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The problem of incompatibility between different car types has become an important issue in the society. In two- car crashes, the aggressivity to the other vehicles is a factor often mentioned. In this study aggressivity is defined as the influence on injury outcome in the other vehicle due to differences in car structure and mass of the studied vehicle. The study was based on police-reported two-car collisions in Sweden. The influence of car mass and structure on driver relative injury risk was for some vehicle categories analyzed with a new developed technique where the influence of mass and structure was separated. SUVs were found to have 32% higher mass factor and 23% higher structural aggressivity factor than the average value, resulting in a 62% higher total aggressivity factor than the average.

The European crash test program, Euro NCAP, has since its launch presented results of some 80 individual car models. The improvements in the general level of protection have been substantial. While the intention of the test program is to stimulate the use of best practice, and not to predict real-life outcome, it is nevertheless important to validate the positive development, and to pinpoint potential areas not included in the laboratory safety ratings. In this study, Euro NCAP rating results were compared with a comprehensive car model safety rating method based on real-life crashes, developed by Folksam. In addition, correlation with relative injury risks was also studied. In the Folksam method, the ratings are based on the risk of fatalities and long-term consequences due to injury. The car models were grouped together according to the Euro NCAP star ratings.

AIS 1 neck injuries has become the most common disabling injury in vehicle crashes. Research has shown that there are variations in rear impacts causing short- and long-term disability to the neck. Therefore impacts in where the duration of symptoms differ need to be separated in analyses. Crash severity is usually measured as change of velocity. The correlation between injury risk and impact severity parameters based on acceleration levels is to a high extent unknown. Since 1995, approx. 15,000 vehicles on the Swedish market have been equipped with crash pulse recorders measuring the acceleration time history in rear impacts. In the present study, the results from crash recording of 34 real life rear impacts were analysed where the change of velocity and the crash pulse were measured. The injury status of the 49 front occupants was classified as no symptoms, or symptoms less or more than 1 month after the impact.

In the development of a crashworthy road transport system, guard-rails could play an important role in preventing frontal collisions on roads without separated lanes and in avoiding collisions with roadside objects. Crash pulses in crashes into guard rails may differ from e.g. car-to-car collisions, concerning the duration and mean acceleration. If the characteristics of crash pulses into guard-rails differ from those used in the design of vehicle interior restraint systems, it may influence the performance of these systems.. Collisions with soft guardrails, such as wire ropes, may often have pulse duration of 200 ms or more. The performance of e.g. airbag systems in collisions with such duration is rarely studied. This study presents the results of six crash tests, carried out with identical vehicles running into three types of guard rails at two different test speeds, 80 and 110 km/h, and at two different impact angles, 45° and 20° respectively.

Dummy responses in a crash test can vary depending not only on the change of velocity but also on how the impact was generated. Literature reporting how acceleration pulses can vary in cars impacted in different configurations is limited. The aim of this study was to collect and categorise different acceleration pulses in 3 different types of rear collision. The acceleration pulse resulting from a solid, 1000 kg, mobile barrier test at 40% overlap and an impact velocity of 15 km/h was studied for 33 different cars. Seven cars were impacted at 100% overlap at higher impact velocities using the same mobile barrier. Acceleration pulses from two different car types in real-world collisions producing a similar change of velocity were also analysed. The results from the barrier tests show that a similar change of velocity can be generated by a large variety of pulse shapes in low velocity rear impacts.

AIS1 neck injuries are the most frequent disabling injuries among car occupants in road traffic accidents. Although neck injury is mostly regarded as resulting from rear end collisions, almost one third of all neck injuries occur in frontal impacts. Several studies have shown the effect of airbags on injury and fatality rates. However, studies of the effect of airbags on the risk of injuries to different body regions are rare. Airbags and seatbelt pretensioners may influence especially the risk of neck injuries. This paper presents influence of airbags and pretensioners on reported neck injury risk in frontal impacts. Cars fitted with airbags in combination with pretensioners and cars without have been analyzed. Since 1992, approximately 150,000 vehicles on the Swedish market have been equipped with crash pulse recorders to measuring frontal impacts.

Pedestrians and bicyclists account for a significant share of deaths and serious injuries in the road transport system. The protection of pedestrians in car-to-pedestrian crashes has therefore been addressed by friendlier car fronts and since 1997, the European New Car Assessment Program (Euro NCAP) has assessed the level of protection for most car models available in Europe. In the current study, Euro NCAP pedestrian scoring was compared with real-life injury outcomes in car-to-pedestrian and car-to-bicyclist crashes occurring in Sweden. Approximately 1200 injured pedestrians and 2000 injured bicyclists were included in the study. Groups of cars with low, medium and high pedestrian scores were compared with respect to pedestrian injury severity on the Maximum Abbreviated Injury Scale (MAIS)-level and risk of permanent medical impairment (RPMI). Significant injury reductions to both pedestrians and bicyclists were found between low and high performing cars.

In the design of a safe road transport system there is a need to better understand the safety challenges lying ahead. One way of doing that is to evaluate safety technology with retrospective analysis of crashes. However, by using retrospective data there is the risk of adapting safety innovations to scenarios irrelevant in the future. Also, challenges arise as safety interventions do not act alone but are rather interacting components in a complex road transport system. The objective of this study was therefore to facilitate the prioritizing of road safety measures by developing and applying a new method to consider possible impact of future vehicle safety technology. The key point was to project the chain of events leading to a crash today into the crashes for a given time in the future. Assumptions on implementation on safety technologies were made and these assumptions were applied on the crashes of today.