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

Robert Stack traffictower at gmail.com
Tue Apr 17 23:55:25 BST 2012


Hello all,

A very interesting proposal, thanks.  The TMC Inspector you (Infoware)
provided (http://osm-tmc.infoware.de/tmc/) is most helpful in reviewing
this, too.  Here's an additional question beyond those from Eckhart Worner
and others.  Some ways span well beyond a single adjacent pair of TMC
locations.  For example, see way 4413896 (on Autobahn A20 near Rostock;
vicinity of coordinates 54.02593, 12.23133).  There are several TMC
locations along this way (10572, 47239, 10573, and a few more at the
boundaries)..

Will such long ways that span two or more location codes need to be rebuilt
into separate ways to make this work?  Or, alternatively, could the tagging
be expanded to have multiple TMC tags for a way, each one specifying which
portion of a way it applies to?  I realize that this would increase the
complexity of the tagging which would diminish the simplicity appeal of the
proposed tagging scheme.

thanks,

..robert
Robert Stack
traffictower at gmail.com

--

Hi,

Am Mittwoch, 11. April 2012, 15:42:29 schrieb fly:
>* I still do not get one major point which was totally left out on the first*>* scheme. What actually belongs to a "point" and how are they tagged. *Especially
>* on big crossings and roundabouts I always was confused (e.g. it might be*>* possible that a part of this point is blocked but how do I know which one *and
>* you might be able to use  the first/last exit/entrance of a junction but not *the
>* rest. )*
Indeed, this is what I was worried about as well.
Here's a proposed (partial) fix, which starts from the original proposal.

Let's assume that 123, 456 and 789 are connected LCD which describe a road.
Further assume that at 456 there's a big intersection.
Then:
- All ways between 123 and 456 are marked tmc=DE:123+456, and all ways between
456 and 789 are marked tmc=DE:456+789.
- All ways on the intersection 456 leading from 123 to 789 are then marked
tmc=DE:456+.

This has several advantages:
- A traffic jam between 123 and 456 will not block the intersection 456 anymore.
- Exits are defined as follows:  an exit at 456 in positive direction starts at
a way that is tagged either tmc=DE:456+ or tmc=DE:123+456 ("from"), uses a
node that is part of a way tagged either tmc=DE:456+ or tmc=DE:456+789 ("via")
and ends at a way that is tagged neither tmc=DE:456+ nor tmc=DE:456+789, nor
tmc=DE:123+456 ("to"). An exit is therefore a maneuver. This may sound a bit
technical at first, but none of this is exposed to the tagging, and the idea of
an exit is probably quite intuitive.
- Likewise, entries are defined.
- Automatic consistency checking is still possible, as there are no holes.

There is at least one issue that still has to be addressed: this tagging does
not imply an ordering of the exits / entries; it is not clear what the first,
second… exit would be.

Eckhart Wörner
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