Evaluating the Severity of Safety Envelope Violations in the Proposed Operational Safety Assessment (OSA) Methodology for Automated Vehicles

As the automated vehicle (AV) industry continues to progress, it is important to establish the level of operational safety of these vehicles prior to and throughout their deployment on public roads. The Institute of Automated Mobility (IAM) has previously proposed a set of operational safety assessment (OSA) metrics which can be used to quantify the operational safety of vehicles. The OSA metrics provide a starting point to consistently quantify performance, but a framework to interpret the metrics measurements is needed to objectively quantify the overall operational safety for a vehicle in a given scenario. This work aims to present an approach to applying a calculation of the safety envelope component of the OSA metrics to rear-world collisions for use in such an assessment.

In this paper, the OSA methodology concept is introduced as a means for quantifying the operational safety of a vehicle. Historical collision data from government databases are then used to define car-following conflict scenarios in the Human, Vehicle, Environment (HVE) simulation software package in order to extract kinematic data of the collision scenario participants. These kinematic data are used to calculate the Minimum Safety Envelope (MSE) OSA metric and identify MSE violations for the simulated collision scenarios. The Minimum Required Deceleration (MRD) is also introduced as a rearrangement of the MSE formulation to assess the outcome of a scenario with regards to the braking capability of the following vehicle. The results of these calculations are then compared across a variety of scenarios to evaluate the relationship between the severity of a safety envelope violation in the context of the scenario. This paper presents a fundamental step towards establishing an objective OSA methodology for AVs.