Trolleybuses, by definition, use a pair of aerial wires and a trolley to draw electrical power from a remote generator. The double-wired lines and the relative trolleys, designed to contact the poles of the aerial line, present some disadvantages that up to now have greatly limited their use and diffusion. Those drawbacks can be summarized in fixed paths, landscape pollution, and complex handlings to recover the electrical contact between the trolley and the line after any interruption. The solutions described in this patent overcome those drawbacks. To supply electrical power to a trolleybus, a peculiar trolley, with two or four traverse elements collecting electrical power from a special aerial single line, is proposed. This special aerial line presents the two poles of a remote generator, periodically alternated along the single line path. Moreover, the proposed solutions suggest an application that applied to a trolleybus powered by common bifilar wire line, enhance their performances and it allows the use of existing bifilar aerial lines, saving large amounts of money.