Investigation on Contralateral Lower Extremity Injuries of Pedestrian and E-Bike Rider Based on C-NCAP

Lower extremities are easily injured in traffic accidents. During pedestrian-vehicle crashes, pedestrian lower extremities are subjected to the influence of combined shear force and bending force, which could bring about ligament tear and bone fracture. According to 2018 China New Car Assessment Program (C-NCAP) pedestrian testing protocol, where the flexible pedestrian legform impactor (FLEX-PLI) is struck from the right lateral by vehicle, the injuries of the ipsilateral side leg are taken into account for assessing the performance of lower extremities. However, the contralateral leg injuries and deformation are neglected in the current testing protocol and the pedestrian walking gaits and the e-bike riding scenario have been little consideration. The purpose of this study is to investigate the injury characteristics of the contralateral lower extremities in pedestrian-vehicle and bicyclist-vehicle crashes. Impact simulations were conducted by the Total Human Model for Safety (THUMS) biomechanical dummy, which the testing vehicle struck the pedestrian of the standing and walking postures as well as the bicyclist at the speed of 40 km/h. The femur, fibula, tibia stress, the stretching ratio of ligaments, and the bending angle of the knee joints for the contralateral side legs were measured. Meanwhile, a comparison of the injuries and motions between the two legs was analyzed. The results show that the walking gait increased the injury risk of long bone fracture and ligation rupture, and the e-bike riding posture enlarged the injury risk of long bone fracture and reduced the ligation stretching ratio compared the standing case. Moreover, the stretching ratio of the contralateral LCL was larger than that of the ipsilateral MCL for all scenarios.