A method secures a host vehicle circulating on a traffic lane of a road infrastructure including at least one lane adjacent to the traffic lane. The securing method includes, for each adjacent lane: detecting a plurality of vehicles present on the adjacent lane, including an estimate of at least one information item relating to each detected vehicle, including the speed; determining, with the detected vehicles forming a flow of vehicles, a value representing the speed of the flow on the adjacent lane, for example, the average speed; comparing the speed of the host vehicle with the value representing the speed of the flow of vehicles on the adjacent lane; and, if the speed of the host vehicle is greater than a predetermined threshold at the value representing the speed of the flow of vehicles on the adjacent lane, detecting a hazardous situation for the host vehicle.