On 5 Sep 2009, at 07:50, Sarah Hoffmann wrote:
On Fri, Sep 04, 2009 at 07:42:58PM +0100, Péter Connell wrote:
To not use timetables would case various aberrant behaviours like
routing Yorkshire-Scotland traffic via Settle (side-note: does NRES
still need to be forced to route this way?)
Speed differentials are such that you'd need scheduling information
for
any meaningful set up, e.g. here http://osm.org/go/evjiG2F_- where
the
fastest buses run along the bypass
This problem might be solved by adding approximate travel times to
the routes. While timetables themselves are far to complex to add
to OSM, the time it takes to travel between two stations stays
fairly constant. It might be a nice use for the role in route
relations.
The routing still wouldn't be perfect because change times are
also hard to predict when there is no timetable information.
Nonetheless, it would be immensily helpful to plan travels that
involved multiple modes of transport and multiple operators.
If you ever tried to plan a trip from a small town in France
to a small town in Spain, you will know what I'm talking about.
I see huge mission creep[1] here. Wikipedia defines Misson Creep like
this:
"Mission creep is the expansion of a project or mission beyond its
original goals, often after initial successes.[1] The term often
implies a certain disapproval of newly adopted goals by the user of
the term. Mission creep is usually considered undesirable due to the
dangerous path of each success breeding more ambitious attempts, only
stopping when a final, often catastrophic, failure occurs. The term
was originally applied exclusively to military operations, but has
recently been applied to many different fields, mainly the growth of
bureaucracies.
Now of course the whole story of OSM has been one of huge mission
creep but at some point are we not going to need OpenStreetShedules
(or whatever it is called) and should that not be the place to access
schedules that link neatly to OSM and get updated on a very regular
basis?
Personally I would strongly advocate adding bus stops etc and public
transport routes to OSM because they are the connectors between the
schedules and the physical infrastructure, but where do we stop? I see
a creepage with people adding just a bit more and just a bit more when
I think we all agree that we can't get all the timetable information
into OSM, and even if we could then is it appropriate given that it
changes so often?
Clearly there are many people who want access to all the information,
so all we need to do now is agree where we are wanting to get to and
how the project(s) will be organised. Are we wanting to get to:-
A) A point where all the world's public transport access points (bus
stops,station etc) are in OSM (but not the routes) and then all the
route and other schedule information is available from some other DB
B) A point where all the world's public transport access points (bus
stops,station etc) and all the routes are in OSM and all the other
schedule information is available from some other DB
C) A point where all the world's transport schedules are in OSM and
get updated on a regular basis by Bots?
Personally I think we have already gone past point A and I think that
is good. I am happy with B, but don't think C is right for a couple of
reasons. Firstly it will be a lot of data that most people won't be
interested in and does fit very comfortably in the OSM structure.
Secondly there are good reasons why people might want to use different
timetables (future or past ones) and they will then have to have a
different DB. The main adgument for C) is that OSM is adaptable and
has accommodated additional data in the past, so why do it again?
I suggest that we focus for now on getting all the bus stops and
public transport routes from all of the 85 Google Transit feeds that
are already available for reuse[2] (but only the ones where the
licensing in compatible with OSM) into OSM and then think about
setting up OpenStreetSchedules, OpenTimetableService,
OpenStreetTimetables or whatever to contain all the details we need?
For the time being people can dip into these GTFS data feeds
individually, but in time a single big DB might be useful which can
get to chopped up by country or state as is happening with OSM data.
[1] http://en.wikipedia.org/wiki/Mission_creep
[2] http://www.gtfs-data-exchange.com/
Regards,
Peter
Sarah
I think this is something that road routing software has struggled
with
a while so there may be some helpful potential approaches from there.
Though getting the timetables, however difficult, might still be
easier!
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