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Dans de nombreuses mégalopoles, la progression de la part modale du vélo, par ailleurs soutenue grâce à des politiques publiques, crée un intérêt grandissant pour la sécurité des cyclistes qui représente un véritable enjeu de santé publique. La plupart des études sur le sujet utilisent des données officielles issues des forces de police. Cependant ces données sous enregistrent les cyclistes et tout particulièrement les victimes d'accidents seuls. En France, une étude menée sur le Registre médical du Rhône, quasi exhaustif en termes de chutes et de collisions à vélo, a permis d'estimer qu'un cycliste a 8 fois plus de chances d'être victime d'un accident, par heure passée sur la route, qu'un automobiliste. Cette même étude identifie un sur-risque d'accident chez les femmes. Partant de ces constats, ce travail de thèse propose une image complète de l'accidentalité à vélo qui prend en compte les facteurs d'accidents identifiés dans la littérature et propose de comprendre comment le comportement du cycliste interagit avec eux. L'objectif de nos travaux est de décrire les configurations d'accident corporel pour proposer des actions en sécurité primaire ou secondaire. Pour ce faire, nous avons mené une enquête auprès de 3337 cyclistes accidentés en 2009-2011 et identifiés dans le Registre des victimes d'accidents de la circulation du Rhône. Sur la base d'un taux important de répondants, les analyses descriptives améliorent la connaissance en accidentalité cycliste, certains facteurs d'accidents étant scrutés pour la première fois par notre enquête. A la suite des différentes analyses, le rôle du sexe du cycliste dans l'accident est apparu incertain, justifiant une étude approfondie des accidents à vélo à travers le prisme du genre. Dans un ultime volet, nous proposons un ensemble de mesures et d'idées visant l'amélioration de la sécurité des déplacements cyclistes ainsi que des perspectives de recherche en accidentalité à vélo qui combleraient les lacunes du travail proposé / In many major cities, the growing modal share of cycling, mainly supported by public policies, raises the issue of cycling safety. Most of the existing work on this topic is based on police data. However, these data underreport cyclists, especially the victims of single accidents. In France, a recent study based on the Rhône road trauma registry, a medical database covering almost all cyclist falls or collisions, considers that a cyclist is 8 times more likely to be injured than a driver by hour spend on a road. The same review also reveals an increased risk of crash for women. Based on these observations, this thesis comes up with a full picture of cycling accidents, taking into account accident factors identified in the literature. The proposed work offers a better understanding on how the cyclist’s behavior interacts with them. It aims to describe accident configurations to propose preventive primary and secondary safety actions. To do so, we surveyed 3337 cyclists injured in 2009-2011 and identified in the Rhône Road Trauma Registry. Based on a significant response rate, descriptive analyses improve existing knowledge in cycling safety, some accident factors being examined for the first time in our survey. Following these analyses, gender roles were unclear, justifying an intensive investigation on cycling accidents through the prism of gender. In order to achieve this goal, we select the 44 accidents on utilitarian trips and built a logistical regression model to explain the likelihood that the victim is a woman. All factors being equal, when a injured cyclist had a load on his bike, did not know the route, fell ascending or descending a curbside, it is more likely that the victim is a woman. Conversely, the probability for the victim to be a men increases if the cyclist’s speed is one of the accident factors. These results are confirmed and illustrated analyzing textual data on accidents stories. The last part is dedicated to a proposal of a set of actions and ideas aiming at improving cycling safety. Some research perspectives are proposed to address the weaknesses of the thesis work

Vulnerable road users (VRUs) are overrepresented in the statistics on severe and deadly injuries in traffic accidents, most commonly involving the head. The finite element (FE) method presents the possibility to model complex interactions between the human body and vehicles in order to better understand the injury mechanisms. While the rapid development of computer capacity has allowed for increasingly detailed FE-models, there is always a benefit of reducing the studied problem. Due to its material properties, the brain is more sensitive to rotational motion than to purely linear, resulting in complex injury causation. When studying brain injuries caused by a direct impact to the head, simulations using an isolated head model significantly increases efficiency compared to using a complete human body model. Also evaluation of head protective systems uses isolated mechanical head representations. It is not, however, established the extent to which the boundary conditions of the head determine the outcome of brain injuries. FE models of both the entire human body and the isolated head were used in this thesis to study the effect of the body, as well as active neck muscle tension, on brain injury outcome in VRU accidents. A pediatric neck model was also developed to enable the study of age-specific effects. A vehicle windscreen model was developed to evaluate the necessity of capturing the failure deformation during pedestrian head impacts. It was shown that the influence of the neck and body on brain injury prediction is greater in longer duration impacts, such as pedestrian head-to-windscreen impacts with an average difference of 21%. In accidents with shorter duration impacts, such as head-to-ground bicycle accidents, the average influence was between 3-12%. The influence did not consistently increase or limit the severity, and was dependent on the degree of rotation induced by the impact, as well as the mode of deformation induced in the neck. It was also shown that the predicted brain injury severity is dependent on capturing the large deformations of fractured windscreen, with the greatest effect near the windscreen frame. The pediatric neck model showed a large effect of age-dependent anatomical changes on inertial head loading, making it a promising tool to study the age-dependent effects in VRU accidents. / <p>QC 20171013</p>