The Federal Railroad Administration has conducted a number of detailed investigations of passenger train accidents which result in fatal injuries and/or multiple serious injuries. The objective of these investigations is to reconstruct the sequence of events and to determine the causal mechanisms for injuries and fatalities.
This paper presents a reconstruction of the sequence of events and the train collision dynamics results for three accidents:
- the passenger train to freight train collision with a closing speed of 80 mph in Chatsworth, California on September 12, 2008;
- the passenger train to freight train collision with a closing speed of 33 mph in Chicago, Illinois on November 30, 2007;
- the passenger train to freight car collision with a closing speed of 23 mph in Canton, Massachusetts on March 25, 2008.
The reconstructions are developed from information gathered during field investigations of occupant injury (via interview and reports), damage to the interior fixtures, structural damage to the equipment, and wayside damage. Engineering analyses are then conducted to integrate the data gathered during the field investigation, including train collision dynamics modeling which estimates the gross motions of each of the rail cars during the collision.
To assure that the model reasonably captures the collision dynamics, model results are first compared with the post-accident equipment damage information gathered in the investigations. The model is then used to estimate the severity of the decelerations experienced by the occupants. The Secondary Impact Velocity (SIV) provides an indication of severity of the interior environment experienced by the passengers and crew during the accident. In a companion paper, the SIVs are correlated with the observed level of damage to the interior seats and fixtures.
The selected accidents represent a range of collision conditions, with closing speeds from 23 to 80 mph, single- and multi-level passenger cars, and colliding freight equipment from a long train to a single car. The selected accidents are similar in that in all cases the passenger trains are locomotive-led. The differences in collision speed and mass of the colliding equipment resulted in substantial differences in the observed damage to the equipment as well as differences in the estimated SIVs. These differences are discussed in the paper.