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 <[email protected]>
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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