Safety performance evaluation of two-waves and Three-waves W-beam guardrails using finite element simulation

Due to the limitation of testing equipment on performing in-situ crash tests on the road barriers in the country (Iran) to evaluate the actual performance of the barriers, this study has been conducted with the aid of LS-DYNA software. Two- waves and three-waves W-beam guardrails, concrete barrier and cable barrier have been simulated by defining proper materials and modeling in detail and their safety performance was evaluated under conditions of MASH Test Level 3 requirements. Furthermore, by creating changes in geometry of the performed guardrails in Iran by considering similar cases in AASHTO roadside design guide, in this study the guardrail and vehicle's behavioral parameters in collision with vehicle was easily compared. By considering the criteria of the MASH, two-waves guardrail with U-shape Post, could not successfully redirect the errant vehicle. On the other hand, three-waves guardrail, concrete barrier, cable barrier and also the modified G4(1s) had acceptable performance in preventing the vehicle to penetrate into guardrail back face or overriding the installation. Based on the findings of this study, computer simulations demonstrate an unsuccessful performance of two-waves guardrail used in Iran to meet the requirement of test Level 3 criteria (TL3) in MASH (the main criteria in evaluating of highway safety features) which is the most often used crash test all around the world and according to the fact that the successful performance of road guard to meet these requirements is the required criterion for its usage in urban highways (allowed speed is between 100-110 km/h). More investigations, particularly, performing in-situ crash tests - as a primary means of assessing roadside safety features - are required.