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Road accident risk assessment is a complex topic due to the large number of factors determining it and to the difficulties to collect data. In addition, most exposure factors influencing crash probability, such as environment and driver characteristics, are dependent on each other, so that it is not intuitive to devise a cause-effect scenario. The use of telematics devices, recently spreading among insurance and rental companies, provides new chances to collect exposure data, to define interpretive models of accident risk, and to explain variables relationships. Using global positioning system (GPS) data available through a long term rental company, the authors studied a sample of 900 vehicles. The authors aggregated raw data (e.g., road type covered, time, speed) in exposure metrics and organized them in a relational database. The authors built a number of multivariate logistic regression models, adopting a strategy to progressively refine them. The authors obtained a relatively high model fits (up to pseudo R2 0.301, Hosmer-Lemeshow p value 0.206) acquiring insights about the nonlinear association between explanatory variables and their outcomes. Interactions between variables were also examined. The results are, in general, in accordance with similar studies; regarding certain observed discrepancies, a discussion is provided to explain their origin, starting from the differences in associating predictors, outcome and interaction variables. [ABSTRACT FROM AUTHOR]

Existing roadside barriers generally pose a risk for motorcyclist impacts against them; therefore several devices exist and are intended to mitigate the effects of such impacts. The purpose of the study is to investigate the influence of some impact parameters on device behaviour. A numerical crash scenario, according to UNE135900:2008, was built and the effects of three different biker protection devices were simulated. Numerical models were set up and validated against real test data. A simulation campaign was performed investigating the influence of approach angle and speed. Results showed that injury indexes registered by the dummy during the impact rise as approach angle or speed rises. A regression analysis was carried out and the relationship between impact severity, represented by injury indexes, and both the investigated impact parameters proved to be quadratic. An explicative theory is proposed, pointing at that part of kinetic energy that is associated with the component of approach speed orthogonal to the barrier as the most influent parameter on the device performance. [ABSTRACT FROM PUBLISHER]