[Tagging] Feature Proposal - TMC - New tagging scheme for TMC

Tobias Knerr osm at tobias-knerr.de
Thu Mar 29 19:02:03 BST 2012

Graham Jones wrote:
> Err...what does tmc stand for?

TMC stands for Traffic Message Channel, see e.g.

It's a standardized format for transmitting information about blocked
roads, traffic jams, accidents etc. They have IDs for road sections to
be able to describe where one of these events has happened, and mapping
these IDs in OSM would make it possible to use TMC messages in OSM-based
navigation software.

In Germany, we had a huge discussion about TMC a while ago because the
previous tagging scheme for TMC IDs was pretty horrible - see this node
for example:

So I'm happy that there is now a much more sensible proposal available.

Heinrich Knauf wrote:
>> http://wiki.openstreetmap.org/wiki/DE:Proposed_features/New_TMC_scheme

This is clearly a massive improvement. The long and detailed description
makes it look a bit more complicated than it really is, but considering
that it also gives some background about how TMC works and explains why
the proposal makes these exact suggestions, the length of the text seems

Apart from the obvious improvements (shorter keys, country codes instead
of numbers etc.), I especially appreciate that it should be relatively
hard to break even if you don't know much about it. You can still split
a way with tmc=... tag or move some of its nodes without causing any
harm. And if you do break something nevertheless, it will probably be
easy to spot most of the time.

So, I think this proposal is as mapper-friendly as possible, considering
the complex subject matter.

Btw, have you considered to create some rendering of these TMC tags to
make them more visually accessible?


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