TMC stands for Traffic Message Channel. Its purpose is to deliver information about traffic distortions or warnings to mobile receivers such as navigation devices. The information is contained in messages, which are broadcast together with radio broadcasts over FM radio. A specific radio receiver is needed to pick up this inaudible signal. Every message contains information about an event, such as a traffic jam, and the location of that event. Both are encoded as numbers referring to lookup tables - the event code list and location code list. The location code lists are issued by every country that in which TMC is provided, in some countries they are freely available. See the Wikipedia article about TMC for more information.
TMC data types
The TMC location code lists of the countries are the most interesting information for OpenStreetMap. They connect the location information from the TMC messages to geographical features. In particular, they contain all major streets, intersections and usually lots of usefully POIs (fuel-stations, border-crossings, ...).
The German location code list has been imported into OSM, see TMC/TMC_Import_Germany.
The TMC event code lists are more interesting for developers of routing software. They connect the event codes used in TMC messages to a description of the events at the specified location. Each event has an English description. Official translations of these descriptions are issued by the countries where TMC is available.
There exist different tagging schemes for TMC data. Only the newest one is recommended for mapping new TMC data.
Proposed and currently recommended tagging scheme
The tagging scheme which is currently recommended for tagging TMC locations has been developed in long discussions in this forum thread. It uses a number of relations which are tagged in the form type=tmc:*, see the following pages for details:
The development of this tagging scheme is described in the following proposals:
An older proposal which is not currently in use can be found here: New TMC scheme.
Old TMC data
See TMC/TMC_Import_Germany#Tagging_Schema for the old tagging of imported TMC data in Germany, which is still in use and should remain in the database until its users have switched to the new tagging.
Mapping import helper and TMC location viewer
For a semi-automated import and quality check the TMC viewer and import helper can be used. It contains all TMC locations for the countries listed below. There is no need for mappers to obtain the location code lists themselves. The following purposes are served by the TMC viewer:
- Display all TMC locations on a map.
- Display the TMC data mapped in OSM in the new and recommended tagging scheme.
- Import locations which are not already mapped into JOSM or Merkaartor via remote control.
- Help finding the correct OSM objects to map by their old-style TMC tags.
- Completeness and correctness check for type=tmc:point and type=tmc:link relations.
So far we have information about the following datasets:
|Belgium||Obtained for import, imported in mapping tool|
|Czech Republic||Not yet requested||Location tables are available at a fee of € 500. --Stanton (talk) 11:33, 25 May 2015 (UTC)|
|Denmark||Not yet requested||Can be downloaded for free, but license is only for incorporation in navigation products in such a way that the tables cannot easily be separated from the product; any other use (likely also use in OSM) requires an individual agreement. --Stanton (talk) 00:13, 8 April 2017 (UTC)|
|Finland||Obtained for import, imported in mapping tool|
|France||Obtained for import, imported in mapping tool|
|Germany||Obtained for import, imported in mapping tool||Import to OSM allowed, see DE:Kommunikation. --Lulu-Ann 14:52, 1 December 2009 (UTC)|
|Italy||Obtained for import, imported in mapping tool|
|Netherlands||Not yet requested||Can be requested via email to firstname.lastname@example.org|
|Norway||Obtained for import, imported in mapping tool|
|Slovakia||Not yet requested|
|Spain||Obtained for import, imported in mapping tool||Link down|
|Sweden||Obtained for import, imported in mapping tool|
|Switzerland||Not yet requested||Can be requested via email to email@example.com|