Abstract: Driverless vehicles, confined to motion in one direction along a defined path divided into blocks, receive commands from a central unit in the form of encoded command signals radiated from an elongated radiator. Each vehicle progresses only while receiving signals regularly. The radiator comprises two parallel stretches, each extending all along the path but divided into sections, each section being as long as a block but extending across a block boundary, with a section of each stretch paired with a laterally adjacent section of the other stretch. In each section pair, the segment of one section that lies in one block is shielded, the remainder unshielded; the other section of the pair has opposite shielded and unshielded segments.