Truck and bus frontal impacts account for a major proportion of pedestrian fatalities in many less motorised countries. To understand this phenomenon, the authors have collected injury data on pedestrian impacts with buses and trucks and performed computer simulations to identify critical design parameters at 15-45 km/hr impact velocities for further investigation. A male dummy which was scaled to 50 percentile Indian dimensions has been used for simulations using MADYMO 5.2. Bumper heigh, bumper offset and grille inclination affect the pelvis and thorax forces and head injury criterion (HIC) values critically. Bumper width has less effect. Simulations were performed to optimise for the above-mentioned three parameters. Changes in front geometric parameters reduce injury to the upper body and head below safety limits for the existing force-deflection properties but do not affect leg injuries significantly. Hence, bumpers need to be made less stiff. Injury data show that pedestrians also sustain tibia fractures in bus/truck impacts in apparent low velocity impacts. The computer modelling does not offer adequate explanation for this phenomenon. These simulations confirm that it is theoretically possible to make truck/bus fronts safer for pedestrians in impacts up to 35 km/hr. (A)
Abstract