ISO 21717:2018

Overview

ISO 21717:2018 - "Intelligent transport systems - Partially Automated In‑Lane Driving Systems (PADS) - Performance requirements and test procedures" - defines system‑level requirements and test methods for vehicle features that provide partial longitudinal and lateral automation while keeping the vehicle in its current lane. The standard applies to passenger cars, commercial vehicles and buses and is explicitly not for automated driving systems of SAE level 3 or higher (see SAE J3016:2016).

Core intent: standardize basic control strategy, minimum functionality, driver interface elements, diagnostics and failure reactions, and performance test procedures for PADS.

Key topics and technical requirements

• Basic control strategy: PADS must control speed (including adaptive following) and lane‑keeping without performing lane changes. The system relies on vehicle‑to‑vehicle and onboard sensing of:
  • distance to forward vehicles,
  • motion of the subject vehicle,
  • vehicle position within the lane,
  • driver commands.
• System states: defined states and transitions include off, stand‑by, active, longit (longitudinal control only) and longit‑lat (combined longitudinal and lateral control). Driver override capability is mandatory.
• Longitudinal control linkage: requirements reference ISO 15622 (Adaptive Cruise Control). For PADS:
  • If Vmin < 5 m/s → ACC type FSRA per ISO 15622 required.
  • If Vmin ≥ 5 m/s → ACC type FSRA or LSRA2 per ISO 15622 required.
  • OEM selects operational speed range; difference between Vmin and Vmax must be at least 8 m/s.
• Driver interface & monitoring: minimum display, operation elements and driver monitoring to ensure driver responsibility for safe operation.
• Diagnostics & failure reactions: minimum requirements for detecting failures, informing driver and safe fallback strategies.
• Performance test procedures: environmental, test‑course and vehicle conditions, test installation/configuration and step‑by‑step procedures (including example curved test tracks).

Note: ISO 21717 does not specify sensor performance or cooperative communication link details.

Applications - who uses ISO 21717

• OEMs designing PADS functions for cars, buses and commercial vehicles.
• Tier‑1 suppliers developing lane‑keeping and adaptive longitudinal control modules.
• Test labs and certification bodies implementing objective performance evaluation and compliance testing.
• Regulators and policymakers referencing harmonized requirements for partially automated in‑lane driving features.
• System integrators and validation engineers creating test plans for environmental and track conditions.

Related standards

• ISO 15622 - Adaptive cruise control (ACC) performance and test procedures (referenced for longitudinal control).
• SAE J3016:2016 - Taxonomy and definitions of driving automation levels (used to clarify applicability).
• Other sensor/communication standards may be used to extend PADS at subsystem level.

Keywords: ISO 21717, PADS standard, Partially Automated In‑Lane Driving Systems, performance requirements, test procedures, intelligent transport systems, lane keeping, adaptive cruise control, driver monitoring.