On Fri, 27 Apr 2012 18:54:26 Ilpo Järvinen wrote: > On Fri, 27 Apr 2012, Andrew Errington wrote: > > A lane count of 1.5 is very confusing. What does it mean? What is the > > width of each lane? Is it really 1.5? Should it be 1.55, or 1.4, or > > 1.6? > > ...No, it's not multiple of some magical "default lane width" like you > imply. But simply _something_ between "normal" lanes=1 and "normal" > lanes=2.
But the width=* tag tells you this. Specifically, the width tag tells you if there will be a problem *for you*. Since I have never met you and I don't know what vehicle you are using it would be presumptious of me to tell you that there are 1.5 lanes. Also, it doesn't make sense to allow lanes=1.5 but deny 1.55, 1.4, 1.68 or any other fractional value. What you are doing is introducing a 'special' value with a special meaning. I think we should try to avoid having to interpret special cases. > > It's more useful to tell me width of the road. Then, if there is one > > lane I can see maybe it's very wide, or if two lanes I can see maybe > > they are very narrow. > > ...But how can I tag you this: A road which is lanes=1+wide _AND_ > lanes=2+narrow at the same time? ...You ask me to provide width and select > one of those two, and that is what I oppose, unless you give me some real > tag that is not width to tell that 'hey, there really isn't lanes marked > (which makes it kind of lanes=1) but two can somewhat fit (which makes > it kind of lanes=2 but not really because it's only "somewhat")'! > > ...What I would not want to do is to tag those lanes=1 because that's > certainly a lie as anyone can clearly see after observing some > bidirectional traffic there. It's not a lie. A single lane may be bidirectional. In fact, in this case you *should* tag it lanes=1. If oneway=yes is not present then it means one bidirectional lane. > > In summary, I think simpler is better. A non-integer lane count is > > useless. Use the width tag. > > I oppose using width tag (at least alone) for this because it won't > convey the double meaning. Some other tag than width and tagging with > lanes=2 perhaps (like I already suggested much earlier)? I don't think there is a double meaning. lanes=1 tells me there is one lane. It does not mean one direction, nor should anyone assume that. I *think* you are saying that lanes=1.5 tells me "this road is not really wide enough for two-way traffic, but there *is* two-way traffic so if there is a car coming the other way you have to wait"[1]. For the purpose of discussion, let us assume that a road of 2.5 m width is too narrow for cars to pass. lanes=1 width=2.5 tells me the same thing (one narrow lane, cars travel both directions, but only one direction at a time). lanes=2 width=2.5 tells me the same thing (two very narrow lanes, cars travel both directions, but only one direction at a time). lanes=1 tells me the same thing (one lane implies cars cannot travel both directions at the same time, but no oneway=yes tag implies cars can travel in both directions. We don't know the width but there must have been a reason for a mapper to tag it with lanes=1). width=2.5 tells me the same thing (no lanes=* tag and no oneway=yes tag implies two lanes, but both must be very narrow therefore cars can only travel one direction at a time). I don't think any of these assumptions are unreasonable, and they don't alter the existing meaning of the tags, which I believe are already quite clear, so we should use them and not alter them with special cases. Best wishes, Andrew [1] I have made this sentence to interpret what lanes=1.5 means. If my understanding is incorrect please state what lanes=1.5 actually means. _______________________________________________ Tagging mailing list Tagging@openstreetmap.org http://lists.openstreetmap.org/listinfo/tagging