First car-to-car crashes involving young adult drivers: main patterns and their relation to car and driver characteristics.

The primary objective of the study was to examine the relationship between patterns in car-to-car crashes involving young drivers and car and driver characteristics and the research design was a national register-based prospective cohort study. Individual records in a cohort born 1970-1972 are linked to road-traffic-crash data (1988-2000). Subjects' first police-registered two-car crash leading to severe or fatal injury (n = 4875) are identified. Typical crash patterns are highlighted and associations between pattern and both car and individual socio-demographic characteristics are tested. Four crash patterns are highlighted. Male drivers and those with lower educational attainment are over-represented in all patterns. Pattern-based risk levels vary considerably according to car safety level and driver's age at time of injury and socio-economic status. Crash patterns might be considered in young adult driver education systems, bearing in mind the consistent higher risks of male drivers and of drivers with lower educational attainment.

How crash severity in rear impacts influences short- and long-term consequences to the neck.

The main public-health problem concerning WAD are injuries leading to long-term consequences. Yet epidemiological studies mostly concentrate on data based on the injury outcome occurring shortly after the crash. The purpose of this article is to study the influence of crash severity in rear impacts leading to short and long-term consequences to the neck (WAD 1-3), lasting less than or more than 1 year. The influence of change of velocity as well as the car acceleration were investigated by using data from crash pulse recorders (CPR) installed in vehicles, involved in rear impacts. The influence of the car acceleration were also investigated by studying the frequency of occurrence of a tow-bar (hinge) on the struck car. Apart from real-life data, full-scale car-to-car crashes were performed to evaluate the influence of a tow-bar on the struck car. The crash tests showed that a tow-bar may significantly affect the acceleration of the car as well as that of the occupant. According to real-life crashes, a tow-bar on the struck car increased the risk of long-term consequences by 22% but did not affect the risk of short-term consequences. Out of the 28 crash recorder-equipped struck cars involving 38 occupants, 15 sustained no injury where the peak acceleration was 6g or less, 20 sustained short-term consequences where the peak acceleration was 10g or less. Three occupants from two different crashes sustained long-term consequences. The two crashes which resulted in long-term disabling neck injuries had the highest peak acceleration (15 and 13 x g), but not the highest change of velocity.

Neck injuries in frontal impacts: influence of crash pulse characteristics on injury risk.

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. The injury mechanisms in both rear-end and frontal impacts are still not known, although different hypotheses exist. Since 1992, approx. 100,000 vehicles on the Swedish market have been equipped with crash recorders to measuring frontal impacts. This paper analyses the influence of different characteristics derived from the acceleration time history on the risk of short- and long-term disability to the neck in frontal impacts. The study includes injury outcomes from 187 restrained front seat occupants in 143 frontal collisions with an overlap exceeding 25%, where the crash pulses have been recorded using crash pulse recorders. The results show that the shape of the crash pulse influences the risk of long-term disability to the neck. The vehicle accelerations in the mid and last third of the crash pulse seem to be important. It is also shown how change of velocity and mean and peak accelerations influence the neck-injury risk. It is suggested that the risk of sustaining an AIS1 neck injury in frontal impacts could be reduced by using more effective pretensioners and more advanced belt-load limiters. These results may also have implications for neck injury mechanisms in rear-end impacts.

A Study of AIS1 Neck Injury Parameters in 168 Frontal Collisions Using a Restrained Hybrid III Dummy.

The research of AIS1 neck injuries has focused on rearend collisions, but a great portion of these injuries occur in frontal impacts. AIS1 neck injuries in frontal impacts can be associated with seat belt use and it can be hypothesized that the seat belt may transfer injurious loads to the neck. This study investigates the influence of the restraint system on the neck loads by using mechanical as well as mathematical (MADYMO) models of the HIII 50(th) percentile dummy. The mathematical simulations were based on 168 frontal crash pulses collected from crash recorders, installed in passenger cars in Sweden. The neck loads were evaluated by a new neck injury criterion NIC(protraction), the upper neck flexion moment and the Nij criterion. It was found that a pretensioner, a load limiter or an airbag have the potential to reduce the neck loads below recently suggested reference values for long-term neck injuries only as well as short- plus long-term neck injuries. Moreover, the interaction between the pretensioner, the load limiter and the airbag was of great importance in order to minimize the neck loads.

Influence of Airbags and Seatbelt Pretensioners on AIS1 Neck Injuries for Belted Occupants in Frontal 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 analysed. Since 1992, approximately 150,000 vehicles on the Swedish market have been equipped with crash pulse recorders to measuring frontal impacts. This study includes results from 158 frontal impacts, where the crash pulses have been recorded using crash pulse recorders and where the status of airbag deployments was known. Only reported neck injuries, often denoted as short-term disability to the neck, were considered in this study. Injury risk functions for cars with and without airbags versus change of velocity and mean and peak accelerations were analysed. It was found that airbags in combination with seat belt pretensioners reduced the number of AIS1 neck injuries in frontal impacts with 41% +/- 15.2%. In impacts at a change of velocity between 1 and 30 km/h, airbags and pretensioners was found to reduce the neck injury risk with 59% +/- 18.6%.

Crash pulse recorder--validation in full scale crash tests.

Estimation of the accident severity is a fundamental requirement in accident reconstruction and analysis. Accident severity can be measured in many different ways, but in frontal collisions change of velocity, energy equivalent speed or equivalent barrier speed are frequently used parameters. These parameters are most often estimated from vehicle deformation. It is known, however, that the quality of these estimates is limited if compared with these obtained in laboratory test conditions. To be able to achieve almost the same measurements and measurement accuracy in real-life accidents as in the laboratory, where the acceleration time history is measured, an on-board measurement technique is required. This presentation gives results of tests of a low cost device for measuring the crash pulse for a car involved in an accident, concerning systematic and random error. The device, called the Crash Pulse Recorder (CPR), has been tested previously in several sled tests. The CPR is based on measurement of the movement of the mass in a spring mass system in a collision. A brief description of its construction is also included. The CPR is an integral part of a large accident data collection system including interior and exterior deformation measurements and evaluation of injury outcome. This report presents the results of several full-scale crash tests, undertaken to evaluate the accuracy and precision of the CPR in cars in different impact modes. The tests comprised both offset and angled collisions. Most of the tests were car to car collisions, but barrier tests were also performed. The random error of the CPR was found to be 2.2 km/hr for the delta V measurements and 0.6 g for mean acceleration.

Photogrammetry for documentation of vehicle deformations--a tool in a system for advanced accident data collection.

Vehicle deformations are important sources for information about the performance of safety systems. Photogrammetry has developed vastly under recent years. In this study modern photogrammetrical methods have been used for vehicle deformation analysis. The study describes the equipment for documentation and recording in the field (semi-metric camera), and a system for photogrammetrical measurements of the images in laboratory environment (personal computer and digitizing tablet). The material used is approximately 500 collected and measured cases. The study shows that the reliability is high and that accuracies around 15mm can be achieved even if the equipment and routines used are relatively simple. The effects of further development using video cameras for data capture and digital images for measurements are discussed.