Road safety performance of a new W-beam guardrail system with rubber sandwich layer under vehicle collisions: Experimental and numerical studies

The W-beam guardrail is widely employed as a roadside safety barrier to absorb impact energy, minimize occupant risk and redirect vehicles back onto the road, enhancing highway traffic safety. This study introduces an innovative W-beam guardrail equipped with a rubber sandwich layer aimed at improving safety performance. The impact resistance of this new guardrail was evaluated through both experiments and finite element (FE) analysis. Six W-beam guardrails with a rubber sandwich layer were manufactured and tested using a drop-hammer impact device under different impact energies, rubber thicknesses and hammer shapes. The dynamic responses of the guardrail, including impact force, mid-span deflection and failure mode, were obtained. Under drop-hammer impact, the guardrail primarily exhibited global deformation along with localized denting at the point of impact. The rubber layer plays an important role in energy absorption. Additionally, FE models of the new guardrail were established and validated against experimental results. Using the validated model, a 48-meter-long guardrail system and vehicle model were established to analyze the performance of the new W-beam guardrail system under vehicle collision. The numerical results indicate that the guardrail system with a rubber sandwich layer effectively reduces the maximum lateral displacement and helps redirect the vehicle's trajectory. Both the occupant impact velocity (OIV) and occupant ridedown acceleration (ORA) comply with the JTG B05–01 standard. Furthermore, the redirecting capacity of the new guardrail and occupant safety were evaluated, considering various parameters such as vehicle velocity, W-beam rail plate thickness, and rubber layer thickness, to determine the promising guardrail configuration within the studied parameter range.