Overview
SIST EN ISO 14819-3:2021 (ISO 14819-3:2021) defines location referencing rules for Traffic Message Channel (TMC) systems using the ALERT‑C protocol. Part of the ISO 14819 series for intelligent transport systems (ITS), this standard specifies how to encode and exchange precise location information for traffic and travel information (TTI) messages over mobile bearers (e.g., GSM, DAB) or via exchange protocols such as DATEX II. It supersedes the 2013 edition and formalizes practices widely used in RDS‑TMC (Radio Data System - Traffic Message Channel) implementations.
Key technical topics and requirements
The document focuses on compact, unambiguous location coding suitable for bandwidth‑constrained message channels. Major technical topics include:
- Location coding and location tables: structure, content, hierarchical organization and versioning of TMC location tables.
- Location types and categories: standardized TMC location categories, types and subtypes for roads, junctions and special sites.
- Offsets and directional coding: rules for specifying offsets along links and direction of travel.
- Detailed junction and situation referencing: methods for conventional and complex junctions, detailed link-road coding and situation locations (normal, detailed, precise).
- Identifiers and metadata: country codes, table numbers, WGS‑84 coordinates, language identifiers and name translations.
- Table exchange and interoperability: Location Table Exchange Format, reuse‑of‑location‑codes, roads‑and‑junction‑number‑translation and backward compatibility provisions.
- Constraints and compatibility: constraints for one‑ and two‑way locations, coding of isolated areas, and DLR (detailed local referencing) methods.
The 2021 edition integrates several TISA specifications (e.g., table exchange format, reuse rules) and emphasizes backward compatibility.
Practical applications
This standard enables interoperable, compact transmission of precise location information for:
- RDS‑TMC traffic broadcasts over FM/RDS channels
- Digital radio services (DAB) and mobile bearers (GSM/UMTS/LTE)
- DATEX II‑based exchange between traffic centers, navigation services and third‑party providers
- Route guidance, traffic alerts, congestion and incident reporting in in‑vehicle navigation systems and traffic apps
Who should use this standard
- ITS service providers and traffic information operators
- Navigation system and telematics manufacturers
- Map data and location table publishers
- Radio broadcasters implementing RDS‑TMC channels
- Software developers integrating TMC/ALERT‑C and DATEX II feeds
- National transport authorities and standards bodies
Related standards and keywords
Related documents in the ISO 14819 series and DATEX II specifications support end‑to‑end TTI interoperability. Relevant SEO keywords: RDS‑TMC, ALERT‑C, ISO 14819‑3:2021, location referencing, traffic message coding, location tables, DATEX II, intelligent transport systems, traffic and travel information (TTI).