The study on which this assessment represents a step in that direction by providing a framework that security planners and policymakers can use to prepare for, and protect against, threats to and vulnerabilities of facility systems. 

The intended audience of this assessment includes security planners, both experts working directly within facility systems and those who are responsible for facility security through their work in governmental or professional organizations, and policymakers. 

Given the open and accessible characteristics of ground transportation systems such as bus and rail, the unpredictability of terrorist attacks, the continual evolution of risk as terrorists learn and improve on their capabilities, and finite resources for security provisions, the industry faces a complex security problem that has existed for decades. This assessment took into account that this facility may have considerable vulnerabilities because of its defined periods of use, designated access points, storage of sensitive personal information, minimal security forces, and numerous avenues of penetration and escape for attackers.