A support system for emergency road signs, with self-locking support bracket, provided with one or more clamps (P1, P1', P1", P2, P3) which allow the rapid installation and removal thereof on and from a single-line or double-line Jersey barrier or a guardrail or a C-shaped metal pole, wherein each support bracket comprises: - at least one seat in which the post or pole of a road sign is insertable, - at least one self-locking clamp (P1 or P1' or P1" or P2 or P3) configured to be applicable to the single-line or double-line Jersey barrier or the guardrail or the C-shaped metal pole; - at least one or two grips which are integral with the main body of the support bracket, which grips allow a secure grasp of the support bracket when installing and removing it; characterized in that each self-locking clamp is provided with at least one handle operatively connected to a suitable kinematic return mechanism to actuate the rotary movement of a cam (6a or 6b), wherein said kinematic mechanism comprises a shaped post for the connection to the cam and a return spring to rotate the cam (6a or 6b) against a side surface of the Jersey barrier or guardrail or C-shaped metal pole, to keep the support bracket locked on the Jersey barrier or guardrail or C-shaped metal pole itself; wherein said shaped post is operatively connected to the handle and to the cam (6a or 6b) so as, by lifting the handle, the cam is rotated and moved away from the side surface of the Jersey barrier or guardrail or C-shaped metal pole. wherein each support bracket comprises: - at least one seat in which the post or pole of a road sign is insertable, - at least one self-locking clamp (P1 or P1' or P1" or P2 or P3) configured to be applicable to the single-line or double-line Jersey barrier or the guardrail or the C-shaped metal pole; - at least one or two grips which are integral with the main body of the support bracket, which grips allow a secure grasp of the support bracket when installing and removing it; - at least one seat in which the post or pole of a road sign is insertable, - at least one self-locking clamp (P1 or P1' or P1" or P2 or P3) configured to be applicable to the single-line or double-line Jersey barrier or the guardrail or the C-shaped metal pole; - at least one or two grips which are integral with the main body of the support bracket, which grips allow a secure grasp of the support bracket when installing and removing it; characterized in that each self-locking clamp is provided with at least one handle operatively connected to a suitable kinematic return mechanism to actuate the rotary movement of a cam (6a or 6b), wherein said kinematic mechanism comprises a shaped post for the connection to the cam and a return spring to rotate the cam (6a or 6b) against a side surface of the Jersey barrier or guardrail or C-shaped metal pole, to keep the support bracket locked on the Jersey barrier or guardrail or C-shaped metal pole itself; wherein said shaped post is operatively connected to the handle and to the cam (6a or 6b) so as, by lifting the handle, the cam is rotated and moved away from the side surface of the Jersey barrier or guardrail or C-shaped metal pole. <EOS>