Since large bus or locomotive accidents are not frequently reported, the cause of bus or train occupant injuries is not clearly defined. For the large public transportation system that is considered much safer than passenger vehicles, most countries have only the roller-over protection safety rule. This paper uses a dynamic sled test approach to understand the effects of impact speed on the risk of cervical injury. The sled impact test simulates lower speed frontal accidents of occupant impact speed in the range 2.9 m/s to 8.0 m/s. From the series of sled test, relative occupant velocity with respect to struck vehicle is considered one of the main factors to investigate the neck injury mechanism. From the results, higher than 7 m/sec of relative occupant impact speed may cause a severe neck injury. It is also found that compressive shear force and extensional neck moment N(sub CE) is the dominated factor for neck injuries. (Author/publisher).
Abstract