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 reduce\nthis type of accident, roadside infrastructure needs to be investigated to improve protection to\ndifferent kinds of passenger vehicles during crashes. Accident statistics have revealed ditches\nand guardrails as the two main roadside safety features that reduce fatal injury risks.\nGuardrails were chosen for this investigation. Geometric and structural compatibility in\ncollisions between vehicles and guardrails were studied to find ways to improve roadside\nsafety. Two studies on this type of crash compatibility were conducted using the computer\nsimulation tool LS-DYNA. Full-scale crash tests were compared with the simulation results\nfor validation.\n\nA compact car and a W-beam guardrail were chosen for a study of their interaction during\noblique collisions. The goal was to investigate the influence of vertical position and stiffness\nof the main crashworthy structures in a vehicle of a constant mass during an oblique crash\nwith a W-beam guardrail. The simulation showed good agreement with a full-scale crash test.\nUsing validated models, a parameter study for the geometric compatibility between passenger\nvehicles and road barriers was carried out. This study concluded that the cross members of a\nvehicle must be stiff. A laterally weak vehicle is likely to be more severely damaged, with\nhigher risk of injury. Moreover, a more deformed guardrail and a less deformed vehicle body\nare positive results, as shown by lower impact severity parameters. The influence of wheel\nimpacts with a post was not included in this first study.\n\nIn a second study, a flared guardrail terminal was modelled and two vehicle models were\nmodified to simulate an oblique impact situation. The purpose of these simulations was to\nimprove the vehicle models, by refining their wheels and steering-suspension systems, for\nbetter prediction and reproduction of the vehicle behaviour in oblique collisions with\nguardrails. The refined front wheels and steering-suspension systems simulated better the\nimpact behaviour of the vehicles for the wheel-post impacts. A vehicle model needs these\nrefined systems to improve the analysis of oblique impacts with guardrails.\n\nWith the aid of the computer simulation tool, a roadside feature can be crash analysed for\nvehicles under conditions that are not defined in a standard. Although only some of the\nsimulations have been validated, due to high costs of crash tests, the vehicle models and\nguardrail models presented in this thesis can contribute to further numerical studies that\nsimulate other roadside collisions.