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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.

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.

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 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.

Nygren(1) showed that whiplash injuries in rear-end collisions often lead to permanent disability. Ten percent of those initially complaining about neck pain after a rear-end collision had remaining problems 5 years after the accident and were judged as permanently, medically disabled. It was also shown that fitted headrests had little effect in preventing whiplash injuries. Fixed headrests reduced the incidence of whiplash injuries by 24 percent, while adjustable headrests reduced the risk by only 14 percent. The results of whiplash injuries in terms of permanent disability were not affected by headrest fitting and type. The present study is based on 339,675 accidents and determines if the variations of the effects of headrests in different car models could be explained by their type and position.

This paper investigates the issue of geometric incompatibility between vehicles involved in T-bone side impact crashes. Some illustrative examples and case histories are presented that clearly demonstrate how a bullet vehicle, with a high front bumper region and a raised bonnet with a very stiff facia, intrudes significantly into the soft section of a sedan shaped car resulting in sever head and chest trauma. Experimental results of two T-bone crash tests: a sedan car into a sedan car and a Four Wheel Drive (4WD) vehicle into a sedan car are described. The paper also presents a MADYMO simulation of a tram impacting the side of a car demonstrating how head strike of the struck vehicle’s near side occupant can result in severe head injury at speeds as low as 35 km/h. The authors conclude with some discussion of how the front of vehicles should be designed so as to eliminate the possibility of sever intrusion and head strike in such crashes.

The safety situation in Sweden has improved the last decade but the positive trend has levelled out the last few years. The parliament has taken interest in the problem and has formulated the “Vision Zero” as a new strategy. The Vision Zero claims that it is not acceptable to have fatalities and injuries leading to long-term problem in the road transport system. The government has further focussed the work by a special 11-point program for traffic safety and an investigation how to establish legislation giving all system designers larger responsibility for the safety level in the road transport system. New better knowledge is needed to support the new strategy. Changing the focus from accidents to preventing severe injuries will help to solve the problem. More co-operations between the various traffic safety disciplines are urged for in the design of a crashworthy road transport system, where vehicles, infrastructure, speed and human failures are handled simultaneously.

Even though child restraint systems (CRS) are very effective there are still serious problems because of non-use or misuse. This is often due to the fact that the installation of the CRS in the cars is difficult, complicated and unstable. A standardised interface between the CRS and the car seat would solve these problems. Within the IS0 Committee ISO/TC22/SC12NVGl this item has been raised and several proposals for an “ISOFIX have been discussed. Apart from the installation aspects, other features e.g. disconnection of passenger airbags can be included in the system. Several concepts called ISOFlX type 1 to 7 with different working names e.g. DELTAFIX, EASY-FIX, MONOFIX and UNlFlX have been evaluated. The handling performance of some of the prototypes have been tested by customer evaluation with very positive results. Crash performance has also been investigated. The paper will give an update on the latest progress of this development, including a preliminary specification.

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.

Injury rating is an important issue in the field of traffic safety. The injury pattern can be obtained either from the scene of the accident, including all severity grades, or from the frequency of those fatally injured. Less attention has been paid to the long-term consequences of an injury. Furthermore, the existing rating system is based on the medical status at the scene of the accident or immediately after and judges only the risk of death. Nygren showed that for many body regions the AIS values did not reflect the outcome of a trauma expressed in permanent medical disability. In this study, 339,675 accidents with private cars were analyzed with respect to injuries to car occupants. In these accidents, 14,361 persons were injured. The risk of permanent disability due to different injuries is derived and linked to AIS values to different body regions. A rating system for injuries based on the risk of death or permanent disability is proposed.

This paper presented a part of results from an ongoing project for pedestrian protection, which is carried out at Chalmers University of Technology in Sweden. A validated pedestrian mathematical model was used in this study to simulate vehicle-pedestrian impacts. A large number of simulations have been carried out with various parameters. The injury-related parameters concerning head, chest, pelvis and lower extremities were calculated to evaluate the effect of impact speed and vehicle front structure on the risk of pedestrian injuries. The effect of following vehicle parameters was studied: stiffness of bumper, hood edge, hood top, windscreen frame, and shape of vehicle front structures. A parameter study was conducted by modelling vehicle-pedestrian impacts with various sizes of cars, mini vans, and light trucks. This choice represents the trends of new vehicle fleet and their frequency of involvement in real world accidents.

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.

Injuries to motorcyclists lead to permanent disability more often than injuries to car occupants (10 percent versus 6 percent). The use of helmets has decreased the risk of head injuries. Other injuries leading to permanent disability are currently concentrated on the extremities (about 70 percent). Almost all are due to fractures located in joints where knees, elbows, shoulders, and ankles are the modest common spots. In a study based on 200 motorcycle accidents, it was shown the existing protective clothing had no effect on the incidence of fractures to knees, elbows, and shoulders. Based on that knowledge, a new motorcycle suit was constructed. The main goal was to find a shock-absorbing material to protect knees, elbows, and shoulders in an accident. Confor Foam, a medium-density urethane foam, was tested and found to possess relevant characteristics.