[Tagging] Carriageway divider

Fabrizio Carrai fabrizio.carrai at gmail.com
Sun Sep 2 21:23:21 BST 2012


2012/8/26 Martin Koppenhoefer <dieterdreist at gmail.com>

> [...]
>
> > The
> > divider tag has been proposed, but I think it has been demonstrated
> > not to work, as routing decision are made on the node and not on the
> > line.
>
>
> I can't remember that there was a demonstration that this approach
> doesn't work. Routing engines usually get data that is postprocessed,
> so the important thing is that the correct information is contained in
> the data and can be derived. My guess is that nobody has seriously
> tried to evaluate the divider tag for routing so far.
>
> cheers,
> Martin


Indeed the assertion that the router decide on the node (it has been
addressed more than once...) let me thought on the real usefulness of the
divider tag, at least to help the problem I identified.

Anyhow I think that Martin is right: the data have to be processed, also to
load the relations for the turn restriction that involve "from-via-to"
nodes and highways.

To avoid a turn crossing the "continuos line", the divider attribute should
have to be checked on

- the current highway
- the following highway on the driving direction

If so a left turn should have to avoided. Simple algorithm, but it looks
like out od normal routing schemes, and I don't know if a router could do
that (or it could be worth to do that).

Ciao
Fab,
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