This report is the fourth of four volumes concerned with developing safety guidelines and specifications for high-speed guided ground
transportation (HSGGT) collision avoidance and accident survivability. The overall approach taken in this study is to first formulate collision
scenarios to which an HSGGT system may be exposed. Then existing U.S. and foreign rules, regulations, standards, and practices concerned with either preventing the occurrence of a collision, or mitigating the consequences of a collision are reviewed, together with pertinent practices from other forms of transportation, leading to the formulation of guidelines and specifications for collision avoidance and accident survivability.
This volume provides a detailed specification for HSGGT system collision avoidance and accident survivability. The specification is structured in three levels. The first level specifies an overall system safety performance requirement in terms of accident and casualty rates that must not be exceeded. The second level provides separate minimum requirements for collision avoidance and accident survivability in terms of severities of consequences or frequencies of occurrence that must not be exceeded. The third level provides minimum requirements for safety critical subsystems such as vehicle brakes and signal and train control systems. Supporting sections of the report describe the considerations leading to the development of the specification, and methods of performing risk analyses called for in the specification.