Abstract
Bicyclists are the most seriously injured road user in Sweden. For fatal crashes car-to-bicycle is the most common configuration and the most frequently injured body part is the head. However, the most frequent crash configuration is single-bicycle with the shoulder as the most injured body part. Shoulder injuries are non fatal but often result in long-term consequences. Shoulder-thorax-protection for bicyclists is underdeveloped. The objective of the study was to evaluate the protection provided by a conceptual airbag vest. Twenty-four car to-bicycle and eight single-bicycle crash simulations with a Human Body Model rider (SAFER HBM) were carried out, varying impact speed and impact angle. The airbag was coupled with the SAFER HBM and the shape covers the outer surface of the torso, particularly the shoulder and thorax. Shoulder peak contact force, risk of mild traumatic brain injury (mTBI), Head Injury Criterion (HIC), and the risk for two or more fractured ribs were assessed for bicyclists with and without an airbag vest. The airbag vest showed potential for shoulder protection. In single-bicycle crash simulations, a substantial reduction in shoulder contact force was observed. Additionally, the airbag vest showed potential to reduce the risk of mTBI and HIC, particularly in single-bicycle crash simulations. For all evaluated loadcases, the risk of fractured ribs remained low, both with and without the airbag vest. The detachment and position upward next to the head provided unexpected head injury protection and could be incorporated deliberately in future designs of the airbag vest. Shoulder contacts with stiff elements of the car produced the highest shoulder contact forces and biggest challenge for the airbag vest design. These contacts could be further simplified into worst-case component testing to aid the development of better protection. A tissue-based injury risk prediction is desirable as injury prediction capability of human body model need to be developed in the future. Nevertheless, the conceptual airbag vest substantially reduced loading to the shoulder and had protective effects on head and thorax.