Abstract: A vehicle-mounted device for positioning traffic cones (14) on the street and for collecting them from the street. Each cone has a conical hollow body (15) and a base (16). The cones are stacked and nested in a supply (8) comprising a hollow vertical body open at least at its base (28) to permit the reception of the base (16) of a cone. A platform (4) is disposed about a vertical axis (10) and disposed below the base (28) of the supply (8). The platform (4) has at least one opening (6) and a fork formed of two fingers (7) which are substantially horizontal and are spaced from each other in a direction radially of the platform so as to let pass only the body (15) of a cone and not the base (16) of the cone.