Vehicle performance metrics analyze data sets consisting of subject vehicle's interactions with other road users in a nominal driving environment and provide certain performance measures as outputs. To the best of the authors' knowledge, the vehicle safety performance metrics research dates back to at least 1967. To date, there still does not exist a community-wide accepted metric or a set of metrics for vehicle safety performance assessment and justification. This issue gets further amplified with the evolving interest in Advanced Driver Assistance Systems and Automated Driving Systems. In this paper, the authors seek to perform a unified study that facilitates an improved community-wide understanding of vehicle performance metrics using the lead-vehicle interaction operational design domain as a common means of performance comparison. In particular, the authors study the diversity (including constructive formulation discrepancies and empirical performance differences) among 33 base metrics with up to 51 metric variants (with different choices of hyper-parameters) in the existing literature, published between 1967 and 2022. Two data sets are adopted for the empirical performance diversity analysis, including vehicle trajectories from normal highway driving environment and relatively high-risk incidents with collisions and near-miss cases. The analysis further implies that (i) the conceptual acceptance of a safety metric proposal can be problematic if the assumptions, conditions, and types of outcome assurance are not justified properly, and (ii) the empirical performance justification of an acceptable metric can also be problematic as a dominant consensus is not observed among metrics empirically.

翻译：车辆性能指标通过分析主体车辆在标称驾驶环境中与其他道路使用者交互的数据集，输出特定性能度量值。据作者所知，车辆安全性能指标研究可追溯至至少1967年。然而时至今日，学界仍未形成被广泛接受的单一安全性能评估指标或指标体系。随着先进驾驶辅助系统与自动驾驶系统研究兴趣的持续升温，这一问题愈发凸显。本文旨在开展统一性研究，以引导车辆交互运行设计域作为性能比较的通用基准，促进学界对车辆性能指标的深入理解。具体而言，作者系统分析了1967至2022年间文献中33项基础指标及其最多51种变体（采用不同超参数配置）的多样性特征，包括构造性公式差异与实证性能差异。实证性能多样性分析采用两类数据集：包含正常高速公路驾驶环境下的车辆轨迹数据，以及涵盖碰撞事故与近碰撞事件的高风险案例。进一步分析表明：（i）若未对假设条件、边界条件及结果保障类型进行合理论证，安全指标方案的概念接受度可能存在问题；（ii）由于指标间未形成显著的实证共识，可接受指标的实证性能论证同样可能存在缺陷。