OBJECTIVE:In Europe, Powered Two-Wheelers (PTW) riders are involved in 15% of all traffic fatalities and the most serious injuries are sustained on the trunk and the head. The aim of this work is to study motorcyclist impact conditions through the reconstruction of 8 real accidents leading to AIS3+ trunk injuries. METHODS:Based on multi-body simulations, key parameters such as impact speed, body impact angles and impacted obstacles are deeply analyzed to determine their influence on injury severity. RESULTS:Oblique and lateral impacts tend to increase the risk of rib fractures. Trunk impacts against vehicles show predominant normal speed components (25-40 km/h), while impacts with the ground have higher tangential speeds (40-50 km/h). Two main impact configurations for the trunk are proposed to reproduce impact conditions during PTW accidents causing AIS3+ trunk injuries. CONCLUSION:This study allows a better understanding of trunk injury mechanisms in PTW accidents and can be used to improve protective device design.

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Introduction: The recent increase in the use of bicycles and personal mobility devices (PMDs), including mostly E-scooters, is associated with a rapid rise in injuries. Understanding the main crash scenarios leading to these injuries is essential to evaluate and improve preventive and protective measures, especially for PMDs, which are often equated with bicycles. The objective of this study is to identify and compare the most common two-party collision scenarios for bicycles and PMDs, and to identify factors affecting injury severity. Method: Crashes involving at least one PMD or one bicycle and another road user were analyzed from the 2019-2022 French police-reported road crashes database. We investigated the rider, the other vehicle, the road, and the crash scenarios characteristics (pre-crash maneuvers, impact zone on vehicles) and their joint effect on injury severity (hospitalization or fatality: yes/no). Results: We included 16,302 bicycle crashes and 4,118 PMD crashes in the analysis. Most of these collisions (75%) were against a car. The most frequent and the most severe collision scenario was the side-on-head for both bicycles (51%) and PMDs (58%); 67% of both bicycles and PMDs were going straight before the collision. Main factors associated with increased injury severity included colliding with a greater size vehicle, age above 50, and riding on roads with a higher speed limit. Bicycles remained at a higher risk of severe injury than PMDs after accounting for adjustment factors. Conclusions: Although collision scenarios appear similar for bicycles and PMDs, differences in other crash characteristics and injury severity suggest that these two modes of transportation should not be equated in crash investigations. Practical implications: These findings emphasize the need to primarily investigate side-on-head collisions with a moving car for both PMDs and bicycles in order to develop, evaluate, and improve protective devices to reduce the risk of injuries.

A method to evaluate the effectiveness of wearable airbag protectors for motorcyclists is proposed in this work. The mitigation of thoracic injury severity in relevant accident conditions was investigated by a multimodel numerical approach. A set of impact conditions, obtained from previous work using multibody models, was used as input data to support the detailed analysis of injury risk with finite element models. The HUMOS II human model and an airbag model were validated from experimental data and coupled to evaluate the performance of the protector. Multiple frontal thoracic impact conditions were simulated on the human model by testing the airbag protector and reference simulations without any protection. A reduction on the skeletal AIS score of 1 was obtained, while the probability of sustaining severe soft tissue injuries was reduced by up to 22% with the safety device. Impact velocity and impactor shape were identified as relevant injury risk factors.

Motorcycle accidents lead to a high rate of traffic mortality and morbidity. While helmet development and mandatory wearing have reduced head injuries, little progress has been made regarding trunk protection. Wearable airbag devices represent a promising solution to prevent trunk injuries. Nevertheless, research investigations need to be performed to assess and optimise the efficiency of such devices. This work consisted in the analysis of motorcyclist trunk impact conditions involved in various crash configurations to provide critical information in order to evaluate and improve the performances of airbag devices. First, an epidemiological and an accidentological analysis of data collection related to 252 real accidents, focusing on victims admitted into the shock rooms of two French trauma centres were performed. The data obtained was combined with numerical multibody parametric investigations, allowing the reproduction of 240 accident situations. An original and representative analysis of motorcyclists' impact conditions was provided, weighting the numerical study output data according to the real accident database. The impacted regions of the human body, the impact velocity and the accident chronology obtained in this work made it possible to define critical information for airbag efficiency assessment: the zones and levels of protection, the impacted surfaces as well as the airbag intervention time and the duration of maintained inflation of the airbag.