[Talk-transit] Proposed additional tags for bus stops and an import of San Fracisco data

[Peter Miller]

I have been looking at the GTFS data for San Francisco over the past  
few days and considering how one could do a bus stops/tram stop import  
for the place and more generally for the GTFS data. However... in the  
process I want to be be 100% clear which road the stop serves and in  
which direction to improve the quality of map rendering which is not  
possible with the current bus stop tagging.

Here is the general bus stop positioning problem for bus stops in osm  
as I see it.

The osm community has agreed to place the bus stop beside the road at  
the place where people wait which is good, however if that stop is  
close to a junction or to two roads that run parallel then it is not  
clear which road it serves.

This is a problem when it comes to creating clear map rendering where  
one wants to snap the stop to correct side of the correct road and not  
left them floating as they are currently. An additional complication  
comes when one wants to position the symbol correctly when the road  
widths on the rendering are exaggerated requiring the node to be  
nudged sideways for it to not appear within the junction itself.

I propose that we formalise a couple of NaPTAN tags into the main bus  
stop schema and try these with a SF import.

'Street' tag: to indicate the name of the associated street
'Bearing' tag: to indicate the direction in which vehicles leave the  
stop, to be clear this is the immediate direction taken, not a sight- 
light to the next bus stop. NaPTAN uses compass points N, NE E etc'.

Here are some examples of where the addition tags are useful. In the  
first case it is not clear without the street tag which of two  
parallel streets are served, and in the second it is not clear which  
of three nearby streets are served.
http://www.openstreetmap.org/browse/node/816289382
http://www.openstreetmap.org/browse/node/817535874


With these tags we should then be able to do an automatically import.  
Here are some initial observations on the data.

In general the data is good except for a few places where there appear  
to be duplicates for some stops in similar but not identical  
locations. This would require a manual clean-up of some busy streets  
following the import.
Stops on either side of the road have the same name. This is not a  
problem if the bearing field is set correctly from the schedule data -  
setting the bearing is non-trivial but can be done.
The stop naming is 'street & street' where the first street name  is  
for the street that the stop serves. This will allow the stops to have  
the 'street' field set.
Sometimes the location of the stop is wrong and places the stop on the  
other side of the road. This can be sorted manually afterwards given  
that the bearing field and street fields will show what is actually  
required.

There is a licensing issue for the SF data which is currently only  
available on a 'limited, and revocable license' which 'does not  
include any right to sublicense'.
http://www.sfmta.com/cms/asite/transitdata.htm

Clearly this is not sufficient as it stands and we would need to get  
approval for what we wanted prior to doing the actual work.



Any thoughts on the tagging proposal?


Regards,


Peter