Experimental and modelling research on coach passengers’ safety in frontal impacts

Abstract

Road traffic accidents involving coaches do not happen very often, but they are very dangerous because they affect a large number of passengers. Coaches (or intercity buses) are not equipped with safety belt harnesses. Valid regulations do not impose any obligation on coach manufacturers to provide intercity buses with either two- or three-point safety belts. This fact may result from the unawareness of risks and injuries that might befall the passengers with no safety belts during accidents. That is the reason why this work aims to compare the aftermath of coach accidents with no safety belts and the ones with safety belts. A detailed aim of this research is to analyse the results of dynamic loads during a frontal impact exerted on coach passengers travelling with and without (two- and three-point) safety belts. This objective was achieved by performing experimental studies and modelling which focused on the process of dynamic load transfer on the human body during a traffic accident. The research was conducted parallel on an adult and a child. The equivalent of a 50th percentile male was a hybrid III dummy (M50), whereas a child at the age of about 10 was represented by a P10 dummy. A numerical model was generated and verified in experimental testing in the scope of kinematics. Also, the comparison of the recorded courses of forces, acceleration, and moments was conducted. The results obtained from the tests were analyzed regarding the injury criteria for head, neck, and thorax. It was observed that both for the two-point safety system and the lack of safety belts, there were high values of acceleration recorded in the centre of gravity of the head. On the basis of the investigations conducted, it was ascertained that only a three-point safety belt system ensures the satisfaction of all injury criteria within admissible standards both in the case of criteria defined in the rules no. 80 and the rules no. 94 determined by the United Nations Economic Commission for Europe. It is the three-point safety belt system which should be obligatory in all intercity buses.