Classified by guardrail structure
(1) Semi-rigid guardrail. The semi-rigid guardrail is a continuous beam-column structure. It absorbs collision energy and accelerates the collision process by friction between the vehicle and the guardrail, friction between the vehicle and the ground, and a certain amount of elastic and plastic deformation (mainly deformation of the guardrail system) of the vehicle, the soil foundation and the guardrail itself. The action time reduces the speed of the vehicle and forces the out-of-control vehicle to change the direction of travel and return to the normal direction of travel, thereby ensuring occupant safety and reducing vehicle damage. Semi-rigid guardrails are mainly located on sections that require a strong emphasis on occupant safety.
(2) rigid guardrail. The rigid guardrail is a substantially non-deformed guardrail structure. For rigid guardrails, the impact energy is absorbed by the change of the wheel's rotation angle, the displacement of the car body, the deformation of the car and the friction between the vehicle and the guardrail, and the vehicle and the ground. During the collision process, the degree of vehicle deformation depends on its own stiffness, collision energy and collision time. When the collision angle of the vehicle is large, it often causes more serious consequences. The rigid guardrail is mainly set on the road section that needs to strictly prevent the vehicle from getting out of the road to avoid causing secondary accidents.
(3) Flexible guardrail. The flexible guardrail is a tough guardrail structure with a large cushioning capacity. The cable guardrail is the main representative form of the flexible guardrail. It is a structure composed of several cables with initial tension applied to the column. It relies entirely on the tensile stress of the cable to resist the collision of the vehicle and absorb energy.