2. Crashworthiness evaluation index for carbody structure in railway accidents at level crossings
No index to evaluate crashworthiness is clearly indicated in the design standards for carbody structures in Japan.
On the other hand, although evaluation indices are specified in Western countries, the accident proneness and thedesign specifications for carbody strength and interior facilities such as seat structures are different from Japan.
Therefore, an evaluation index conforming to the actual situations in Japan and having a high correlation with the seriousness of passenger injury has been proposed, by collision analysis performed for accidents at level crossings under various conditions, based on the accident statistics and vehicle specifications in Japan.
How seriously seated passengers would be injured during a collision of a train with a large dump truck (vehicle weight: 11 tons, shipping weight: 0 to 13.75 tons) was estimated by analysis using a train model and a dump truck model (Fig. 1). The accuracy of analysis for these models was verified by collision tests. The analytical parameters set were: train speed, position and angle of collision, and total weight of dump truck; and the analysis objects were the passengers seated on rotary cross seats (cross-seat passengers). The correlation coefficient between the degree of injury estimated under each condition and the integrated value of impact deceleration occurring on the carbody (Fig. 2, referred to the integrated deceleration value) was 0.95 (Fig. 3), which indicated a higher correlation than the maximum value of impact deceleration comform to the American index (correlation coefficient 0.90) and the average value of impact deceleration conform to the European index (correlation coefficient 0.81) (Fig. 4). From the above, the integrated deceleration value was proposed as an evaluation index in Japan.
This will contribute to a reduction of injuries to passengers by applying the proposed evaluation index to the deceleration wave form on the carbody obtained by collision analysis during carbody design.