Examination of Crash Injury Risk as a Function of Occupant Demographics.

The objectives of this study were to provide insights on how injury risk is influenced by occupant demographics such as sex, age, and size; and to quantify differences within the context of commonly-occurring real-world crashes. The analyses were confined to either single-event collisions or collisions that were judged to be well-defined based on the absence of any significant secondary impacts. These analyses, including both logistic regression and descriptive statistics, were conducted using the Crash Investigation Sampling System for calendar years 2017 to 2021. In the case of occupant sex, the findings agree with those of many recent investigations that have attempted to quantify the circumstances in which females show elevated rates of injury relative to their male counterparts given the same level bodily insult. This study, like others, provides evidence of certain female-specific injuries. The most problematic of these are AIS 2+ and AIS 3+ upper-extremity and lower-extremity injuries. These are among the most frequently observed injuries for females, and their incidence is consistently greater than for males. Overall, the odds of females sustaining MAIS 3+ (or fatality) are 4.5% higher than the odds for males, while the odds of females sustaining MAIS 2+ (or fatality) are 33.9% higher than those for males. The analyses highlight the need to carefully control for both the vehicle occupied, and the other involved vehicle, when calculating risk ratios by occupant sex. Female driver preferences in terms of vehicle class/size differ significantly from those of males, with females favoring smaller, lighter vehicles.

Side Impact Regulatory Trends, Crash Environment and Injury Risk in the USA.

Light duty vehicles in the US are designed to meet and exceed regulatory standards, self-imposed industry agreements and safety rating tests conducted by NHTSA and IIHS. The evolution of side impact regulation in the US from 1973 to 2015 is discussed in the paper along with two key industry agreements in 2003 affecting design of restraint systems and structures for side impact protection. A combination of all the above influences shows that vehicles in the US are being designed to more demanding and comprehensive requirements than in any other region of the world. The crash environment in the US related to side impacts was defined based on data in the nationally representative crash database NASS. Crash environment factors, including the distribution of cars, light trucks and vans (LTV's), and medium-to-heavy vehicles (MHV's) in the fleet, and the frequency of their interactions with one another in side impacts, were considered. Other factors like, crash severity in terms of closing velocity between two vehicles involved in crash, gender and age of involved drivers in two-vehicle and single vehicle crashes, were also examined. Injury risks in side impacts to drivers and passengers were determined in various circumstances such as near-side, far-side, and single vehicle crashes as a function of crash severity, in terms of estimated closing speed or lateral delta-V. Also injury risks in different pairs of striking and struck cars and LTV's, were estimated. A logistic regression model for studying injury risks in two vehicle crashes was developed. The risk factors included in the model include case and striking vehicles, consisting of cars, SUV's, vans, and pickup trucks, delta-V, damage extent, occupant proximity to the impact side, age and gender of the occupant, and belt use. Results show that car occupants make up the vast majority of serious-to-fatally injured occupants. Injury rates of car occupants in two-vehicle collision are highest when the car is struck by a pickup and lowest when struck by a car. This was the case across all lateral delta-V ranges. Additionally, near-side injury rates are substantially higher than those in far-side impacts.

Effects of booster seat laws on injury risk among children in crashes.

OBJECTIVE: Belt-positioning booster seats have been shown to reduce injury risk among child passengers aged 4 to 8 in motor vehicle crashes. To encourage the use of booster seats, many states have enacted laws that require the use of either a child restraint with internal harness or a belt-positioning booster seat, but the specific age range covered by the laws varies by state. Previous studies have found evidence that booster seat laws are effective in reducing injury risk among children, but these studies primarily have included states with younger age requirements (e.g., ages 4-6) for booster seats. The objective of the present study was to examine the effectiveness of booster seat laws in several states that cover children through age 7 or 8. METHODS: Police-reported crash data from 5 states--Missouri, North Carolina, Pennsylvania, Wisconsin, and Wyoming--were used to compare population-based injury rates, restraint use, and seating position among children before and after booster seat laws. The pre-law period was comprised of the 2 calendar years prior to the year of enactment of the booster seat law, and the post-law period was comprised of the 2 calendar years after the year of the effective start of the booster seat law. Effectiveness estimates were adjusted using a comparison group of children aged 9 to 12 in the same states who were not covered by the booster seat laws. RESULTS: Among children in crashes who were affected by law changes in the 5 study states, the per capita rate of children using child safety seats (either a harnessed child restraint or booster seat) increased nearly 3 times, and the per capita rate of children riding in rear seats increased 6 percent after the booster seat laws were implemented. Booster seat laws were associated with a 5 percent reduction in the per capita rate of children who sustained injuries of any severity and a 17 percent reduction in the per capita rate of children who sustained fatal or incapacitating injuries. CONCLUSIONS: Results provide evidence that booster seat laws are effective in increasing the use of child safety seats, increasing the placement of children in rear seats, and reducing injuries, especially severe injuries, among children covered by the laws.

