[OSM-talk] Subway station vs. subway entrance

[Mike Collinson]

At 08:18 PM 18/02/2007, Frederik Ramm wrote:
> >> When mapping the subway network of a major city... should we tag just one
> >> node per subway station, or should we tag every subway entrance[1]??
>
> > I would prefer to have only one icon per station, placed in the middle.
> > This should be sufficient, because when you are near this point one can
> > usually see the entrances.
>
>No. We will someday want to use our data for pedestrian routing -
>automatic generation of instructions like "cross road at intersection
>blah and then enter tube station foo". This is impossible without the
>entrances mapped.


>This calls for the not-yet-implemented "varying level of detail
>dependent on zoom level" feature. Ideally, you want to map the whole
>subterranean area of the subway station with all entrances, plus the
>actual tracks, plus a hypothetical "centre point" that is drawn on the
>low-detail maps where entrances just clutter up things.
>
>I think that for the time being, mapping the centre point (as
>railway=halt name=...) and the entries (perhaps inventing a
>"railway=entrance" coupled with the exact same name used for the
>station?) would be a good compromise. Adding the footways would be a
>plus but there's rendering issues - if you tag them as "tunnels" you
>will get very undesirable results. Most subway stations are really large
>underground "places", and we have the same issue with surface places
>where a number of ways or roads meet in an area where you can move
>around freely - it's not properly mappable currently.


I see Ivan has resolved the base thread topic into a specific proposal here:

http://wiki.openstreetmap.org/index.php/Proposed_features/Subway_entrances

and further comment can be made there.


On the general debate as to whether these "micro-features" should be 
tagged, I suggest that with an eye to the long term:

1) If someone wants to tag something, then tag it.  If in doubt, tag 
it. You may be there only once.

2)  General renderers can choose to ignore the tag totally or only 
show it at certain zoom levels.

3) While they have not appeared yet, I'd predict in 2008 or sooner, 
the OSM buzz will be about specialist renderers for city maps, 
tourist maps, maps for cyclists, specific hobbies/sports ... Then all 
those obscure tags will suddenly become useful.

4) Let's not forget OSM-based navigation software, it is not in the 
spot light now.

5) OSM database-based search querying will also become very 
important.  "Show me the list of all post boxes near me".  These are 
smaller than GPS resolution, but folks still want to know where they are.

Mike
Manila