Re: [talk-au] What gives with roundabouts?
Sean <4ey0ll...@sneakemail.com> wrote: > I never said I was mapping for a particular program or device. Garmin > was just an example. I'm mapping for all programs and devices. As all > programs or devices can render a loop way it just makes more since to > do it that way. I don't know of any devices that consume OSM data without some kind of conversion process. That conversion process is the only way to relate OSM data to a particular device. So the representation of data in the OSM database really doesn't matter to any end devices, only to the conversion. It's relatively easy for a converter to take, for example, a node tagged mini_roundabout and substitute a small circular way if that makes sense for the destination device/format. It's very difficult (call it impossible) to go back the other way for a device that does actually understand what a roundabout is. What you are advocating removes a tag that means something, whatever that is defined to mean, and replaces it with something that means nothing in the best case, and is confusing (to the device, hopefully not the human operator, but then hopefully they're driving, not looking at the device) in the worst case. It's nearly always best to keep as much meaning as possible in source data. -- Sam Couter | mailto:s...@couter.id.au OpenPGP fingerprint: A46B 9BB5 3148 7BEA 1F05 5BD5 8530 03AE DE89 C75C signature.asc Description: Digital signature ___ Talk-au mailing list Talk-au@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-au
Re: [talk-au] What gives with roundabouts?
bluemm1975-...@yahoo.com wrote: > I thought the same when I first started mapping, as I wanted to show > centre & pedestrian islands like in the Melways. But the wiki is very > specific http://wiki.openstreetmap.org/index.php/Tag:junction%3Droundabout > It says that normal pedestrian islands aren't meant to be drawn as two > separate ways (flares). The lack of ability to draw the little pedestrian islands has always bugged me - I think it should be marked somehow (on roundabouts and on normal t-intersections). It's one of the things I really like about the Melways (I reckon they are probably the best street maps I've ever come across in terms of layout and detail). On the subject of roundabouts, there's a certain irony in using four nodes to create a square, and calling it round... Matt ___ Talk-au mailing list Talk-au@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-au
Re: [talk-au] What gives with roundabouts?
On Mon, 15 Dec 2008 12:08:54 +1100 Ian Sergeant wrote: > + When you cross this kind of roundabout when cycling, or with a > learner driver, you don't have to worry about the characteristics of > the road you are crossing (since you never turn into the traffic of > the cross road, you just cross the roundabout). This isn't just > about cyclists and learners. Its about the nature of the intersection. I'm having quite a bit of trouble understanding your point here, what difference does whether it's a node or a loop-way have on the characteristics of the side road? What difference does the size of the roundabout have to do with this? Surely you *do* turn into the traffic of the cross road, twice in fact, once for each direction, once yielding, once with right of way? Again this happens for all sizes of the roundabout. (In fact I thought that was the point of roundabouts, to reduce the points of contact to a minimum and make the laws of yielding right-of-way very clear - and to slow you down whilst doing it of course) > + It represents what is on the ground accurately. Often there is > less of an actual diversion than many other traffic calming devices, > which are not mapped. To draw it as a deviation in the road, just > isn't what is there. The only other traffic calming device I can think of that this applies to is a 'chicane', perhaps I missed a few options? Humps and their variants cause no change in the traffic flow, neither do Chokers (all listed in map features), what others are there? Given nearly all small roundabouts occupy close if not the entire road width, using the intersecting roads carriageway as part of the loop, this means the average deviation is about 1/2 a road width out and 1/2 a road width back or nearly 1 whole road width. I'm pretty sure I haven't seen a chicane deviate more than a road width (that would put you on the footpath at some point), so it's really a close call here as to whether there is '*less* of an actual diversion than *many* other traffic calming devices'. > + These have a very standardised appearance, and should be > represented in a standardised way, like a template. The benefit > isn't just in time-saving, but in identifying that all these > roundabouts are very much the same. What standard things about a suburban roundabout are there that don't equally apply to a large roundabout? The only standard things I can think of about all suburban roundabouts are: (1) They go clockwise around a central raised island (2) All approaches to the road are divided by at least a smaller splitter island (3) They have one lane (4) They have a roundabout sign displayed on all approaches Beyond this they are as varied as everything else on the planet. The only one of those that doesn't also apply to much larger roundabouts is (3) but it applies to some much larger roundabouts, so it's a bit of a non-starter. If we look at the things that vary between suburban roundabouts we find the following list: (1) The structure of the centre varies wildly beyond being raised: - some have a garden bed, some are paved, some are dirt - some are a single tier, some a 2-tiered, some are 2-tiered with the lower tier being traffic-able. (2) Some have extensive street furniture in the centre, some don't. (3) The splitter islands may or may not have signage. (4) The outer edges of the approach roads may or may not has extra curbing added to tighten the road approaches (5) The roundabouts may occupy just the existing road surfaces or may extend out beyond them, and given the variety in road widths different approaches to the same road can yield radically different judgements by people. (the extended area is often quite large on the opposite side of a 'side' road in a T-junction) (6) Not all of these are even circular, some are elliptical in shape, and of course there's the classic egg-timer shapes. (7) Quite a number of circular ones have funny offsets on opposite roads which mean your have to adjust the centre lines of the adjoining ways to make it line up (suddenly map doesn't match ground any more). 6 and 7 at least can be handled by actually drawing the roundabout as a way I guess, but then it defeats the purpose of the standardisation idea. I'd suggest in fact that suburban roundabouts don't fit any kind of template at all. the rest for now because you raise a good point about the decision order, in fact I'd even go so far as to suggest (given jackb's disagreement with me on what it means) we need to make an explicit list of what exactly defines a roundabout, I think Liz's list at the top of her PDF was a good start, plus a no-parking addition). -- =b ___ Talk-au mailing list Talk-au@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-au
Re: [talk-au] What gives with roundabouts?
