Anders Kullgren

The Effectiveness of Electronic Stability Control (ESC) in Reducing Real Life Crashes and Injuries

Electronic Stability Control (ESC) was introduced on the mass market in 1998. Since then, several studies showing the positive effects of ESC have been presented. Objective. In this study, data from crashes occurring in Sweden during 1998 to 2004 were used to evaluate the effectiveness of ESC on real life crashes. The effectiveness was analyzed for different road conditions, and some accident types and injury levels. Methods. The study used statistical analysis. To control for exposure, induced exposure methods were used, where ESC-sensitive to ESC-insensitive crashes and road conditions were matched in relation to cars equipped with and without ESC. Cars of similar or, in some cases, identical make and model were used to isolate the role of ESC. Results. The study shows a positive and consistent effect of ESC overall and in circumstances where the road has low friction. The overall effectiveness on all injury crash types, except rear end crashes, was 16.7 ± 9.3%, while for serious and fatal crashes; the effectiveness was 21.6 ± 12.8%. The corresponding estimates for crashes with injured car occupants were 23.0 ± 9.2% and 26.9 ± 13.9%. For serious and fatal loss-of-control type crashes on wet roads the effectiveness was 56.2 ± 23.5% and for roads covered with ice or snow the effectiveness was 49.2 ± 30.2%. It was estimated that for Sweden, with a total of 500 vehicle related deaths annually, that 80–100 fatalities could be saved annually if all cars had ESC. Conclusions. ESC was found to reduce crashes with personal injuries, especially serious and fatal injuries. The effectiveness ranged from at least 13% for car occupants in all types of crashes with serious or fatal outcome to a minimum of 35% effectiveness for single/oncoming/overtaking serious and fatal crashes on wet or icy road surface. No difference in deformation pattern was found for cars with or without ESC.

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.

The Effectiveness of ESP (Electronic Stability Program) in Reducing Real Life Accidents

ESP (Electronic Stability Program) has recently been introduced onto the market in an effort to reduce the number and severity of loss-of-control automobile accidents. This reduction is expected to be particularly evident for accidents on roads with low friction (e.g., wet or icy conditions). This study aimed to evaluate the statistical effectiveness of ESP using data from accidents that occurred in Sweden during 2000 to 2002. To control for exposure, induced exposure methods were used, where ESP-sensitive to ESP-insensitive accidents and road conditions were matched in relation to cars equipped with and without ESP. Cars of similar, or in some cases identical, make and model were used to isolate the role of ESP. As predicted, the study showed a positive effect of ESP in circumstances where road surfaces have low friction. The overall effectiveness was 22.1 (±21) percent, while for accidents on wet roads, the effectiveness increased to 31.5 (±23.4) percent. On roads covered with ice and snow, the corresponding effectiveness was 38.2 (±26.1) percent. In addition, ESP was found to be effective for three different types of cars: small front-wheel drive; large front-wheel drive; and large rear-wheel drive.

Influence of Crash Pulse Characteristics on Whiplash Associated Disorders in Rear Impacts--Crash Recording in Real Life Crashes

There are variations in rear impacts causing Whiplash Associated Disorders (WADs) which lead to short- and long-term consequences. Most rear impacts lead to no injury or to symptoms that are temporary. Impacts where the duration of symptoms differs need to be separated in analyses in order to isolate representative rear impact conditions in which more long-lasting WADs occur. The correlation between injury risk and impact severity parameters based on acceleration levels is largely unknown. Since 1995, approximately 40,000 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 66 real-life rear impacts were analyzed, where the change of velocity and the crash pulse were measured. The injury status of 94 front-seat occupants was classified as: no injury, symptoms for less than one month, symptoms for more than one month, or symptoms for more than six months after the impact. The injury risk was calculated for different duration of symptoms and grades of WAD, 0-3, correlated to the crash severity parameters. For most of the occupants that sustained symptoms for more than one month, mean acceleration was more than 4.5 g, and change of velocity higher than 15 km/h. The average mean acceleration and change of velocity for this group were 5.3 g and 20 km/h, respectively. For those occupants that sustained symptoms for less than one month, the average change of velocity was 10 km/h and the mean acceleration 3.9 g. Mean acceleration was found to be the best candidate to predict duration of symptoms compared to change of velocity and peak acceleration. There was no significant correlation between different grades of WAD and crash severity. When designing test methods for evaluating vehicle safety concerning WAD, the acceleration pulse differs considerably, depending on whether the focus is on short-term or long-term consequences.

The Risk of Whiplash Injury in the Rear Seat Compared to the Front Seat in Rear Impacts

One hundred ninety-five rear impacts with both front- and rear-seat occupants in the struck car, where at least one occupant sustained permanent disability, were selected for study. There was a significantly higher disability risk for the female rear-seat occupant compared with the male driver. Furthermore, a higher risk was found for female rear-seat occupants compared with female front-seat passengers. The disability risk for occupants of the drivers seat was three times higher for females than for males, and four times higher for females in the rear seat. In the future, test methods should consider the risk of whiplash injury in both the front and the rear seat.

