Terrorists have used public transportation as a new area of operations. For those determined to kill large numbers of people, public transportation offers an ideal target. In order to effectively meet the threat posed by terrorism and other forms of violent crime, it is essential that transportation system operators have a thorough understanding of the security measures employed by operators. This volume reports on the first phase of the effort to define which practices are best. The four case studies in this report address transportation measures in Paris, Atlanta, New York, and on the Amtrak rail system. The Paris case study examined the immediate aftermath of the 1995 terrorist bombing in the St. Michel Station. The Atlanta case study focused on the security preparations connected with the 1996 Olympics and the aftermath of the Centennial Park bombing. The Amtrak case study looked at the response to the deliberate derailing of the Sunset Limited in Arizona in November 1995. New York was included because of its size and complexity of its transportation system and the various incidents that have affected it. Each case study examined three issues: policies and practices in effect prior to the incident; the response to the event or heightened threat environment; and recovery efforts. This report also reviewed material complied in the Federal Transportation Agency (FTA) in 1996, which examined existing security practices at nine public transportation systems in the United States, so that it could be more easily compared with the four case studies. In addition, this report also gathered material from public sources by British, Israeli, and Japanese transportation officials. The broader issues that emerged from the study include the following: desirable attributes of security, coordination with authorities, dedicated security personnel, security technology, advance planning, environmental design, communications, training, public involvement, augmented security, restoration services, crisis communication, and inter-city rail versus transit.