Dynamic loads exerted on legs of seated passengers during frontal collision of a bus with an obstacle

The dynamic loads exerted on legs of seated bus passengers during a frontal traffic collision were studied. Passengers are being displaced as a result o f a bus collision with an obstacle and the nature of such displacement depends on the design of seats and personal protections applied (2- or 3-point safety belt or no belt). The study describes the dynamic loading of thighs as afunction of time and the relationship between the operation of personal protections and leg injuries. Most injuries result from hitting components of seats faced by passengers. The results were recorded using sensors placed in the dummies' thighs and filmed with a Photosonics camera. The video was used for studying the kinematics of the dummies' legs of the dummy secured with a 3-point belt, secured with a 2-point belt and unsecured, including possible combination of extreme forces with a specific type of leg displacement. Knee movement trajectories and consequences of dummy hips rotation on the bus seat were also presented. Problem of rotation of the hips of the dummy secured with a 3-point belt has also direct influence onto the dynamic loads affecting legs. The research demonstrates the existing design of 3-point safety belts is unsuitable for protection of seated passengers and the clearances between seat rows are insufficient. The need for applying new energy-absorbing materials or modification of seat design is obvious.