Re: [talk-au] traffic lights on dual carriageway intersections
"Steer" wrote: I have been trying to find the accepted practise for mapping traffic lights where dual carriageways interest. There is much discussion on various sites, but most seems to be a bit old, and I’m not convinced I’ve found what is the latest accepted practise. I checked some intersections in Melbourne’s CBD, and the method I saw that I liked and thought the best was where there were 4 lights at the intersection, but they were not placed on the intersecting modes, but one node back “upstream” on each way. I think this is good because no matter which way you go through the intersection, you only pass one set of lights (rather than 2 if they were placed on the actual intersecting nodes). Any comments? I have always entered such traffic lights on dual carriageways in the way you describe. This is because: 1. The "traffic light count" along a section of road is then accurate, and 2. It's the accurate representation of what's on the ground. It lets us convey the significance of the stop lines associated with the lights. That's something we can't do with two-way traffic without compromising point 1. I have argued this position on previous occasions. John ___ Talk-au mailing list Talk-au@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-au
Re: [talk-au] traffic lights on dual carriageway intersections
And the only area it's done like this is in Melbourne. Cheers Ross On 03/11/12 17:03, John Henderson wrote: "Steer" wrote: I have been trying to find the accepted practise for mapping traffic lights where dual carriageways interest. There is much discussion on various sites, but most seems to be a bit old, and I’m not convinced I’ve found what is the latest accepted practise. I checked some intersections in Melbourne’s CBD, and the method I saw that I liked and thought the best was where there were 4 lights at the intersection, but they were not placed on the intersecting modes, but one node back “upstream” on each way. I think this is good because no matter which way you go through the intersection, you only pass one set of lights (rather than 2 if they were placed on the actual intersecting nodes). Any comments? I have always entered such traffic lights on dual carriageways in the way you describe. This is because: 1. The "traffic light count" along a section of road is then accurate, and 2. It's the accurate representation of what's on the ground. It lets us convey the significance of the stop lines associated with the lights. That's something we can't do with two-way traffic without compromising point 1. I have argued this position on previous occasions. John ___ Talk-au mailing list Talk-au@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-au ___ Talk-au mailing list Talk-au@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-au
Re: [talk-au] traffic lights on dual carriageway intersections
On 3/11/2012 5:33 PM, John Henderson wrote: I checked some intersections in Melbourne’s CBD, and the method I saw that I liked and thought the best was where there were 4 lights at the intersection, but they were not placed on the intersecting modes, but one node back “upstream” on each way. I think this is good because no matter which way you go through the intersection, you only pass one set of lights (rather than 2 if they were placed on the actual intersecting nodes). I read it and liked it but then poked around near me but found that traffic signals where a divided road meets and undivided road, the undivided road gets a count of two. You could put the undivided (two ray) road traffic signals in the centre of the intersection but that starts to look pretty strange. Which then leads us to possible accusations of mapping for the "routing renderer". Strictly speaking the traffic lights are things on poles placed on traffic islands as well as overhead gantries. Should we be tagging the physical object, ie. the signal rather than its effect which is most pronounced at the stop-line? Another thought would be to tag the stopline with a direction tag to hint the renderer that a vehicle would stop here moving in a particular direction..starts to get complicated. What about wig-wags outside fire-stations or supplementary traffic signals applied to a level crossing. Starts to get tricky.. Still worth thinking about... Alex ___ Talk-au mailing list Talk-au@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-au
Re: [talk-au] traffic lights on dual carriageway intersections
On 03/11/12 18:03, John Henderson wrote: 2. It's the accurate representation of what's on the ground. It lets us convey the significance of the stop lines associated with the lights. That's something we can't do with two-way traffic without compromising point 1. Mapping is choosing a representation of what is on the ground. By choosing to place traffic light not on the intersection node, you are failing to represent that "this is an intersection of two roads, controlled by traffic signals". Instead you are choosing to represent "There is a stop line here and traffic signal and further on there is an intersection". So, ideally we should have a rich enough mapping set to allow us to indicate both. However, since we can currently represent only one, I currently feel that it is far more important to indicate that the intersection is controlled, than the location of the traffic signals, or an accurate count of traffic signals. This is especially true, since in the general case (non-dual carriageway) we can't represent these things anyway. So, even if we favour the stop line location/traffic signal count method, it will always be wrong and unreliable. Ian. ___ Talk-au mailing list Talk-au@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-au
