[Talk-gb-westmidlands] [Talk-transit] NaPTAN bus stop database import - some moreobservations
grand.edgemaster at gmail.com
Wed Apr 1 18:14:34 BST 2009
2009/4/1 Roger Slevin <roger at slevin.plus.com>:
> I would be able to comment more about the missing data and other aspect
> which you and others draw to the list’s attention if I could have a copy of
> the NaPTAN data that has been put through the import process – can you (or
> someone else on the list) either point me to where I can find that specific
> data set … or can send me a copy of the specific data that has been
Currently all data as of 25th March 2009 19:47:46 in the West Midlands
region with the a value of Birmingham (case insensitive) in the Town
I am planning to check to see if we missed any stops, and add any
missed based upon a bbox matching.
> Best wishes
> From: talk-transit-bounces at openstreetmap.org
> [mailto:talk-transit-bounces at openstreetmap.org] On Behalf Of Brian Prangle
> Sent: 01 April 2009 13:41
> To: Talk-gb-westmidlands at openstreetmap.org; talk-transit at openstreetmap.org
> Subject: [Talk-transit] NaPTAN bus stop database import - some
> Some more views and observations on the NaPTAN data import in Birmingham:
> 1. It serves as a great QA on OSM data and shows that in the City
> Centre where we have not been able to get decent GPS traces more accuracy is
> needed so the potential of obtaining aerial photography is great.
> 2. It’s a great impetus to resurvey streets where earlier work
> (potentially inaccurate from NPE tracing, older GPS devices, less points
> collected, inexperience, not realising that roads have a width greater than
> the rendered line so placing bus stops too close to the road etc.) can be
> 3. It’s also a great impetus to improve practice on surveying bus
> stops and be much more precise and comprehensive – also a stimulus to edit
> all those old bus stops where we placed them as a node on the way rather
> than to the side of ways which is our current practice.
> 4. QA works both ways and our surveys should help to improve NaPTAN
> 5. As an exercise(excuse the pun!) I cycled from Acocks Green to
> Moseley and back this morning along the No 1 bus route and surveyed 47 bus
> stops each time standing at the pole(leaning against it – you can’t get
> closer than that!) or underneath the plate at a shelter: 4 bus stops
> coincided within 3-4 m; 17 were “good enough” coinciding <8-10m. That’s
> approx 45%. The rest were out by anything up to 90m or were just missing.
> 6. I think either the pole where there is no shelter or the bus stop
> plate at a shelter should be what we survey – that’s where the
> identification of what we survey is located
> 7. Where a physical stop on one side of the road doubles up for one on
> the other side also – I think we’re OK by surveying and tagging the physical
> one with Andy’s suggestion of a tag opposite=yes. The NaPTAN untagged node
> on the other side can be left in place to indicate the logical
> 8. I like the idea of tagging where the bus stop is set back in a
> “lay-by” from the road which might account for some NaPTAN nodes being some
> distance from the road
> 9. For our purposes “good enough” is probably sufficient rather than
> precise positional detail – I’m of the view that as long the bus stop has
> more or less the right relationships to its surroundings then that’s OK.
> 10. Surprised that there is no data for either the closed Digbeth Coach
> Station which is being rebuilt or the temporary replacement nearby. I
> thought we were importing off-street bus stops? Perhaps the NaPTAN data
> doesn’t exist?
> 11. Can’t find any nodes for taxi ranks – not imported or doesn’t exist
> for Birmingham or I’m not looking hard enough?
> 12. For the few nodes where I’ve estimated the fit between OSM and NaPTAN
> to be “good enough” I’ve merged the nodes deleting the unverified tag and
> editing source tag to v=naptan_import;survey
> 13. Verifying the data is going to be a long, slow process with a lot of
> resurveying needed.
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> Talk-transit at openstreetmap.org
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