Glasgow micro-mapping party Sat 6 November
When: Saturday November 6th 2010 11:00-16:00 Where: CCA: Centre for Contemporary Arts - Electron Club room Contact User:Hawkeye - Tim http://wiki.openstreetmap.org/wiki/Mapping_Party/Glasgow > From: talk-gb-requ...@openstreetmap.org > Subject: Talk-GB Digest, Vol 50, Issue 2 > To: talk-gb@openstreetmap.org > Date: Tue, 2 Nov 2010 07:38:56 +0000 > > Send Talk-GB mailing list submissions to > talk-gb@openstreetmap.org > > To subscribe or unsubscribe via the World Wide Web, visit > http://lists.openstreetmap.org/listinfo/talk-gb > or, via email, send a message with subject or body 'help' to > talk-gb-requ...@openstreetmap.org > > You can reach the person managing the list at > talk-gb-ow...@openstreetmap.org > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of Talk-GB digest..." > > > Today's Topics: > > 1. Visualising speed limits (David Earl) > 2. Re: Visualising speed limits (Andy Street) > 3. Re: Visualising speed limits (Emilie Laffray) > 4. Re: Visualising speed limits (Craig Wallace) > 5. Re: Visualising speed limits (Ian Spencer) > 6. Re: Visualising speed limits (Colin Smale) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Mon, 1 Nov 2010 19:40:38 +0000 > From: David Earl <da...@frankieandshadow.com> > To: Colin Smale <colin.sm...@xs4all.nl> > Cc: "talk-gb@openstreetmap.org" <talk-gb@openstreetmap.org> > Subject: [Talk-GB] Visualising speed limits > Message-ID: > <aanlktimvj0dow2nz=42mxqxdajjwmppzvhqjgztp3...@mail.gmail.com> > Content-Type: text/plain; charset=ISO-8859-1 > > Defaults would have to be set nationally or regionally. > > My TagCentral proposal would address this. > http://wiki.openstreetmap.org/wiki/SotM_2010_session:_Tag_Central:_a_Schema_for_OSM > I really must get round to doing something about it. > > David > > On Monday, November 1, 2010, Colin Smale <colin.sm...@xs4all.nl> wrote: > > On 01/11/2010 19:36, David Earl wrote: > > > > On Monday, November 1, 2010, Andy Allan<gravityst...@gmail.com> ?wrote: > > > > On Fri, Oct 29, 2010 at 9:52 PM, Colin Smale<colin.sm...@xs4all.nl> ?wrote: > > > > On 29/10/2010 22:22, thomas van der veen wrote: > > You might like to take note that nothing is implicit in OSM. There are no > > "defaults" as renderers or other consumers of the map data are unconstrained > > as to how they handle missing tags. Ideally all roads should have maxspeed > > explicitly tagged, even if it could be implied from the road class or other > > information. > > > > I disagree quite strongly on this. I see little point in pointlessly > > adding tags when they there is a sensible default. For example, we > > don't need to tag 98% of roads as "oneway=no", and in the same way we > > don't need to tag 98% of UK residential roads as "maxspeed=30mph". > > > > Life's too short for that kind of tedium. That's why we (actually do) > > have implicit information in OSM. > > > > +1 > > > > David > > > > > > I agree with you both too. I was merely stating (for the benefit of a new > > mapper) that there is no working system of defaults. It would be very > > helpful if such a thing were to exist, but right now, there are no > > defaults. "oneway=no" is a bit of a no-brainer but the majority of > > "unwritten rules" ("implicit information") are not quite as obvious. In > > some cases, the wiki states that certain tags may be implied from others > > (e.g. highway=motorway implies oneway=yes) but these are, in general, > > poorly documented and information is fragmented and not easy to find. A > > welcome exception is the wiki page covering access tags for different > > highways[1]. Renderers or other "users" are just as much free to do their > > own thing as mappers are. The only thing that stops the whole shooting > > match descending into chaos is a set of agreements between producers and > > consumers. If it's not written down, and communicated appropriately, it > > might as well not exist. If you want to be unambiguous, use an explicit tag. > > > > So why not start documenting all these defaults or implied values? Here's a > > few suggestions to get the ball rolling. > > > > highway=motorway ? ?implies oneway=yes, lanes=2 > > highway=*, oneway=no ? ?implies ? ?lanes=2 > > highway=* AND lanes>=2 AND oneway=yes ?implies maxspeed=70mph > > highway=* AND lanes>=2 ?AND oneway=no ?implies maxspeed=60mph > > highway=* ? ?implies maxspeed=60mph > > highway=residential ? ?implies maxspeed=30mph > > junction=roundabout ? ?implies oneway=yes > > > > Colin > > > > [1] > > http://wiki.openstreetmap.org/wiki/OSM_tags_for_routing/Access-Restrictions > > > > > > ------------------------------ > > Message: 2 > Date: Mon, 01 Nov 2010 20:30:59 +0000 > From: Andy Street <m...@andystreet.me.uk> > To: Gregory Williams <gregory.willi...@purplegeodesoftware.co.uk> > Cc: talk-gb@openstreetmap.org > Subject: Re: [Talk-GB] Visualising speed limits > Message-ID: <1288643459.15491.74.ca...