Abstract: This present invention concerns a safety barrier that includes a boom (100) carried by a support mounting (200), associated with a drive system that is suitable for selectively moving the boom (100) between a horizontal rest position, barring the roadway in a manner that blocks passage, and a temporary position opening up the said roadway to permit the passage of traffic on the roadway when authorised access is detected, the said boom (100) being able to move in relation to the support mounting (200) when, in the rest position, it is subjected to an impact that is greater than a given threshold, so that damage is avoided, characterised by the fact that it includes elastic resources (222, 224) for the automatic return of the boom to its position (100) on the said support mounting (200).