Simulation Study of Passenger Reaction to Train Collision
We are now studying how to minimize the damage to passengers when trains collide. For this purpose, the first thing to be made clear is how the interior equipment or passengers suffer from the collision; to be more specific, where and how they are hit or bumped. Then we consider simulating a series of passenger movements before direct impact comes, leading to a possible injury.
Several injury patterns emerge from our surveys of the past records of train collision accidents. One pattern identified is the case of a passenger sitting on the long seat being hit in the breast. Figure 1 shows its simulation in which three models occupying a long seat are subjected to an accelerating impact. In this case it is assumed that the collision did not lead to a derailment of vehicles and accordingly it is supposed that the human body is exposed to a shock acting in the direction of train progress. Thereby among the three passengers, the one sitting close to the railing must be inflicted with the greatest impact.
Another pattern is conceivable in which a standing passenger is wounded by a heavy blow to the head. Figure 2 is a simulation of this case assuming about the same intensity of impact acceleration as in Fig.1. The situation is such that the three bodies sit on the long seat across the running direction, resulting in a simple domino effect caused by the collision. When viewed in terms of HIC (Head Injury Criteria) popularly applied to an auto accident, this may be considered a non-fatal case.
Thus it can be said that given the accident situation and the internal structure of vehicle, a simulation analysis is feasible. As a matter of fact, however, before the simulation can be practically valid enough, a lot of problems stand in the way. Standing posture in the present case is just one of the problems. To solve this we undertake an experiment
using a real human to investigate the falling characteristic of a human exposed to an impact acceleration (Fig.3). When the linear accelerator with a human aboard is abruptly started, the acceleration generated causes the human to fall down.
At first this movement is analyzed. Next, the movement of a human body model subjected to a similar impact acceleration is investigated using the same software as above. The current stage of our study is a comparison of the two outcomes and determination of the validity of simulation based on the difference between them.
It should be noted that the present work is being subsidized by the MOT of the Japanese Government as part of a research program "Technical Development Related to Passenger Safety in Traffic Accident".
Fig.1 Simulation of three passengers receiving an impact sitting on a long seat
Fig.2 Simulation of three passengers receiving an impact in a standing posture
Fig.3 A scene of an experiment investigating the human falling characteristic