Crash Compatibility between Roadside Infrastructure and Passenger Vehicles: Improving the Geometric and Structural Compatibility to Reduce Fatalities

Roadside accidents cause a significant number of fatalities each year in the world. To reducethis type of accident, roadside infrastructure needs to be investigated to improve protection todifferent kinds of passenger vehicles during crashes. Accident statistics have revealed ditchesand guardrails as the two main roadside safety features that reduce fatal injury risks.Guardrails were chosen for this investigation. Geometric and structural compatibility incollisions between vehicles and guardrails were studied to find ways to improve roadsidesafety. Two studies on this type of crash compatibility were conducted using the computersimulation tool LS-DYNA. Full-scale crash tests were compared with the simulation resultsfor validation.A compact car and a W-beam guardrail were chosen for a study of their interaction duringoblique collisions. The goal was to investigate the influence of vertical position and stiffnessof the main crashworthy structures in a vehicle of a constant mass during an oblique crashwith a W-beam guardrail. The simulation showed good agreement with a full-scale crash test.Using validated models, a parameter study for the geometric compatibility between passengervehicles and road barriers was carried out. This study concluded that the cross members of avehicle must be stiff. A laterally weak vehicle is likely to be more severely damaged, withhigher risk of injury. Moreover, a more deformed guardrail and a less deformed vehicle bodyare positive results, as shown by lower impact severity parameters. The influence of wheelimpacts with a post was not included in this first study.In a second study, a flared guardrail terminal was modelled and two vehicle models weremodified to simulate an oblique impact situation. The purpose of these simulations was toimprove the vehicle models, by refining their wheels and steering-suspension systems, forbetter prediction and reproduction of the vehicle behaviour in oblique collisions withguardrails. The refined front wheels and steering-suspension systems simulated better theimpact behaviour of the vehicles for the wheel-post impacts. A vehicle model needs theserefined systems to improve the analysis of oblique impacts with guardrails.With the aid of the computer simulation tool, a roadside feature can be crash analysed forvehicles under conditions that are not defined in a standard. Although only some of thesimulations have been validated, due to high costs of crash tests, the vehicle models andguardrail models presented in this thesis can contribute to further numerical studies thatsimulate other roadside collisions