Occupant safety and injuries in coach frontal collision: a literature review

Frontal collisions of coaches contribute to more than half of the total number of casualties in traffic accidents, making it important to study frontal collisions of coaches. This literature review covers regulations, injury criteria, and factors influencing occupant injury, primarily referenced national standards on seat stability, and occupant safety. Existing regulations such as these are important because they highlight the injury criteria for the head, neck, chest and lower limbs of occupants. Injury criteria outside of the existing regulations are also highlighted, particularly the need to include both linear and angular accelerations of the head. In addition, numerous factors within the interior structure of a coach can impact injury severities. The use of different restraint systems and alterations in seat parameters can have varying effects on different limbs of the occupant during accidents. The researches show that three-point seat belts are advantageous and can protect occupants’ heads and necks, both adults and children. At the same time, proper seat spacing, seat inclination and other seat-related parameters also influence the injuries to the occupant’s head and neck. For example, occupant head injury risk is high when the seat inclination is between 105° and 115°, and occupant neck risk is high when the seat inclination is 95°. Future studies should evaluate the less-covered areas of occupant safety such as the safety of driver and co-driver. This review highlighted the critical need to update and enhance regulatory requirements based on current research findings to reduce the risk of occupant injury.