Hi Guys I was originally attempting to get all the London Underground Tube stations and Rail stations from OSM ( london xml file )
The issues with the data I have had are : 1) Some stations are tagged as Nodes, some as Ways and some as Relations London Bridge is large area Way: http://www.openstreetmap.org/edit?lat=51.50426&lon=-0.084887&zoom=18 and is tagged as a "building" of type "station" and "railway" "station" Westminister Tube station is tagged as a Node http://www.openstreetmap.org/edit?lat=51.501144&lon=-0.125211&zoom=19 of type "railway" "station" this possibly makes sense to be a Node as its too small to be a Way.. Waterloo station is a Way http://www.openstreetmap.org/edit?lat=51.503282&lon=-0.113125&zoom=18 but this time type "building" "station" ( rather than "train_station" as London bridge is ) ( and also "railway" "station" ) but it's also grouped as a Relation of type "site" "railway_station" Maybe some being Nodes, Ways or Relations makes good sense, but maybe it does not... maybe all stations should be a Node ( London Bridge has no Nodes just a single Way ) and then station buildings should just be buildings.. that would at least be more consistant .. the buildings could always be put into a Relation with the Node if needed ? Also types of "train_station" and "station" etc... should this not be standardised? 2) Stations tagged multiple times (this is a much bigger problem) ! Approximately 75 % of all London Underground Tube stations are tagged with a Node multiple times, the distribution looks like this: 0 times : e.g. London Bridge, this is only a Way there is no Node for either the Rail or Tube 1 single time : this is the rarest case and as far as I can see the correct case Borough, Farringdon, St James' Park, Westminister and a few others are the few single tagged Tube stations in London e.g Farringdon looks fine http://www.openstreetmap.org/edit?mlat=51.52056&mlon=-0.10504&zoom=18 its a single node of "railway" type "station" and has the two "networks" correctly attributed to it of "National Rail;London Underground". The only issue that i can see with Farringdon is as with many other tube stations it has a additional russian name "name:ru" of "Фаррингдон" 2,3,4 or even more tages for the same station .. High Street Kensington : http://www.openstreetmap.org/edit?lat=51.5008&lon=-0.19269&zoom=19 has 4 tags .. each one joined to a rail line Piccadilly Circus http://www.openstreetmap.org/edit?lat=51.510003&lon=-0.134754&zoom=18 is tagged twice ( once under a different way ) Lambeth North is again tagged twice ( once under a way ) http://www.openstreetmap.org/edit?lat=51.499021&lon=-0.112524&zoom=18 Oxford Circus Tube Station is not taged at all. but instead the 4 exits are tagged singularly as type "railway" and "subway_entrance" .. http://www.openstreetmap.org/edit?lat=51.515258&lon=-0.141406&zoom=18 though they all do seem to be grouped into a Relation of "public_transport" "stop_area" Is this level of tagging required, and would an actual "station" tag in the centre of these 4 entrances simply denoting the station itself be better ? ---as it is no station at all is plotted on osm.org Green Park Tube Station is similar again with no tagged station but many tagged entrances https://maps.google.co.uk/maps?client=safari&oe=UTF-8&ie=UTF-8&q=green+park&fb=1&gl=uk&hq=green+park&cid=0,0,15806140768408957347&ei=8To6UcfADM-w7AbP_oHQCA&ved=0CKwBEPwSMAA http://www.openstreetmap.org/edit?lat=51.506934&lon=-0.142474&zoom=18 Waterloo Station is tagged once as a large area Way, and then 5 separate times as well as Nodes detonating a station http://www.openstreetmap.org/edit?lat=51.50246&lon=-0.11246&zoom=17 they are dotted all about the place, some on lower layers, some for one train line or another .. 3 ) Also there is the issue of networks tagging .. Some stations are tagged as "London Underground" or "National Rail" as they should, but some that are both a dual are tagged with two nodes one for each rather that a single node of "National Rail;London Underground" for example. eg Kensington Olympia is tagged twice, once with "London Overground" and once with "National Rail;London Underground" So in conclusion the problems I have found with Rail and Tube stations are : a) Tagged as Ways, Nodes or Relations; sometimes all 3, sometimes just a Node, sometimes a building Way of type "station", but no Node. b) Duplicated stations: sometimes an identical tagging many many many times. Sometimes the Rail and the Tube are placed as separate stations when they should be combined, sometimes there is a Way and also a Node, sometimes there is a station for every Rail line/track that comes into the actual station c) Stations are not taged at all, but instead the exits are all tagged as an exit, that are sometimes grouped as a exit relation d) Inconsistant tagging eg some are "train_station" and others just "station" ( e) odd Russian names for many of the stations ) This is just from the ones I have looked at so far, I will look further in the mean time but asking from the OSM data the position of Rail and Tube stations in London is a very non-trivial task. Is there something missing from my understating, or does a refurbishment of the rail stations data for London needed? maybe something like every station is a single node placed at the approximate center, and then "exits" or station buildings are separately tagged and grouped into relations a long with the original point, and that a standard "station" and not the "railway_station" tag is chosen ? Also do these kinds of issues exist for other cities both around the uk and the data for the rest of the world, and is it limited to stations? Hope this has been helpful & can hopefully can get a discussion going about what i am missing and what might be able to be done to help! Best regards James _______________________________________________ Talk-GB mailing list Talk-GB@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-gb
