Passenger rail systems are vital components of the nation's transportation infrastructure, encompassing rail transit and intercity rail. In the U.S., passenger rail systems provide approximately 14 million passenger trips each weekday, and commuters rely on these systems to provide efficient, reliable, and safe transportation. Terrorist attacks on passenger rail systems around the world, such as the March 2010 Moscow, Russia subway bombings and the July 2006 passenger train bombing in Mumbai, India, highlight the vulnerability of these systems. This book examines the latest technologies being implemented in passenger rail security and safety efforts including explosives detection and advanced imaging technologies.