[Talk-transit] Summary of Public Transport Proposal Criticism -> a real example from Zürich

Michael von Glasow michael at vonglasow.com
Sun Feb 6 23:23:35 GMT 2011

On 02/05/2011 06:09 PM, Richard Mann wrote:
> On Sat, Feb 5, 2011 at 12:32 AM, Michael von Glasow
> <michael at vonglasow.com>  wrote:
>> if I may just comment on the relation: I would also use "stop"
>> rather than "forward_stop" and "backward_stop" for the roles since the
>> outward and return directions of a spoon route are somewhat hard to tell
>> apart. (Unless one stop in the loop is formally designated as the terminus
>> where services routinely end.)
> You have to use forward_stop and backward_stop if you combine the two
> directions in one relation, otherwise the same-named stop in the two
> directions don't get combined on the line diagram.
You're probably right (though I haven't tried plotting spoon lines yet), 
when the same stop is served twice, the tool needs that information. 
"stop" works well for single-direction relations. Maybe it would be best 
to use "forward_stop" and "backward_stop" for the stops which are served 
in both directions and "stop" for the stops in the loop.

Then again, I'm wondering whether that's too much tagging for the 
renderer already. Couldn't a well-written renderer look at the stop 
names and deduct from these the fact that the stop is the same? Or can 
you think of any case in which that wouldn't work?
> I think if you use
> two relations, one for each direction, it combines them regardless of
> role (and even if there's no role).
I did a lot of experimenting to get a simple, one-relation-per-direction 
line to render correctly. If I remember that correctly, the "stop" role 
is required ("forward_stop", "backward_stop" or "platform" will also 
work). The tags on the members also seem to matter (e.g. 
amenity=bus_station, even with the correct role, does not get rendered.)


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