On Mon, 15 Dec 2008 00:22:05 -0800 (PST) bluemm1975-...@yahoo.com wrote: > > So after realising this I can't actually stand in support of > > junction=roundabout on a point (or some other similar proposal) as a > > permanent fixture, but would fully support it as a 'temporary' tag > > to indicate at some point someone with my kind of island obsession > > comes along and puts in the details. > > I thought the same when I first started mapping, as I wanted to show > centre & pedestrian islands like in the Melways. But the wiki is very > specific > http://wiki.openstreetmap.org/index.php/Tag:junction%3Droundabout It > says that normal pedestrian islands aren't meant to be drawn as two > separate ways (flares). I guess you need to add a comment to the > discussion page or on Talk mailing list to propose something > different. Therefore given the wiki definition, there isn't anything > gained by having 4+ nodes when compared to a point and some kind of > diameter value. I think perhaps you miss-understood me, or perhaps judge my island obsession a little too extreme. I wasn't actually talking about those island which I personally don't draw until they're at least a car length or so, big enough to get in the way of a u-turn or obstruct you turning into a driveway off the side of the road. (obviously not right on a roundabout, but that's what I use as a rule-of-thumb idea about which islands to include). You say given the wiki definition there isn't anything to be gained, yet the wiki definition says: "A standard size roundabout with up to four exits can be drawn simply using four nodes in a diamond shape." To me that sounds like the definition says a roundabout is four nodes. -- =b ___ Talk-au mailing list Talk-au@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-au
Re: [talk-au] What gives with roundabouts?
--- On Sat, 13/12/08, Darrin Smith wrote: > I'm totally on your wavelength with respect to the making our usage > match the worlds usage, and making a new tag when we have something > different, and I get the impression a couple of others on here have > similar opinions in a general sense. > > However (isn't there always a However, or a But or some such thing ;)... > > I've been thinking about my stance with this and I think I've distilled > why it's been bugging me. I tend to make sure that any reasonably size > island of any sort is represented by separating the ways since > said island is blocking normal traffic movement between the 2 > carriageways (about the only ones I skip are the small lane separator > islands you get on the side roads in some small T-junctions, but I'll > clock that up to my laziness ;). So given even the smallest > roundabouts are islands of quite a large size I like to see them > represented on the map as a separating of the ways. > > So after realising this I can't actually stand in support of > junction=roundabout on a point (or some other similar proposal) as a > permanent fixture, but would fully support it as a 'temporary' tag to > indicate at some point someone with my kind of island obsession comes > along and puts in the details. I thought the same when I first started mapping, as I wanted to show centre & pedestrian islands like in the Melways. But the wiki is very specific http://wiki.openstreetmap.org/index.php/Tag:junction%3Droundabout It says that normal pedestrian islands aren't meant to be drawn as two separate ways (flares). I guess you need to add a comment to the discussion page or on Talk mailing list to propose something different. Therefore given the wiki definition, there isn't anything gained by having 4+ nodes when compared to a point and some kind of diameter value. BlueMM Start your day with Yahoo!7 and win a Sony Bravia TV. Enter now http://au.docs.yahoo.com/homepageset/?p1=other&p2=au&p3=tagline ___ Talk-au mailing list Talk-au@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-au
