Overview
ISO 14819-3:2021 - Intelligent transport systems - Traffic and travel information messages via traffic message coding - Part 3: Location referencing for Radio Data System‑Traffic Message Channel (RDS‑TMC) using ALERT‑C - defines the rules for specifying geographic locations in compact, digitally coded Traffic and Travel Information (TTI) messages. The standard is focused on RDS‑TMC (Radio Data System - Traffic Message Channel) using the ALERT‑C protocol and covers how location references are encoded, maintained and exchanged in pre‑defined location tables used by TMC services.
Key topics and technical requirements
- Location tables and coding: Structure, semantics and content of TMC location tables used as the authoritative source for location codes (location IDs) referenced in RDS‑TMC messages.
- Versioning and exchange: Rules for table versions, version control and exchange formats (including integrated TISA Location Table Exchange practices).
- Location types and categories: Classification of locations (road links, junctions, points of interest, urban areas) and subtypes to support concise TMC messages.
- Offsets and directionality: Encoding of offsets along road links and specification of road direction for one‑ and two‑way locations.
- Detailed junction and situation referencing: Methods for conventional and complex junctions, detailed link coding and precise location referencing (DLR methods).
- Geodetic and metadata: Use of WGS‑84 coordinates, country codes, language/script identifiers and name translations to support multilingual receivers and cross‑border services.
- Constraints and backward compatibility: Rules ensuring compact ALERT‑C message compatibility, reuse‑of‑location‑codes, isolated area handling and backward compatibility with earlier table versions.
- Validation and governance: Roles for Traffic Information Centres (TICs), service providers and bodies such as the Traveller Information Services Association (TISA) in ID allocation and table validation.
Practical applications and users
ISO 14819-3:2021 is intended for organisations that create, transmit or consume compact traffic messages:
- Traffic Information Centres (TICs) and data providers creating TTI messages for broadcast and exchange.
- Broadcast operators (FM/RDS, DAB) and mobile bearer service designers implementing RDS‑TMC services.
- Navigation and telematics manufacturers (in‑vehicle systems, smartphone apps) decoding ALERT‑C TMC messages.
- Transport authorities and fleet operators integrating TMC feeds into traffic management and routing systems.
- Data integrators exchanging TTI via protocols like DATEX II who need compact location referencing.
Practical benefits include interoperable, bandwidth‑efficient delivery of traffic alerts, standardized location maintenance across borders, and predictable receiver behaviour for traveler information services.
Related standards
- ISO 14819‑1 - ALERT‑C coding protocol for RDS‑TMC (message protocol).
- ISO 639‑1, ISO 15924 - language and script codes referenced for name translations.
- TISA specifications (Location Table Exchange Format, validation rules) are integrated or complementary to this part.
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