On Sun, Aug 30, 2009 at 7:57 AM, John Smith <deltafoxtrot...@gmail.com>wrote:
> 2009/8/30 Anthony <o...@inbox.org>: > > True but the example did not show why that was needed. Looking at > > commercial mapping software, the typical solution is to split the way. > > This whole discussion started because of people wanting to do weird > things to show how a stop sign was applicable to a lane not a way, > there is also cases of other restrictions like maxheight and maxspeed > effecting a lane but not both lanes. It was you who suggested that a stop sign is applicable to a lane not a way. I'd say, like Tobias, that it is applicable to a way and a direction. Where I live we do not have multiple lanes. You park on the side and you drive around parked cars in the middle. With very few exceptions, stop signs don't apply to lanes, they apply to ways and directions. In those few exceptions, it probably makes sense to split the way. In the case of the exceptions I can think of this is especially appropriate because at the spot where the stop sign applies to one lane and not the others the road is divided by a painted median and changing lanes is not allowed. There are probably a small number of exceptions where this is not true, but splitting the way in those cases is harmless. I'm not sure how common maxheight and maxspeed are different when applied to a single way. Maxheight would probably be best accomplished by splitting the way. For maxspeed I'm less sure of what the best solution is, but I'm sure there are many. In most cases, assuming one is free to change lanes, the best solution is probably to simply use the maxspeed of the entire way, regardless of lane. If there are restrictions on changing lanes, the way should be split. If there is a desire to keep the full information, "lanespeed" could be introduced, but I'm not sure what the practical value would be. This ignores the probably more common situation where speeds are different in different directions, though. Technically, if U-turns are not allowed, you probably should split the way, but that might be impractical if the situation is very common. And if U-turns are allowed, on a way with different maxspeeds in different directions, well, I showed a possible solution above. This seems very uncommon. On Sun, Aug 30, 2009 at 7:57 AM, John Smith <deltafoxtrot...@gmail.com>wrote: > 2009/8/30 Anthony <o...@inbox.org>: > > Or traffic cones, or a painted median. Should the ways model the > physical > > or the logical? Again looking at commercial mapping software, the answer > is > > logical. The question they ask is whether or not you're supposed to be > able > > to make turns or change lanes, not what the physical road description is. > > My only experience in this area is with OSM and someone somewhere > obviously decided to do it based on physical, it's certainly less > complicated that way, however we just need to tag some lanes in a > minority of cases for a particular reason, but most of the time all > lanes on the way will be symmetrical and tagging the ways should > cascade down to lanes unless something overrides it. > I really don't see how it's less complicated to use the physical rather than the logical. It's actually much more complicated when you get into the micro areas and you start adding straight lines through a large intersection instead of curved left turns.
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