Tactical Safety Reasoning - A Case for Autonomous Vehicles

Self driving cars have recently attracted academia and industry interest. As planning algorithms become responsible for critical decisions, many questions concerning traffic safety arise. An increased automation level demands proportional impact on safety requirements, currently governed by the ISO 26262 standard. However, ISO 26262 sees safety as a functional property of a system and fails to cover emergent concerns related to autonomous decisions. In order to fill this gap we propose the field of tactical safety, which extends safety analysis to planning and execution of driving maneuvers, response to traffic events or autonomous system failures. It is meant to complement, not to replace functional safety properties of a system and allows the analysis of autonomous agents from a safe behavior point of view. We draw the requirements for tactical safety from an automotive standard which defines functional elements for advanced driving automation systems.