A study of the effectiveness of Electronic Stability Control in Canada.

Electronic Stability Control (ESC) is a crash avoidance system found on many vehicles. Unlike air bags, which only help during a collision, ESC helps to avoid a loss of control that could lead to a collision by preventing skidding. ESC is designed to help the driver stay in control of the vehicle during an emergency manoeuvre, such as when the driver needs to swerve to avoid an obstacle. Our study is an effectiveness evaluation of ESC using crash data. The purpose of a Canadian evaluation study is to examine whether there is an issue with multi-vehicle crashes, and whether ESC is effective in Canadian weather conditions, i.e. on ice, snow and slush. Our results show that ESC is effective for all ESC-sensitive crashes (41.1% effectiveness) and its effectiveness is higher for ESC-sensitive injury crashes only (54.8% effectiveness). In particular, ESC is effective in the case of all multi-vehicle ESC-sensitive crashes (23.2% effectiveness) and of multi-vehicle ESC-sensitive injury crashes (28.4% effectiveness). ESC is also effective for single-vehicle ESC-sensitive crashes, both for all severities of crashes (18.6% effectiveness) and injury crashes only (49.3% effectiveness). The results of the study also show that ESC is effective in Canadian weather conditions (i.e. on ice, snow and slush). The effectiveness of ESC on roads covered with ice, snow and slush is 51.1% for ESC-sensitive crashes of all severities and 71.1% for ESC-sensitive injury crashes. ESC is also effective on dry roads (36.3% effectiveness for ESC-sensitive crashes of all severities and 46.6% effectiveness for ESC-sensitive injury crashes), wet roads (35.8% effectiveness for ESC-sensitive crashes of all severities and 49.5% effectiveness for ESC-sensitive injury crashes) and for both cars (28.5% effectiveness for ESC-sensitive crashes of all severities and 43.7% effectiveness for ESC-sensitive injury crashes) and LTVs (51.9% effectiveness for ESC-sensitive crashes of all severities and 69.6% effectiveness for ESC-sensitive injury crashes).

Safety impacts due to the incompatibility of SUVs, minivans, and pickup trucks in two-vehicle collisions.

This research sets out to estimate the effects of vehicle incompatibility on the risk of death or major injury to drivers involved in two-vehicle collisions. Based on data for 2,999,395 drivers, logistic regression was used to model the risk of driver death or major injury (defined has being hospitalized). Our analyses show that pickup trucks, minivans and sport utility vehicles (SUVs) are more aggressive than cars for the driver of the other vehicle and more protective for their own drivers. The effect of the pickups is more pronounced in terms of aggressivity. The point estimates are comparable to those in the Toy and Hammitt study [Toy, E.L., Hammitt, J.K., 2003. Safety impacts of SUVs, minivans, and pickup trucks in two-vehicle crashes. Risk Analysis 23, 641-650], but, in contrast to that study, we are now able to establish that a greater number of these effects are statistically significant with a larger sample size. Like vehicle mass and type, other characteristics of drivers and the circumstances of the collision influence the driver's condition after impact. Male drivers, older drivers, drivers who are not wearing safety belts, collisions occurring in a higher speed zone and head-on collisions significantly increase the risk of death. Except for the driver's sex, all of these categories are also associated with an increased risk of death or of being hospitalized after being involved in a two-vehicle collision. For this risk, a significant increase is associated with female drivers.