Abstract
Traditionally, in the field of utility vehicles, the improvements in passive safety has been focused towards the protection of occupants in frontal collisions. However, there are other configurations of collisions with these vehicles involved that present important injury severity. Between these it is noticeable the rollover of those vehicles, because of these types of accident, though they represent a low percentage of the cases (6 % of the accidents in Spain present any kind of rollover) cause an injury severity proportionally much greater than any other configuration (approximately 4 times greater).
Currently there are researches related with passenger cars rollovers, statistical studies and in-depth accident studies, although it is a field not sufficiently developed. In fact, excepting the U.S. FMVSS Standards relating to rollover and roof resistance (Standards that when applied they do not simulate the real rollover dynamics realistically), there are not international standards focused towards the improvement of these vehicles when they suffer these kind of accidents. In this work several accident databases have been analysed, Spanish and American, with a double objective. In one hand an statistical analysis has been carried out comparing rollover accidents with the rest of configurations, and studying the weight of different factors that can have influence in injury severity of the occupants in this type of accident, such as the area in which the accident has happened, the use of restraint systems, the position in the vehicle, age or sex of the occupants. On the other hand injury mechanisms have been analysed, specially those related to occupant ejections and location of injuries. While in this type of accidents the injuries are located mainly in head, face and neck (directly due to roof collapse during rollover), ejection is a typical injury mechanism in these events and causes an enormous injury severity (in Spain, around 90 % of ejected occupants in rural rollovers dies or suffers severe injuries). The ejection frequency increases significantly in those occupants who do not use seat belt. Current restraint systems are not designed properly to reduce the severity of injuries during rollover, for which it is suggested the necessity of developing a device that protects those body regions mainly exposed in this configuration of accident, and its application to the general improvement of the occupant restraint. Additionally it has been evaluated the cost of the casualties and severely injured occupants in rollover accidents in Spain along 1999 (according to COST 313 procedure). The conclusion reached is that, despite of the low frequency of this kind of accidents, the hospitable, social and personal costs are very significant.