Assessing bicycle helmet protection for head and neck in E-scooter falls

The rapid increase in E-scooter usage has led to more scooter-related head and neck injuries. Yet, experimental data on head impacts and helmet effectiveness during crashes are scarce. The objectives of this study are to experimentally evaluate bicycle helmets in E-scooter falls, assessing head kinematics, impact conditions, and injury risks in two crash scenarios with and without helmets.

Six E-scooter forward falls, induced by a curb collision at 20 km/h, were simulated in sled tests using a Hybrid III 50th anthropomorphic test device with and without a helmet. The curb was positioned either perpendicularly or at a 55° angle to the E-scooter's trajectory. Head velocity, head acceleration, neck load, chest acceleration, and chest deflection were measured.

The average normal and tangential head velocities at impact were 5.9 m/s and 3.7 m/s, respectively. In configurations without helmet, both head accelerations and neck loads exceeded some injury thresholds, indicating a risk of severe injury. Using a helmet significantly reduced peak head linear (143 g vs. 571 g) and rotational (9.8 krad/s² vs. 23.1 krad/s²) accelerations, and Head Injury Criterion (HIC) (792 vs. 5868). However, it did not significantly affect peak head rotational velocity (44.5 rad/s vs. 41.5 rad/s), neck load (in flexion-compression) nor Neck Injury Criterion (NIJ) (1.2 vs. 1.0).

The bicycle helmet significantly reduced most head injury metrics. Yet, the risk of severe head and neck injuries remains high. These results offer valuable data for evaluating head protection and developing and validating numerical crash test reconstructions for further investigations.