Overview
ISO/TR 21974-1:2018 - Naturalistic driving studies - Vocabulary - Part 1: Safety critical events defines a common vocabulary for annotating video and related data from Naturalistic Driving Studies (NDSs) collected in real-world, uncontrolled driving. Its primary aim is to standardize terms used when coding safety‑critical events (SCEs) so that datasets, annotation protocols, and analytic results are replicable and comparable across research projects (e.g., SHRP 2 and follow‑on studies).
Key topics and technical scope
- Core definitions: clear terminology for SCEs, conflicts, conflict partners, subject vehicle, crash, road departure, evasive manoeuvre, proximity conflict, trajectory conflict, single‑vehicle conflict, metadata, trigger, and urgent response.
- Conflict taxonomy: three general conflict classes - trajectory, single‑vehicle, and proximity - used to categorize SCEs observed in NDS video.
- Annotation focus: vocabulary intended for manual review and coding of video and basic kinematic signals (vehicle speed, longitudinal/lateral acceleration); supports consistent annotation of event characteristics rather than prescribing detection algorithms.
- Annex material: informative annexes providing a conceptual framework for categorizing SCEs (Annex A), principles of conflict classification (Annex B), and additional conflict attributes (Annex C).
- Instrumentation recommendations (informative): preferred camera views (forward, in‑vehicle driver view, optional rear/side views) and a minimal set of kinematic measures typically available from the instrumented (subject) vehicle.
- Scope limits: the document defines vocabulary only - it does not mandate methods for event detection, complete annotation schemas for all behaviours (e.g., distraction), nor procedures for selecting baseline/control samples.
Practical applications and users
- Researchers and data coders: ensures consistent video annotation and event characterization across NDS datasets to improve reproducibility and reduce coder ambiguity.
- Naturalistic study designers: informs instrumentation choices and metadata capture to support standardized annotations.
- Vehicle OEMs and safety analysts: facilitates comparison of safety events and behaviour across fleets or study populations.
- Regulators and traffic safety professionals: supports harmonized reporting and interpretation of NDS-derived SCEs for policy and countermeasure evaluation.
- Data archive managers: enhances interoperability of shared NDS datasets (e.g., SHRP 2) by supplying a common annotation vocabulary.
Related standards
- Part of the ISO 21974 series (see ISO website for other parts).
- References vehicle classification concepts cited in regulatory material (e.g., Council Directive 70/156/EEC) where relevant to vehicle categories M and N.
Keywords: ISO/TR 21974-1:2018, naturalistic driving studies, safety-critical events, NDS, video annotation, conflict taxonomy, SCE, subject vehicle, trigger, traffic conflict.