, and wherein each station comprises a leakage current sensor suitable to detect the existence of a leakage current between the first or the second collector shoe and the ground if the amperage of the leakage current surpasses a pre-set limit.