Il giorno mar 12 nov 2019 alle ore 23:54 Nick Bolten <nbol...@gmail.com> ha scritto:
> You make a very good point! A road can have a pedestrian lane, shoulder, > both, or neither, so it wouldn't make any sense for a pedestrian lane to be > a type of shoulder. The widths do vary quite a bit as well, regionally. > > > You mean a situation like this?: > > > https://wiki.openstreetmap.org/wiki/File:Sidewalk_and_crossing.svg > > One very similar to that, yes! I think I normally wouldn't add > sidewalk=both to any length of the highway=residential. Is that a typical > thing to do? I would assume that meant the highway=residential street had > its own short piece of sidewalk, when it actually doesn't. > > The challenge I'm describing is in reliably associating the crosswalk with > the pedestrian paths. After all, the crosswalk is a node on a different > street way. I know that I could do it 99.x% of the time, but it will > require using some graph traversal approaches that most people aren't > familiar with. Plus, those cases where I couldn't reliably determine it > could be very important. I suspect this is one of the reasons I haven't > found anyone using these data in concert (sidewalk=both + highway=crossing) > to do pedestrian routing. > > Mapping for a router isn't the end-all-be-all of this kind of data, of > course, but it is one thing that would be hard to do with this tagging > schema. I'd be interested to know if there are other data consumer plans > for the data, since use does dictate what the schema looks like. Making > streets be ways was a conscious choice informed by routing, for example! > I didn't know that representing streets as lines was a choice made to support routing Interesting This made routing for cyclists, pedestrians and impaired people more difficult And I hope everyone can see why that's disappointing Choosing a representation always has political effects In this regard, I find this talk quite on point http://opentranscripts.org/transcript/programming-forgetting-new-hacker-ethic/ > > I would simply connect the sidewalk way with the road where the > sidewalk ends (and map a barrier=kerb + kerb=* node) and add > pedestrian_lane=* to the road starting from where the pedestrian lane > begins. > > So there would be a segment of footway=sidewalk that is not actually on a > sidewalk? I've been unsure about what to do in similar situations, like how > to connect footways to roads without implying there's literally a footway > on top of the road. Probably worth its own, separate discussion (it was > discussed previously, but without conclusion), so I won't elaborate. > > > There is a pedestrian lane along the the south-eastern part of the road > Reichenbachstrasse. On the opposite side there are public steps as well as > many (currently unmapped) driveways and private footpaths. Mapping the > pedestrian lane as a separate way would either make it disconnected from > the steps, driveways and footpaths on the opposite side of the road or you > would need to add many highway=footway connections from the pedestrian lane > to the steps, driveways and footpaths, which would make the map very > confusing. > > > Therefore i strongly advise against mapping pedestrian lanes as separate > ways. > > > By the way, the same problem occurs with sidewalks mapped as separate > ways. > > Yes, it's a trade-off: the actual pedestrian path's primary connections > and attributes vs. its association with the street. Neither are actually > perfect options, which is why I'm suggesting the possibility of redundant > tagging. Ideally, we'd come up with a universal strategy for relating these > ways together, but I don't want to monopolize this proposal! > > > I'm not a programmer and therefore don't have concrete plans to use this > data, but i imagine (and hope) that pedestrian routers could use this data > to prioritise roads with pedestrian lanes and to tell blind people on which > side of the road they should walk. > > Maybe it would be helpful to set up a meeting with some organizations that > serve the visually impaired along with programmers that build routing > software. We (Taskar Center) might be able to help with that sort of > meeting, and it would be even better to have organizations from different > cultures and geographies involved as well. As-is, I think the challenge of > reliably associating paths with crosswalks is a big one for mapping for > routing for the blind. > > There are 2 talks given at the last osm2019 that I think are on par with what you are thinking You might want to get in touch with their authors This is the first one: Pedestrian Routing The author argues like effective pedestrian routing in which the author argues how a previous focusing on routing for cars has made pedestrian routing more difficult (and he presents a quite complicated algorithm for extracting information useful for pedestrian routing) https://media.ccc.de/v/sotm2019-1265-routing-for-humans The second one is this one: Is the OSM Data Model creaking ? The author is involved in a prominent routing service for cyclists and he makes the point about how effective routing for cyclists is very hard to impossible https://media.ccc.de/v/sotm2019-1038-is-the-osm-data-model-creaking- I' m very interested in these issues too I hope that the idea of representing streets as areas can help (as hinted in the talk about the data model creaking) Hope this helps
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