When you have a dual carriage road, the sidewalk=left/right/both is ambiguous.
I’ve seen a lot of city accessibility analyses that compare the presence of sidewalks (partial: left or right, and complete: both) between districts, regions or cities, and I felt it was way more accurate to count the other side of the dual carraige as the “other sidewalk”. So if you have a dual carraige with sidewalk on the right of the forward side, and on the right of the backward side, I think it should be sidewalk=both for both direction, otherwise, you get innaccurate representation of “on-the-ground truth about sidewalks on streets”. There is almost no such thing as sidewalks in the middle of a traffic island. Also, when the sidewalk is only in one direction, i feel like it should be tagged as sidewalk=right on the side with the sidewalk and sidewalk=left for the opposite direction.
What do you think?
I added a section in the sidewalk wiki page about this, but it was asked to include the community in the discussion to get a consensus if possible: Sidewalks - OpenStreetMap Wiki .
Right, but if there is one, how would you tag it? In bigger European cities, having a strip of green to boule, uh … walk on between the two parts of a dual carriageway is actually a thing. Your suggestion would make it impossible to distinguish between 2 and 3 sidewalks. I know that, ultimately, separate sidewalks would be the way to go, but even then, you gotta ask yourself the question: sidewalk:both=separate or sidewalk:left/right=separate?
Yes the same applies to separate tag. The fact that there could be a sidewalk in the middle is so rare that I feel it would be ok that this case would have to be analyzed with spatial analysis checking for the presence of a footpath in the middle, like an exception.
In Montreal, we tag the separate sidewalk with sidewalk:both=separate if there is sidewalk on the right of both direction, and sidewalk:left=separate, sidewalk:right no and the reverse version if there is only a sidewalk on the right of a single direction.
But wouldn’t that imply that pedestrians can walk along the carriageway with no sidewalk, whereas in reality they would have to cross two carriageways and a median to reach a sidewalk? It seems to make things more difficult for routers, for example. How would they know that the referenced sidewalk is not actually alongside the way?
In North American, there are a lot of these stroads with dual carriage and pedestrian are used to the fact that the sidewalk is never in the middle. Would you have examples of places where it would not be obvious?
I disagree, and I mapped in way to indicate that one side has separately mapped sidewalk and one side has no sidewalk.
note that in this case we place tags on carriageway, not on entire road
feel free to add dual_carriageway=yes to denote that onesided sidewalks are expected (or assume that all oneway=yes or oneway=-1 road are dual carriageway, maybe assume that only for major oneway roads).
Bulevar Adolfo Suárez, for example, has a kind of garden/park area in the middle with a footway. This is a newly constructed boulevard.
A more traditional example would be O’Connell Street in Dublin which has a wide paved area between the two carriageways.
More generally, many dual carriageways also have parallel service roads or are mapped with more than 2 parallel ways for various reasons. It seems difficult to me to accurately reflect all those circumstances if the sidewalk on a way reflects anything other than the way itself. It may be the case that a pedestrian would recognise they need to cross the whole road once they get there, but it still feels like routing could be misleading if the router doesn’t know which way actually has the sidewalk.
OK, but how do you propose people analyzing sidewalk accessibility know if the street has sidewalks on both sides or only on one side? A lot of analyzes are done on these data to compare cities and regions. This gives wrong results.
I guess if you’re only concerned with a particular region, you could ensure consistent coverage of dual_carriageway=yes to know when to count the length of sidewalk:both=separate once or twice.
feel free to add dual_carriageway=yes to dual carriageway roads to denote that onesided sidewalks are expected (or assume that all oneway=yes or oneway=-1 road are dual carriageway, maybe assume that only for major oneway roads).
OK, but is there some info in the wiki that explains all this? Because I did not find any info on sidewalks with dual carriage and like a lot of people, we assumed the left and right sides were the one from the opposite direction and not the middle median. If I ask someone walking on local dual carriage road in the city if there are sidewalks on right and left side of opposite direction, they will tell me, yes for sure, there are sidewalks on both sides and not assume there should be one in the median to count.
I have been mapping sidewalks the way I explained on dual carriage for years now, but a new user reverted most of the sidewalk tags in my area, so I though maybe it was not obvious, but now, I just see I was misleaded and the opposite was to be obvious. I feel weird…
