On 12.01.2011 17:27, Richard Mann wrote:
On Wed, Jan 12, 2011 at 4:07 PM, ant<[email protected]> wrote:
So the point of stop area relations is to prepare the data to be interpreted as
a network and thus to make routing... easy.
Stop areas are about linking the stop (notionally on the footway) to
the road. Or they are about linking platforms with the same name. You
can do that as you go along. The stopping_position and stop_area
relation are just clutter.
If you know the latlons of two stop areas, you can work out how to get
between them by running your pedestrian routing algorithm. Marking
footways between stops (other than the ones you can assume are
adjacent to any roads not marked with footway=no) is more useful than
linking the stop areas into a group and implying there is free access
between any stop area within it.
Basically you use relations to link objects which have a geographical
relationship - not just a geographical proximity.
I think there is some misunderstanding. I'm talking about the use of
relations to group stop positions and platforms together that are
considered a stop or station where one can change vehicles. These could,
for example, consist of two separate tram stops and four different bus
stops and could serve several bus and tram lines (or even metro). Maybe
this should be tagged "stop_area_group" rather than "stop_area". In any
case these objects certainly have a relationship - they serve as
interchange nodes in a public transport network.
I'm not defending the use of stop area relations on singular stops that
have only one platform on each side of the road... that would be clutter
indeed.
There's sense in adding "group" objects if data relates to the group
(eg to a station and not to it's individual platforms), but I'd find a
convenient node or area to hold the info, not put it on an unnecessary
relation. And if the information is relatively simple (eg a name), I'd
settle for putting it on all the nodes, rather than create an
artificial single object to hold it.
As I said, it depends on the scale of the stop (area (group)).
cheers
ant
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