The guide can be used by transit system planners, security personnel, and managers in developing plans, procedures, and capital programs, and transit systems are encouraged to take a proactive, prevention-oriented systems approach to security. The guide notes that the concept of transit system security involves a planned, disciplined, systematically organized, before-the-fact process of identifying, assessing, and minimizing potential security threats and areas of vulnerability. Two sections comprise the guide: (1) security incidents and issues; and (2) security problems--general security issues, crimes against passengers, crimes against the transit system, and crimes against the public (critical incidents and terrorist acts). A systems approach to transit system security and components of the security planning process are described. Endnotes, tables, and figures