Terrorists see transit and passenger rail as an attractive target. Designed for public convenience, trains and stations offer terrorists easy access to crowds of people in confined environments where there are minimal security risks and attacks can cause high casualties. This report examines the unique attributes of the terrorist threat, how security measures against terrorism have evolved over the years, and their overall effectiveness. Does security work? Empirical evidence is hard to come by. Terrorist incidents are statistically rare and random, making it difficult to discern effects. The fact that terrorists focus most of their attacks on targets with little or no security suggests that security influences their choice of targets. Increased security does not reduce terrorism overall, but appears to push terrorists toward softer targets. These indirect effects are visible only over long periods of time.
Public surface transportation poses unique challenges. It is not easy to increase security without causing inconvenience, unreasonably slowing travel times, adding significant costs, and creating vulnerable queues of people waiting to pass through security checkpoints. This has compelled rail operators to explore other options: enlisting passengers and staff in alerting authorities to suspicious objects or behavior, random passenger screening, designing new stations to facilitate surveillance and reduce potential casualties from explosions or fire, and ensuring rapid intervention.