The Railway Technical Research Institute (RTRI) has obtained basic data to develop an impact absorption structure and safer internal fittings for vehicles to reduce passenger injury. This was done by conducting a simulation analysis of passenger behaviors in response to an impact caused by accident or disaster (Fig. 1).
Firstly, the relationship between impact acceleration and Head Injury Criterion (HIC: index of potential head injury) was clarified (Fig. 2) at passenger car floor level for passengers without support such as straps. This data can be reflected in the design of vehicles' impact absorption structure to avoid severe injury in collisions.
A simulation analysis was then performed of typical passenger injury patterns in a commuter train accident. Where a passenger standing in front of a long seat is injured by head impact with the floor, the degree of injury depends on the relative position of other passengers. The simulation showed that HIC is lowest when two passengers are standing laterally in line with no step in the direction of the train width, and also demonstrated that the arrangement of straps in a row along the long seat is currently optimized (Fig. 3).
Passengers sitting beside the tubular handrail on a long seat may be injured by chest impact with the side pipe. To combat this, a system was proposed in which the fixed handrail is released on impact if the torque around the handrail fixture point due to the collision exceeds a certain limit (fixed/released torque). An investigation of thorax injury criterion for a given impact condition with varied fixed/released torque showed a reduction in injury when the fixed handrail is released (Fig. 4).