ISO/TS 16951:2021

Overview

ISO/TS 16951:2021 - Road vehicles - Ergonomic aspects of transport information and control systems (TICS) - Procedures for determining priority of on‑board messages presented to drivers - defines formal procedures for prioritizing in‑vehicle messages. It provides two alternative methods (a priority index method and a priority matrix method) to rank messages from TICS and other on‑board systems so that the most important information reaches the driver without compromising safety or increasing workload. The specification applies to traveler information, navigation prompts, traffic advisories, warnings, system status, emergency calling information, toll messages and non‑TICS sources (e.g., phone, telltale alerts), but excludes mandatory or legally required messages.

Key topics and technical requirements

• Two prioritization methods: a mathematically based priority index method (uses evaluator ratings, weighting factors and statistical analysis) and an alternative paired‑comparison priority matrix method (Annex A).
• Data collection process: appoint an examiner, identify and assemble candidate messages, define driving context and scenarios, and select evaluators.
• Evaluation criteria: messages are assessed for criticality (severity if ignored) and urgency (time available for driver action). Weighting factors (k_c and k_u) are used when computing priority indexes.
• Calculation and analysis: procedures for calculating message priority p, computing means and standard deviations across evaluators, selecting weights, verifying data quality and determining priority order.
• Documentation and application: guidance on reporting results, handling additional/new messages, and using priority outputs in message management and HMI behaviour (Annex H - sample report).
• Supportive annexes: system reaction matrix (Annex B), evaluator profiles and recommended evaluator numbers (Annex C), driving scenarios (Annex E), rationale for evaluation criteria (Annex F) and acceptable standard deviations (Annex I).

Applications and who should use it

ISO/TS 16951:2021 is intended for professionals involved with in‑vehicle information and human‑machine interface (HMI) design:

• Vehicle manufacturers and OEM system architects
• TICS suppliers and aftermarket device developers
• HMI / UX and ergonomics engineers assessing driver workload
• Safety engineers integrating warning and alert systems
• Test laboratories and evaluators performing message prioritization studies

Practical applications include integrating message priority into message management systems, designing alert presentation strategies (timing, modality, suppression), and evaluating competing messages to avoid driver distraction while ensuring critical messages are delivered.

Related standards

• ISO 15005 - Dialogue management for in‑vehicle systems (complements message presentation strategy)
• ISO 14813‑1 - Reference for TICS services (describes TICS service categories)

Keywords: ISO/TS 16951:2021, TICS, in‑vehicle messages, message prioritization, priority index, ergonomics, HMI, message management systems.