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A previously developed two-dimensional model of a vehicle in a lateral roll (Rose, et al. 2008) was used in this study to analytically evaluate the effect of vehicle roll angle and roll velocity on roof-impact ΔV and consequent occupant injury mechanism and risk. Both occupants adjacent to (near-side) and remote from (far-side) the rollover’s leading side were evaluated. Injury evaluation was limited to head and neck/spinal injuries. The vehicle’s roll angle at the time of roof-impact dramatically affected the local ΔV at the point of head-to-roof contact. Both roof-rail impacts may be injurious to far-side occupants, while near-side occupants are more likely to sustain head or neck injuries in roof impacts with the adjacent roof rail. Far-side occupants have a greater risk of compressive neck injury during impacts with the remote roof rail, while adjacent roof rail impacts subject occupants to primarily lateral head impacts with a higher head injury risk.

Vehicle acceleration and compartment intrusion play major roles in occupant injury causation, in frontal offset collisions. The knowledge of injury causation may enable the injury risk to be directly assessed from accident conditions, once a relationship between accident conditions and vehicle response is known. To establish such a relationship, a simulation study was carried out, in which vehicle acceleration and local compartment intrusion were calculated for various crash speeds and overlap configurations. The simulation model was validated against crash-tests in terms of the local vehicle deformation, acceleration and local dash and toepan intrusion. It was found that average acceleration generally decreased with reduced overlap, while intrusion increased for narrower overlap and impact locations more closely to the dash and/or toepan. This general trend indicates the relatively high injury risk for near-side occupants and a low risk for far-side occupants.

This paper presents various reconstruction methods for a multiple-car-collision, resulting from one vehicle approaching a line of stationary, undamaged vehicles that consequently pushes the stationary vehicles into one another. Under these conditions, the approaching vehicle speed and delta-V of all vehicles can be estimated from the summation of all vehicles' front and rear damage plus their run-out energies. However, seldom are all vehicles available for damage inspection, or are the skid/gouge-marks or friction-coefficients adequately known. The accident severity of the collision pair of interest would be reconstructed more efficiently if the damage energy method were applied to only this collision pair. This method, however, entails the concern that the observed damage of these two vehicles has been enhanced by the subsequent collisions.

Damage analysis methods in accident reconstruction use an estimate of vehicle stiffness together with measured crush to calculate crush energy, closing speed, and vehicle delta-V. Stiffness is generally derived from barrier crash test data. The accident being reconstructed often involves one or more conditions for which vehicle stiffness is not well defined by existing crash tests. Massive moving barrier (MMB) testing is introduced as a tool to obtain additional and accident specific stiffness coefficients applicable for reconstruction. The MMB impacts a stationary vehicle of similar structure as the accident vehicle under accident-specific conditions like impact location, angle, over-ride / under-ride, offset and damage energy. A rigid or deformable structure is mounted to the front of the MMB, representative of the impacting structure in the accident. Four illustrative tests are presented.

Vehicle fleet downsizing has been discussed in Europe as an aspect to reduce fuel emissions. A recently developed mathematical model was used to study the individual effects of fleet mass distribution, impact speed reductions and inherent vehicle protection on average injury and fatality rates for downsized fleets. A baseline fleet of 700-2000 kg was downsized by a) reducing all vehicle masses by 10% or 20% and b) by removing all cars heavier than 1400 or 1200 kg. The results showed that the safety can be maintained if the vehicle masses are reduced proportionally to their original mass. A higher safety level can be achieved by removing the heavier vehicles. Traffic safety can be further enhanced by impact speed reductions or by improvements of restraint systems and vehicle compatibility.