Very good thoughts and examples - thanks for that. I fully support you, that the lanes tag should not be another estimation of width. I also agree, that we should not tag lanes, when they are not obvious in some way.
Regarding the example with the parked cars: I think this case should be handled by the parking-tags. If we start to reason "ok, there are two lanes, but as cars are parking here, I dont tag this" it's getting more complicated than necessary. I always recommend "clean" tags: "lanes" count the lanes. End of story. Otherwise we put more meaning in the value as there should be and just like it is right now with lanes=1.5 (-> "there are two lanes, but they are narrow so I don't tag this"). Regarding width:lanes=2.0|2.0 . I don't agree. If the width is evenly(!) distributed over the existing lanes, don't use the lanes suffix, simply tag: lanes=2 and width=4. But if the width is NOT evenly distributed, one has to use the lanes suffix, so width:lanes=2.0|2.75 should never-ever be tagged (only) as width=4.75. One last question: what would you recommend for estimations of the width? width=x together with source:width=estimated or only est_width? Martin 2012/4/22 martinq <[email protected]>: >> I've had a look for uk guidance as the uk's ordnance survey was >> mentioned, and a lot of older uk advice appears based around a now >> historic view that 'cars = saloon cars' and were 1.8m or less. If cars >> were assumed to be 1.8m wide then implied OS figure of 4m for two lanes >> makes sense. > > > I am not sure we should base the lanes tag value on typical car width. > IMO the lanes tag should *not* be another kind of estimate for the width. > > A further problem is the definition: For example the "euro track" has a > maximum allowed width of 2.55m without mirrors (refrigerated ones even > 2.60m). This would be as fair as basis as a "average" car in UK or a UK > guide. And in US or India we may find another situation again. > > My opinion: > If the width of the road can be estimated and no lanes are marked: We should > tag the width (of the carriageway(*)) only (or est_width or > width+source:width) and no lanes tag. > (*) Sadly the width itself is pretty ambiguous tag at the moment (e.g. is it > the width of the complete street or just the carriageway, etc.). But this is > a topic for its own. > > When you look at following example: > http://wiki.openstreetmap.org/wiki/File:Bangalore_India_traffic.jpg > then I conclude: If there are no marked lanes, it lanes gets simply too > subjective. > > My current practice: > On non-residential areas (tertiary, etc.) I typically tag lanes=2 only if > the road allows *two* trucks (that don't require police escort because they > are wider than allowed, means >2.6m) to pass. In my area this means >5.2m. > > In residential areas/streets I omit lanes if they are not marked. Parking > allowance and parking cars on the street/carriageway make the situation very > complicated. Look here: > > http://bit.ly/I2hna7 > While the carriageway in this example is more than 6m wide and allows two > trucks to pass, you also see parking cars in this street (I don't know the > German law, but they might be allowed to do that). What would you do now? > And if the parking allowance is time limited? For me lanes is simply not > applicable here. > --> I would tag the parking information with parking:lane, width, but not > lanes. > > What I also propose: If lanes are marked, but narrow for trucks (e.g. just > 2m each), I would tag them width:lanes=2.0|2.0 now. If there is a dedicated > maximum width road sign --> maxwidth. > > >> Though I'd think a road 4.3m wide would >> fall under the 'lanes=1.5' idea > > [...] > >> After reading through these emails I'm beginning to think the >> lanes=1.5 would less confusing for narrow two lane roads. > > > -1 > > 1.5 makes no sense. If we can agree that a lane is a "strip, which is wide > enough for one moving line of motor vehicles other than motor cycles" (from > the Vienna Convention of Road Signs, used as basis for local law in many > countries all over the world) -- then either one line of vehicles can move > -- or two. > > --> For me this lanes=1.5 is a clear indication for an attempt to turn the > lanes tag into a rough width-estimate. I think the width tag is the better > tag for width-estimates. > > martinq > > > _______________________________________________ > Tagging mailing list > [email protected] > http://lists.openstreetmap.org/listinfo/tagging _______________________________________________ Tagging mailing list [email protected] http://lists.openstreetmap.org/listinfo/tagging
