[Talk-GB] Road density in Naptan pay scale areas
It occurred to me that the Pay scale areas that arrived with the OSM Naptan import should be fairly thickly populated areas, so those with a relatively low road density would highlight places where there were roads missing from the map, and hence help to prioritise attention on plugging the gaps. So for each Naptan area, I calculated road density as the length of roads in km, divided by the area of the pay scale area in sq. km. I've included motorways (and links), primary, secondary, tertiary, unclassiifed and residential roads. I've not included cycleways, paths and bridleways, etc. The database extract I used is a few weeks old (end Dec 2009), but that shouldn't make a lot of difference (unless someone has added a mass of new roads in a particular area). The result can be seen here. http://www.reedhome.org.uk/Documents/osmembedscale.html?kml=KML/naptan.kml http://www.reedhome.org.uk/Documents/osmembedscale.html?kml=KML/naptan.kml; title=Naptan title=Naptan . The highest quartile of areas (by road density) are shown in blue, then the following quartiles in green, orange and red. In other words red areas have the least road for the area, blue areas have the most, green areas are higher than average, orange lower than average. Looking at the result, the broad pattern is what you would expect, with the south-east of England fairly well covered and gaps further north. But at a detailed level things are not as simple as I had hoped. There is too much variation between the different Naptan areas to make sensible comparisons. Anyway, for what it's worth, this is what it looks like. Maybe someone else will spot a way of making use of the information. ___ Talk-GB mailing list Talk-GB@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-gb
Re: [Talk-GB] Road density in Naptan pay scale areas
Peter Reed wrote: It occurred to me that the Pay scale areas that arrived with the OSM Naptan import should be fairly thickly populated areas, so those with a relatively low road density would highlight places where there were roads missing from the map, and hence help to prioritise attention on plugging the gaps. I'm no maths guru, but I think you've made some inaccurate assumptions here: The accuracy of the PSA's - The Swansea one covers half the bay. fairly thickly populated areas. - I wouldn't say South West Wales is. The density may just reflect that there aren't many roads in those areas. Cheers Dave F. ___ Talk-GB mailing list Talk-GB@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-gb
Re: [Talk-GB] Road density in Naptan pay scale areas
On 19/02/2010 09:49, Peter Reed wrote: Looking at the result, the broad pattern is what you would expect, with the south-east of England fairly well covered and gaps further north. But at a detailed level things are not as simple as I had hoped. There is too much variation between the different Naptan areas to make sensible comparisons. Anyway, for what it's worth, this is what it looks like. Maybe someone else will spot a way of making use of the information. It seems to fit with what we already know about OSM. Guildford's blue, since its roads are all mapped. Birmingham the West Midlands are equally well-mapped, but Mansfield and lots of South Yorkshire aren't. There are some oddities in there -- the area around Fort William and Loch Leven is marked in red, but I wouldn't expect to find a much greater density of roads there. Interesting that the area around Falkirk and Grangemouth is red -- I noticed the absence of any Scottish targets in Andy's list the other day, but given that Glasgow and Edinburgh -- where most people in Scotland live -- are well mapped wasn't overly surprised. Can you update this regularly? -- Jonathan (Jonobennett) ___ Talk-GB mailing list Talk-GB@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-gb
Re: [Talk-GB] Road density in Naptan pay scale areas
Thanks for the comment Dave - I think we are in agreement. The point I was trying to make was that once I had plotted the areas I realised that there were limitations that I hadn't foreseen beforehand. I posted it on the basis that (a) it might be useful for others to know that something doesn't work, and (b) there's a chance that it might spark a better idea. Peter Reed wrote: It occurred to me that the Pay scale areas that arrived with the OSM Naptan import should be fairly thickly populated areas, so those with a relatively low road density would highlight places where there were roads missing from the map, and hence help to prioritise attention on plugging the gaps. I'm no maths guru, but I think you've made some inaccurate assumptions here: The accuracy of the PSA's - The Swansea one covers half the bay. fairly thickly populated areas. - I wouldn't say South West Wales is. The density may just reflect that there aren't many roads in those areas. Cheers Dave F. ___ Talk-GB mailing list Talk-GB@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-gb
Re: [Talk-GB] Road density in Naptan pay scale areas
Thanks to Jonathan too. I can certainly update this occasionally if that would be useful. As it stands, comparisons between different areas are influenced too much by how widely the area is drawn, so Edinburgh for example (which in reality is very thoroughly mapped) looks as though it is below average (orange) because the hinterland around it in the Naptan area is so large. It's a thought that maybe trends over time in the same area will be more useful than comparisons between areas. ___ Talk-GB mailing list Talk-GB@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-gb
Re: [Talk-GB] Road density in Naptan pay scale areas
The Clacton pay scale area will be affected by the straight line used to complete the area, rather than the use of the coastline. This excludes almost all the urban areas that should be included. Ed From: talk-gb-boun...@openstreetmap.org [mailto:talk-gb-boun...@openstreetmap.org] On Behalf Of Peter Reed Sent: 19 February 2010 09:49 To: talk-gb@openstreetmap.org Subject: [Talk-GB] Road density in Naptan pay scale areas It occurred to me that the Pay scale areas that arrived with the OSM Naptan import should be fairly thickly populated areas, so those with a relatively low road density would highlight places where there were roads missing from the map, and hence help to prioritise attention on plugging the gaps. So for each Naptan area, I calculated road density as the length of roads in km, divided by the area of the pay scale area in sq. km. I've included motorways (and links), primary, secondary, tertiary, unclassiifed and residential roads. I've not included cycleways, paths and bridleways, etc. The database extract I used is a few weeks old (end Dec 2009), but that shouldn't make a lot of difference (unless someone has added a mass of new roads in a particular area). The result can be seen here. http://www.reedhome.org.uk/Documents/osmembedscale.html?kml=KML/napt an.kml http://www.reedhome.org.uk/Documents/osmembedscale.html?kml=KML/nap tan.kmltitle=Naptan title=Naptan . The highest quartile of areas (by road density) are shown in blue, then the following quartiles in green, orange and red. In other words red areas have the least road for the area, blue areas have the most, green areas are higher than average, orange lower than average. Looking at the result, the broad pattern is what you would expect, with the south-east of England fairly well covered and gaps further north. But at a detailed level things are not as simple as I had hoped. There is too much variation between the different Naptan areas to make sensible comparisons. Anyway, for what it's worth, this is what it looks like. Maybe someone else will spot a way of making use of the information. ___ Talk-GB mailing list Talk-GB@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-gb
