Apologies form coming into the conversation late( (I have just
returned from the State of the Map conference which was very
impressive as always).
I have been spending some time looking at GTFS stops data for San
Francisco today. There seems to be a problem where there are multiple
stops with the same name, there also appear to be different names for
the same physical stop which may appear multiple times as I don't
believe there are that many actual stops on the ground.
On the junction of Market St & Castro St there are 8 bus stop points
in GTFS
They are called:
Market St & Castro St
Market St & Castro St
Market St & Castro St
Castro St & Market St
Market St & Castro St
Market St & 17th St
Castro St & 17th St
17th St & Castro St
And then the following for metro services (note the names are not that
well chosen as a pair)
Metro Castro Station/Downtown
Metro Castro Station/Outbound
Not all of the above have actual services from them and Google Transit
bails out, merges the services into a smaller number of stops (one for
bus and one for metro) and when one pulls up a service lists them as
'services available from near here'. The full list of stops (some of
which have no services) do however appear on the google streetview
images.
We have experience of the UK NaPTAN database where there is a separate
DB for the stops from the schedules and from the mapping). I would
suggest that:
We recommend that GTFS is modified so that
Stop_ID should ideally be used for a stable authority wide ID for the
stop (or indeed stable national ID)
That there is space for a separate 'indicator' for each of the stop
typically used around for stops around a junction where the name is
the same (possibly A,B,C etc)
That the 'name' of the stops is the same for every stop around a
junction.
At ITO we want to be able to connect stops to the correct side of the
correct street and I think this will be of more general use to other
service providers. This information should not be dependent on a
particular supplier of mapping. We have found the following successful
in the UK and recommend that GTFS allows and encourages suppliers to
include the same information for a stop.
A direction flag (N,NE,E,SE etc) which indicates the direction that
vehicles take when leaving the stop
A street-name which holds the name of the street on which the stop
point appears.
Some time ago I noticed that some providers of GTFS data supply only a
single Stop for use by services in both directions. I suggest that
GTFS recommends (but doesn't require) that a stop is provided for each
direction.
Finally GTFS does not specify where the stop should be located. OSM
uses the place where one waits (the shelter/pole etc) and not the
place where the vehicle stops. Again I suggest that the standard
should recommend this practice. OSM has a separate field to indicate
where on the highway or railway the vehicle stops.
I agree that Stop Areas can often be worked out automatically,
especially if the 'name' is the same for all the stops in the area.
For major interchange then explicit Stop Areas can be useful in a
hierarchy although this is not done well in the UK yet even though it
is possible. I would recommend that GTFS allows one to express a
hierarchy of this sort.
It feels to me that the time is right to have a good push to get these
issues sorted both in GTFS and also in OSM - in particular to use OSM
to grab information about the physical infrastructure and connect it
to the official ID for the stop used by the authority. It will however
take time to get there one city at a time!
Regards,
Peter Miller
ITO World Ltd
On 4 Jul 2010, at 13:16, john whelan wrote:
In the UK streets are tagged with the value on the sign at the end
of the street and this works very well with printed maps. When I
lived in London a group of bus stops might be labeled A-E but in
general bus stops do not have a name or id painted on the bus stop.
Unfortunately UK practice is not followed by other parts of the
world. In Ottawa each bus stop has a four digit number painted on
it in General Transit Feed Specification (GTFS) terms this is known
as the stop_id. The GTFS stop_name value is not apparent to the
mapper.
The GTFS file contains bus stop location information but this
information can be up to 200 meters out. In Ottawa the convention
is to name the stop after the nearest cross street. Add in town
planning where through traffic is discouraged from travelling on
residential roads but footpaths have been placed to give access to
bus stops and you can have two or three different bus stops with the
same stop_name value but different stop_id values.
Does it matter what we call the stop? Well having the stop_id value
available means that local mappers can at least map the bus stops to
the correct location. Without the stop_id value it becomes more
difficult. The current Ottawa GTFS stops.txt file is incomplete,
some stops appear to be missing, mapping with the stop_id makes it
easier to identify them.
We now have applications that process the tags on an osm file.
Maperitive for example will search tags to locate points of
interest. shop=florist finds local florists. There are many GTFS
aware applications that know the GTFS tag names so reusing them in
OSM makes sense. Routing systems for example work better if the bus
stop is in the right place and correctly labeled.
With the NAPTAN import some one decided which NAPTAN field should be
placed in the name tag and I suspect the original field in the
NAPTAN database wasn't simply name.
Locally my personal preference for the name tag would be to
concatenate the GTFS stop_id and stop_name fields but also retain
them as separate tags. That way some one could set up the rendering
rules for bus stops to display either should they wish to do so.
By the way even street name signs are not always simple. In OSM the
rule is to use the name on the street sign at the time of mapping.
Recently in Ottawa there has been a move to bilingual street signs
so Leduc Crescent becomes "croissant Leduc Crescent". If you tag
street name:"croissant Leduc Crescent" then you get into issues of
what do you expect a casual user to enter on a find or search
command adding in that some streets were mapped before the new
street sign rules.
Cheerio John
On 4 July 2010 06:23, Jenny Campbell <jenuk1...@googlemail.com> wrote:
In the UK, following the NAPTAN import, all stops use name, not
stop_name. A name tag on a bus stop implies that the tag is
referring to the name of the stop anyway, no risk of mix ups there!
We use name in the same way for everything else on the map, why
should a bus stop be different?
Jeni
On 01/07/2010 17:08, john whelan wrote:
Since the JOSM plug_in will become the defacto standard since it
will be used by many people who don't read posts here or understand
the issues may I request that it uses the GTFS tag of stop_name and
stop_code rather than the tag of name.
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