The use of seat belts in cars with smart seat belt reminders--results of an observational study

Recently, smart seat belt reminders (SBR) have been introduced in cars. By increasingly reminding drivers and passengers if they are not using the seat belt, the intention is to increase the belt use to almost 100%. Objective. The objective was to study if there were differences in drivers seat belt use between cars with and without SBR. Methods. Drivers of cars with and without SBR were observed concerning seat belt use. The case (cars with SBR) and the control group (cars without SBR) were similar in all major aspects except SBR. In all, more than 3,000 drivers were observed in five cities in Sweden. Results. In cars without SBR, 82.3 percent of the drivers used the seat belt, while in cars with SBR, the seat belt use was 98.9 percent. The difference was significant. In cars with mild reminders, the use was 93.0 percent. Conclusion. It is concluded, that if the results can be generalised to the whole car population this would have a dramatic impact on the number of fatally and seriously injured car occupants.

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.

Effectiveness of Motorcycle Antilock Braking Systems (ABS) in Reducing Crashes, the First Cross-National Study

Objectives: This study set out to evaluate the effectiveness of motorcycle antilock braking systems (ABS) in reducing real-life crashes. Since the European Parliament has voted on legislation making ABS mandatory on all new motorcycles over 125 cc from 2016, the fitment rate in Europe is likely to increase in the coming years. Though previous research has focused on mostly large displacement motorcycles, this study used police reports from Spain (2006–2009), Italy (2009), and Sweden (2003–2012) in order to analyze a wide range of motorcycles, including scooters, and compare countries with different motorcycling habits. Methods: The statistical analysis used odds ratio calculations with an induced exposure approach. Previous research found that head-on crashes were the least ABS-affected crash type and was therefore used as the nonsensitive crash type for ABS in these calculations. The same motorcycle models, with and without ABS, were compared and the calculations were carried out for each country separately. Crashes involving only scooters were further analyzed. Results: The effectiveness of motorcycle ABS in reducing injury crashes ranged from 24% (95% confidence interval [CI], 12–36) in Italy to 29% (95% CI, 20–38) in Spain, and 34% (95% CI, 16–52) in Sweden. The reductions in severe and fatal crashes were even greater, at 34% (95% CI, 24–44) in Spain and 42% (95% CI, 23–61) in Sweden. The overall reductions of crashes involving ABS-equipped scooters (at least 250 cc) were 27% (95% CI, 12–42) in Italy and 22% (95% CI, 2–42) in Spain. ABS on scooters with at least a 250 cc engine reduced severe and fatal crashes by 31% (95% CI, 12–50), based on Spanish data alone. Conclusions: At this stage, there is more than sufficient scientific-based evidence to support the implementation of ABS on all motorcycles, even light ones. Further research should aim at understanding the injury mitigating effects of motorcycle ABS, possibly in combination with combined braking systems.

Risk of Permanent Medical Impairment (RPMI) in Car Crashes Correlated to Age and Gender

Objective: As fatalities from car crashes decrease, focus on medical impairment following car crashes becomes more essential. This study assessed the risk of permanent medical impairment based on car occupant injuries. The aim was to study whether the risk of permanent medical impairment differs depending on age and gender. Methods: In total, 36,744 injured occupants in car crashes that occurred between 1995 and 2010 were included. All initial injuries (n = 61,440) were classified according to the Abbreviated Injury Scale (AIS) 2005. If a car occupant still had residual symptoms 3 years after a crash, the case was classed as a permanent medical impairment. In total, 5,144 injuries led to permanent medical impairment. The data were divided into different groups according to age and gender as well as levels of permanent impairment. The risk of permanent medical impairment was established for different body regions and injury severity levels, according to the AIS. Results: The cervical spine was the body region that had the highest number of diagnoses, and occupants who sustained injuries to the upper and lower extremities had the highest risk of medical impairment for both genders. Females aged 60 and above had a higher risk of permanent medical impairment from fractures in the extremities compared to males in the same age group and younger females. Females aged 44 or younger had a higher risk of permanent medical impairment from whiplash-associated disorders (WAD) than males in the same age group. Minor and moderate injuries (AIS 1–2) had a higher risk of permanent medical impairment among older car occupants compared to younger ones. Conclusions: Differences in long-term outcome were dependent on both gender and age. Differences between age groups were generally greater than between genders. The vast majority of permanent medical impairments resulted from diagnoses with a low risk of fatality. The results emphasize the impact of age and gender in long-term consequences from car crashes. They could be used when designing safety technology in cars as well as to improve health care by contributing to better allocation of rehabilitation resources following trauma.

Influence of Seat Geometry and Seating Posture on NICmax Long-Term AIS 1 Neck Injury Predictability

Objective. Validated injury criteria are essential when developing restraints for AIS 1 neck injuries, which should protect occupants in a variety of crash situations. Such criteria have been proposed and attempts have been made to validate or disprove these. However, no criterion has yet been fully validated. The objective of this study is to evaluate the influence of seat geometry and seating posture on the NIC max long-term AIS 1 neck injury predictability by making parameter analyses on reconstructed real-life rear-end crashes with known injury outcomes. Methods. Mathematical models of the BioRID II and three car seats were used to reconstruct 79 rear-end crashes involving 110 occupants with known injury outcomes. Correlations between the NIC max values and the duration of AIS 1 neck injuries were evaluated for variations in seat geometry and seating posture. Sensitivities, specificities, positive predictive values, and negative predictive values were also calculated to evaluate the NIC max predictability. Results. Correlations between the NIC max values and the duration of AIS 1 neck injuries were found and these relations were used to establish injury risk curves for variations in seat geometry and seating posture. Sensitivities, specificities, positive predictive values, and negative predictive values showed that the NIC max predicts long-term AIS 1 neck injuries also for variations in seat geometry and seating postures. Conclusion. The NIC max can be used to predict long-term AIS 1 neck injuries.