[Talk-gb-westmidlands] NaPTAN bus stop database import - some moreobservations

[Andy Robinson (blackadder-lists)]

And I've just done the same for all 50ish stops in Sutton Coldfield Locality
over lunch. I'll drop the results in as soon as the edits done but I am
generally concurring with Brians observations. What was most interesting is
that about 20% of the stops in the locality have no physical bust stop on
the ground.
(http://www.itoworld.com/product/naptan/describe_feature?id=LOE0032018)

More later

Cheers

Andy

>-----Original Message-----
>From: talk-gb-westmidlands-bounces at openstreetmap.org [mailto:talk-gb-
>westmidlands-bounces at openstreetmap.org] On Behalf Of Brian Prangle
>Sent: 01 April 2009 1:41 PM
>To: Talk-gb-westmidlands at openstreetmap.org; talk-transit at openstreetmap.org
>Subject: [Talk-gb-westmidlands] NaPTAN bus stop database import - some
>moreobservations
>
>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. Its 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
>improved.
>3. Its 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 data.
>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 cant 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. Thats 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 thats 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 were OK by surveying and tagging the physical one
>with Andys suggestion of a tag opposite=yes. The NaPTAN untagged node on
>the other side can be left in place to indicate the logical relationship.
>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 Im of the view that as long the bus stop has more or less
>the right relationships to its surroundings then thats 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
>doesnt exist?
>11. Cant find any nodes for taxi ranks not imported or doesnt exist for
>Birmingham or Im not looking hard enough?
>12. For the few nodes where Ive estimated the fit between OSM and NaPTAN to
>be good enough Ive 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.