@americano> > Content-Type: text/plain; charset="UTF-8" > > On Mon, 2010-11-01 at 16:44 +0000, Gregory Williams wrote: > > Looks great. I think an OpenLayers Permalink anchor would make it even > > better. > > Done. > > Cheers, > > Andy > > > > > ------------------------------ > > Message: 3 > Date: Mon, 1 Nov 2010 23:11:45 +0000 > From: Emilie Laffray <emilie.laff...@gmail.com> > To: Andy Allan <gravityst...@gmail.com> > Cc: talk-gb@openstreetmap.org > Subject: Re: [Talk-GB] Visualising speed limits > Message-ID: > <aanlktimr8vuh1+486z_qtktgy5nx0axxszugw9utz...@mail.gmail.com> > Content-Type: text/plain; charset="iso-8859-1" > > On 1 November 2010 17:57, Andy Allan <gravityst...@gmail.com> wrote: > > > On Fri, Oct 29, 2010 at 9:52 PM, Colin Smale <colin.sm...@xs4all.nl> > > wrote: > > > On 29/10/2010 22:22, thomas van der veen wrote: > > > > > You might like to take note that nothing is implicit in OSM. There are no > > > "defaults" as renderers or other consumers of the map data are > > unconstrained > > > as to how they handle missing tags. Ideally all roads should have > > maxspeed > > > explicitly tagged, even if it could be implied from the road class or > > other > > > information. > > > > I disagree quite strongly on this. I see little point in pointlessly > > adding tags when they there is a sensible default. For example, we > > don't need to tag 98% of roads as "oneway=no", and in the same way we > > don't need to tag 98% of UK residential roads as "maxspeed=30mph". > > > > Life's too short for that kind of tedium. That's why we (actually do) > > have implicit information in OSM. > > > > > +1 > > Emily Laffray > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > <http://lists.openstreetmap.org/pipermail/talk-gb/attachments/20101101/be2b0b8c/attachment-0001.html> > > ------------------------------ > > Message: 4 > Date: Mon, 01 Nov 2010 23:33:07 +0000 > From: Craig Wallace <craig...@fastmail.fm> > To: talk-gb@openstreetmap.org > Subject: Re: [Talk-GB] Visualising speed limits > Message-ID: <4ccf4e33.30...@fastmail.fm> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > On 01/11/2010 19:32, Colin Smale wrote: > > > So why not start documenting all these defaults or implied values? > > Here's a few suggestions to get the ball rolling. > > Implicit speed limits are documented on this page: > http://wiki.openstreetmap.org/wiki/OSM_tags_for_routing/Maxspeed > > Some other defaults (eg for oneway) are listed on this page: > http://wiki.openstreetmap.org/wiki/OSM_tags_for_routing > > Though maybe it would be useful to have a page with a UK specific > summary of all this? Something like "UK roads tagging"? > Similar to the tagging guidelines for other countries: > http://wiki.openstreetmap.org/wiki/Category:Tagging_guidelines_by_country > > > > ------------------------------ > > Message: 5 > Date: Tue, 02 Nov 2010 01:50:52 +0000 > From: Ian Spencer <ianmspen...@gmail.com> > To: talk-gb@openstreetmap.org > Subject: Re: [Talk-GB] Visualising speed limits > Message-ID: <4ccf6e7c.6030...@gmail.com> > Content-Type: text/plain; charset="us-ascii" > > An HTML attachment was scrubbed... > URL: > <http://lists.openstreetmap.org/pipermail/talk-gb/attachments/20101102/278f1edd/attachment-0001.html> > > ------------------------------ > > Message: 6 > Date: Tue, 02 Nov 2010 08:38:53 +0100 > From: Colin Smale <colin.sm...@xs4all.nl> > To: talk-gb@openstreetmap.org > Subject: Re: [Talk-GB] Visualising speed limits > Message-ID: <4ccfc00d.2040...@xs4all.nl> > Content-Type: text/plain; charset="iso-8859-1"; Format="flowed" > > Ian, > > You're right, my detailed knowledge of these things is definitely below > par! I spend too much time outside the UK to follow all this. My > "suggestions" were more-or-less intended to catalyze a discussion so I > am not surprised they are not correct. > > I think your post proves the point I was trying to make. Defaults and > the rules surrounding their use can be complex. If the rules are simple > enough and can be documented, we might get away with it, but then some > of the subtleties might get optimised out of the rules leading to > incorrect inferences if mappers don't put the subtleties back in with > explicit tags. So once again I will make a plea for documenting the > defaults very clearly, and/or explicit tagging. And to be clear, I am > *not* talking about adding oneway=no to almost every way. > > An interesting contrast between the UK and Holland (maybe other > countries as well), correct me if I'm wrong: > * In the UK, you commit an offence (e.g. parking where it is forbidden) > based on a local authority by-law, although the absence of decent > signing could be a valid mitigation. > * In Holland, the offence is to disobey a sign; if it's not signed > (properly), you haven't committed an offence. > > A significant difference, which leads to more consistent, more explicit, > less confusing signage in NL, without having to e.g. measure the > distance between street lights. The "built-up area" starts where the > sign says it does. > > Colin > > On 02/11/2010 02:50, Ian Spencer wrote: > > > > > > Colin Smale wrote on 01/11/2010 19:32: > >> So why not start documenting all these defaults or implied values? > >> Here's a few suggestions to get the ball rolling. > >> > >> highway=motorway implies oneway=yes, lanes=2 > >> highway=*, oneway=no implies lanes=2 > >> highway=* AND lanes>=2 AND oneway=yes implies maxspeed=70mph > >> highway=* AND lanes>=2 AND oneway=no implies maxspeed=60mph > >> highway=* implies maxspeed=60mph > >> highway=residential implies maxspeed=30mph > >> junction=roundabout implies oneway=yes > >> > >> Colin > >> > > > > Someone has not been on their speed awareness course, have they? > > (ahem!) 70mph is based on dual carriageway. A dual carriageway does > > not need two lanes to qualify, and this is more common these days as > > you find that on certain dual carriageways a lane has been blanked out > > for some distance. > > > > Also, to nitpick, your implications are not all correct, oneway=true > > and lanes >=2 does not imply any sort of maximum speed, as any decent > > one-way system in a town would match this, and you cannot rely on a > > trunk road to identify this as truck roads often run through built up > > areas. In other words, there are sensible defaults, but you cannot > > imply speed limits as easily as you suggest from the tags you present > > there. Similarly, although again a sensible default, residential roads > > with 40mph or more are not uncommon. > > > > However, that is pedantic, and I'd agree in principle with defaults > > being sensible, indeed road signage in the UK is based on the > > principle that you can infer the speed limit from the presence or > > absence of street lighting if there are no contradictory speed limit > > signs (motorways being an explicit exception to the rule). This has > > saved me from a speed camera incident or two in the past. > > > > So to go down a proper mapping exercise to determine actual speed > > limits, we should be mapping the limits of street lighting as that is > > the relevant attribute, though to be fair, I can barely recall an > > example where a council has relied on the presence of street lighting > > alone to control traffic speed. > > > > Changes in legislation a few years ago make understanding this > > implicit speed limit more relevant, as it is now no longer a > > requirement to signpost increases in speed limits in certain > > scenarios, not is it a requirement to have signs either side of the > > road in all cases and your only clue might well be that you see a > > repeater sign somewhere up the road - the theory being that when you > > exit a minor road, you carry on at the same limit until you are > > informed otherwise (e.g. exiting on an unlit country lane which was 30 > > mph onto another unlit country lane you might find a repeater sign a > > bit down the road saying 40mph without an intervening speed limit sign > > to show the increased speed. So a little bit of care is needed in > > mapping speed limits to ensure you map based on the subtleties. > > > > Of course, these speeds do not apply to vans which are not car based, > > nor buses and lorries. A surprising number of white van men drive at a > > licence losing 30mph over their 60mph speed limit on dual carriageways > > and 50mph on single carriageways; and perhaps you should not curse the > > lorry on a typical single carriage A road where they are limited to > > 40mph by law, 50mph on a dual carriageway. It gets more interesting > > for lorries on a motorway, because although they are allowed to do > > 60mph in terms of speed limit, lorries now have to have a speed > > restrictor and digital tachograph that limits them to 56mph to comply > > with EU legislation so this is the de facto limit. > > > > So any maxspeed needs to account for the type of vehicle, (or it > > should be a code). This is even more the case in Europe where it is > > common to see sections of autobahn or trunk road where the speed limit > > is explicitly varied by type of vehicle. > > > > FWIW, Tom Tom maps speed changes pretty accurately, though it is not > > completely reliable, but the competition is pretty high. > > > > Spenny > > (currently pointless in mpre ways than one!) > > > > > > _______________________________________________ > > Talk-GB mailing list > > Talk-GB@openstreetmap.org > > http://lists.openstreetmap.org/listinfo/talk-gb > > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > <http://lists.openstreetmap.org/pipermail/talk-gb/attachments/20101102/5f0da3a0/attachment.html> > > ------------------------------ > > _______________________________________________ > Talk-GB mailing list > Talk-GB@openstreetmap.org > http://lists.openstreetmap.org/listinfo/talk-gb > > > End of Talk-GB Digest, Vol 50, Issue 2 > **************************************
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