ISO 17572-4:2020

Overview

ISO 17572-4:2020 - "Intelligent transport systems (ITS) - Location referencing for geographic databases - Part 4: Precise relative location references (precise relative profile)" defines the Precise Relative Location Referencing Method (PRLRM) for exchanging lane- and junction-level location information in geographic databases. The standard specifies a conceptual data model, message content requirements and use cases (including a Japanese implementation example) for encoding and decoding precise relative location references. It does not prescribe a physical file or byte format but does define requirements that any physical format must satisfy.

Key technical topics and requirements

• Conceptual data model: Extends ISO 17572‑1 to include lane-level concepts and lane junctions for precise relative referencing within road networks.
• Location categories: Supports point, linear, area and solid-volume locations at a lane-resolution (e.g., within a lane, between lanes, or within a junction).
• Location referencing methods: Describes methods such as lane number counting and displacement from a reference point for precise relative positioning.
• Message structure and components: Clause 8 specifies the required structure and components of location referencing messages for encoder and decoder systems (logical content, not physical encoding).
• Accuracy and dimensionality: PRLRM must provide sufficient accuracy to distinguish lanes and positions within junctions and must support 3‑dimensional positional information.
• Robustness to coordinate differences: PRLRM shall not rely solely on absolute geographic coordinates (to accommodate differing map representations and tectonic movements).
• Intersection handling: Requires a defined reference point for referencing positions inside intersections; road sections must have a defined direction to disambiguate left/right lanes.
• Conformance and testing: Conformance requires passing the abstract test suite defined in Annex A.

Practical applications

• C-ITS message exchange where lane-level precision is required (e.g., lane‑specific traffic warnings, map updates).
• Automated driving and advanced driver assistance systems (ADAS) that need to reference exact lane positions across different map providers.
• Traffic management centers, road operators and navigation services sharing precise object locations (signs, sensors, obstacles) between heterogeneous systems.
• Encoder/decoder implementations in software or hardware that convert between internal map representations and interoperable location references.

Who should use this standard

• ITS architects and system integrators
• Map and digital geographic database providers
• Automotive OEMs, Tier‑1 suppliers and ADAS developers
• Traffic management agencies and C‑ITS service providers
• Standards implementers and test laboratories

Related standards

• ISO 17572-1:2015 (General requirements and conceptual model)
• ISO 17572-2:2018 (Pre‑coded profile)
• ISO 17572-3:2015 (Dynamic profile)
• ISO 19148:2012 (Linear referencing)

Keywords: ISO 17572-4:2020, PRLRM, Precise Relative Location Referencing, ITS, location referencing for geographic databases, lane-level location, PRLRS, GNSS, C-ITS, automated driving.