Are riders of electric two-wheelers safer than bicyclists in collisions with motor vehicles?

Electric two-wheelers (E2Ws) have become newly popular transportation tools with the associated growing traffic safety concerns. E2W riders and bicyclists behave similarly as vulnerable road users (VRUs), while exhibited dissimilarities in riding postures and interactions with the two-wheelers. Existing epidemiology reveals prominent differences in injury risks between E2W riders and other vulnerable road users in collisions with motor vehicles. The objective of this study is to investigate the factors influencing kinematics and head injury risks of two-wheeler rides in two-wheeler-vehicle collisions and compare between E2W-vehicle and bicycle-vehicle collisions. Via multi-body modeling of two two-wheeler types, two vehicle types, and three rider statures in MADYMO, twelve collision scenarios were developed. A simulation matrix considering a range of impact velocities and relative positions was performed for each scenario. A subsequent parametric analysis was conducted with focus on the kinematics and head injury risks of two-wheeler riders. Results show that the head injury risk increased with vehicle moving velocity, while the two-wheeler velocity and relative location between rider and vehicle prior to the collision exhibited highly non-linear influence on the kinematical response. The rider with larger stature had higher possibilities to miss head impact on the vehicle. In collisions with the sedan, E2W riders would sustain lower head injury risks with lower contacting velocity on the windshield than bicyclists. While in collisions with the SUV, E2W riders would sustain increasing head injury risks due to the higher structural stiffness at contact, and the risk level was about the same as bicyclists. The findings revealed the loading mechanisms behind the different head injury risks between E2W riders and bicyclists.