Potential Scenarios of Concern for High Speed Rail Operations

Currently, multiple operating authorities are proposing the introduction of high-speed rail service in the United States. While high-speed rail service shares a number of basic principles with conventional-speed rail service, the operational requirements on a high-speed rail system are typically more demanding than those for conventional-speed operations. The operating environment will require specialized maintenance and inspection procedures, enhanced protection or grade-separation of highway-rail crossings, effective separation of other rail traffic, and detection of potential hazards along the track to help ensure the safety of the system. With the required implementation of positive train control (PTC) by passenger-carrying rail operators, the frequency and/or severity of several types of railroad accidents can be decreased. While all of these measures will contribute to the overall system safety, incidents that pose a threat to passenger and crew safety may still occur that cannot be prevented through the design of the operating environment alone. It is important to consider these types of incidents when selecting the rail vehicles for use in a particular operation, and include appropriate crashworthiness and occupant protection measures. This paper presents a series of example scenarios of some of the potential hazards that may affect the safe operation of high-speed passenger trains in the United States. These situations are drawn from actual accidents that have occurred in the U.S. and abroad. The scenarios provide a starting point for discussing system safety features, which includes vehicle crashworthiness and occupant protection features. As an operating environment may be designed to limit the likelihood of certain types of incidents from occurring, three different hypothetical high-speed operating environments are discussed in this paper. While the number of potential scenarios varies with each operating environment, in all environments it is important to consider the need for a train’s crashworthiness features to mitigate the consequences of potential incidents.