Re: [talk-au] traffic lights on dual carriageway intersections
On 04/11/12 07:29, Ian Sergeant wrote: By choosing to place traffic light not on the intersection node, you are failing to represent that "this is an intersection of two roads, controlled by traffic signals". Instead you are choosing to represent "There is a stop line here and traffic signal and further on there is an intersection". We have different intuitions about what's important here. John ___ Talk-au mailing list Talk-au@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-au
[talk-au] 4WD only tags
Hi David, just my 2 cents on 4WD_only tags. By adding a 4x4 recommended tag will add to the complexity because it's kind of subjective as to which roads/tracks are traversable in a 2WD vehicle, therefor adding another option for this key will further complicate the issue. Li. ___ Talk-au mailing list Talk-au@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-au
Re: [talk-au] 4WD only tags
Li, I beg to differ. While I agree that grading of a 4x4 track is subjective, so is much of the other data in the OSM database. Must be that way. The real issue is how important the data is. As I have mentioned, I am concerned that maps are being rendered that ignore this data. Routing engines are potentially sending people down roads that they, and their vehicles are ill suited to. Bad things will definitely happen. The routing people are saying "but these tags don't even show on the OSM maps, why should we worry ?". And as to subjective, while there will always be borderline cases, I don't think it would be too hard to divide tracks up into - * 4x4 recommended - you will might be OK in a conventional car or (better still) an SUV but you have been warned. * 4x4 required - you really need a stock 4x4, a real one with (eg) low ratio. * 4x4 extreme - this is for the death or glory boys, they need experience and modified vehicles. This is a recent addition ! I am pretty sure that if you and I spent a couple of weeks having some driving fun, we'd agree on the vast majority of the tracks we graded. David - Original Message - From: "Li Xia" To:"David Bannon" Cc:"OSM Australian Talk List" Sent:Sun, 4 Nov 2012 13:08:22 +1100 Subject:4WD only tags Hi David, just my 2 cents on 4WD_only tags. By adding a 4x4 recommended tag will add to the complexity because it's kind of subjective as to which roads/tracks are traversable in a 2WD vehicle, therefor adding another option for this key will further complicate the issue. Li. ___ Talk-au mailing list Talk-au@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-au
Re: [talk-au] 4WD only tags
David, When we first proposed (and started using) the 4wd_only tag, there was a lot of pushback from people who complained that it was not a verifiable tag. Track type had the same response. We were able to show them that there are signs all over Australia that say 4WD only at the start of a road. I think you'll get a lot of reaction trying to add levels of 4WD required where there are no signs to point at. Feel free to advocate it, though, and to tag that way. If enough people tag things in a certain way, that's the surest way of setting a standard. Stephen On 4 November 2012 13:41, David Bannon wrote: > > Li, I beg to differ. While I agree that grading of a 4x4 track is > subjective, so is much of the other data in the OSM database. Must be that > way. > > The real issue is how important the data is. As I have mentioned, I am > concerned that maps are being rendered that ignore this data. Routing > engines are potentially sending people down roads that they, and their > vehicles are ill suited to. Bad things will definitely happen. > > The routing people are saying "but these tags don't even show on the OSM > maps, why should we worry ?". > > And as to subjective, while there will always be borderline cases, I don't > think it would be too hard to divide tracks up into - > > * 4x4 recommended - you will might be OK in a conventional car or (better > still) an SUV but you have been warned. > > * 4x4 required - you really need a stock 4x4, a real one with (eg) low > ratio. > > * 4x4 extreme - this is for the death or glory boys, they need experience > and modified vehicles. This is a recent addition ! > > I am pretty sure that if you and I spent a couple of weeks having some > driving fun, we'd agree on the vast majority of the tracks we graded. > > David > > > > > - Original Message - > From: > "Li Xia" > > To: > "David Bannon" > Cc: > "OSM Australian Talk List" > Sent: > Sun, 4 Nov 2012 13:08:22 +1100 > Subject: > 4WD only tags > > > > Hi David, just my 2 cents on 4WD_only tags. > > By adding a 4x4 recommended tag will add to the complexity because it's > kind of subjective as to which roads/tracks are traversable in a 2WD > vehicle, therefor adding another option for this key will further > complicate the issue. > > Li. > > > ___ > Talk-au mailing list > Talk-au@openstreetmap.org > http://lists.openstreetmap.org/listinfo/talk-au > > ___ Talk-au mailing list Talk-au@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-au
