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: [email protected] [mailto:talk-gb- >[email protected]] On Behalf Of Brian Prangle >Sent: 01 April 2009 1:41 PM >To: [email protected]; [email protected] >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. _______________________________________________ Talk-transit mailing list [email protected] http://lists.openstreetmap.org/listinfo/talk-transit
