HEAVY-GOODS VEHICLE COLLISIONS WITH STEEL ROAD SAFETY BARRIERS: COMBINED INFLUENCES OF POSITION OF CENTER OF MASS AND TIRE-PAVEMENT FRICTION

Vehicles that collide with highway safety features do not always produce the same effects. The outcome for each vehicle that collides with a feature will be different, depending greatly not only on its mass, velocity, and impact angle but also on the position of its center of mass and on the tire-pavement friction. The ways in which barrier and striking vehicle behaviors are affected by changes in the position of the center of mass and in the tire-pavement side friction were analyzed to identify the most dangerous loading systems. Toward this aim numerous simulations of a collision of a truck against a steel road safety barrier were carried out through nonlinear, dynamic finite-element analysis. The results obtained demonstrate that the position of the center of mass is of greater consequence in collisions in which the impact energy is close to the maximum barrier containment capacity and under conditions that favor friction. The longitudinal position of the center of mass has a large impact on the risk that the vehicle will pass over the barrier or roll over. If it is in the back, the most common loading system, the risk of passing over the barrier is rather limited compared with the risk of rolling over. As the position of the center of mass is pushed forward, the risk of rolling over is reduced but the risk of passing over the barrier increases. If the height of the center of mass increases, the rollover risk is higher, but a higher center of mass does not significantly influence displacement and the risk of passing over the barrier.