[talk-au] Mapping interchanges levels or turn restrictions

[Franc Carter]

On Tue, Jan 12, 2010 at 3:57 PM,  <cam_daw at fastmail.fm> wrote:
> On Mon, 2010-01-11 at 21:44 +1100, Roy Rankin wrote:
> With the resolution and newness of Nearmap images Freeway/Motorway
>> interchanges are being mapped in detail rather than schematically. This
>> brings up the issue on how to best do this.
>>
>> ...
>>
>> (http://www.openstreetmap.org/?lat=-33.82907&lon=151.21494&zoom=17&layers=0B00FTF
>> ) The mapper did not realise that ways with turn restrictions must break
>> at the via node. Unfortunately the current tested JOSM does not handle
>> turn restriction relations properly when a way is split and much effort
>> is required to fix up the relations after a way split. As each way had
>> quite a few turn restrictions I realized that after splitting the ways
>> it would require some time to sort out the relations. I thus used method
>> 2 above and deleted all the relations.
>>
>> Regards,
>> Roy Rankin
>>
>
> Good point there Roy,
>
> This intersection was my doing, I wasn't 100% sure how to do turn
> restriction relations that well, and OSM's documentation for straight_on
> isn't clear.
> http://wiki.openstreetmap.org/wiki/Relation:restriction
>
> That is a particularly messy intersection to deal with:
> http://www.openstreetmap.org/?lat=-33.829754&lon=151.214575&zoom=18&layers=B000FTF
>
> Personally I'd prefer to use turn restriction relations rather than just
> using different layer tags for these complex intersections, as it seems
> to be more the "proper way" of doing it.
>
> After having a look at your handywork fixing up that intersection Roy,
> it does indeed make reading the intersection much easier in JOSM.
>
> But indeed as you say, just using layers, one way roads, and some
> non-connecting ways is in itself a rather elegant way of doing things.
>
> Would anyone else like to comment?

I'm very much in favour of the turn restrictions over the layering. It
is physically possible to make all these weird turns, it's just not
legal to do so. Therefore I would prefer to map it this.

cheers

>
> Regards,
> Rhubarb.
> --
>
>  cam_daw at fastmail.fm
>
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-- 
Franc