[Tagging] sidewalk unsuitable for wheelchair

[José G Moya Y.]

I opened a similar thread in october. The origining fact was a sidewalk
having a stair, where the other sidewalk had a ramp.
I was suggested to map the sidewalk as a separate object.
Yours,
José.

El 10/12/2017 20:32, "Nick Bolten" <nbolten at gmail.com> escribió:

> > the basic rendering issue where streets already collide with buildings
>
> The renderer can always be updated to accommodate any issues with showing
> where sidewalks exist. This is a situation of having more information
> available for display, and how to organize it, which isn't a bad thing. For
> example, you could put `footway=sidewalk` ways at a lower z-level and have
> basically zero impact on street rendering.
>
> > where do I put the crossings other than make them up?
>
> All crossings are made-up, but some have markings that make it easier.
> Where you put them depends on local laws and mapping considerations, but at
> least having them connect around every intersection is good practice.
> F> A pedestrian can cross the road anywhere and will not want a route
> that does not allow that most basic of concepts.
>
> This varies geographically quite a bit, and there are very few routes that
> would be improved by adding this consideration. Or, in other words, how
> often do real routes need someone to cross at arbitrary locations, with
> basically zero metadata to assist with safety / mobility infrastructure?
> Examples:
>
> 1) Your origin and destination are very close together and you have no
> mobility preferences except 'walking'. In this case, routing and sidewalks
> are pointless, just draw a line from A to B. Several routers make that
> interpretation already.
> 2) There are several 'shortcuts' along the optimal path, such as alleys,
> and one might expect that the router would keep having you go out of the
> way to use intersections. Alleys would naturally be connected to streets
> and intersect with sidewalks, so these paths *will* be followed so long as
> the router allows short trips on streets/driveways (most do).
> 3) There exist common entrances to parks / other footways that involve
> crossing the street. In this case, it would of course make sense to add a
> crossing way.
>
> Finally, tagging streets with `sidewalk=*` has these same issues. In order
> for routing to actually use the information to figure out how
> infrastructure is connected, it has to make an expanded graph that maps
> sidewalks and how they're connected, and you're back to any potential
> issues with mapping sidewalks as separate ways, but you now have
> lower-quality information to work with. The ability to "cross the street
> anywhere" doesn't really exist in most routers, because they're really just
> treating you like a car that moves slower, and crossing (and the sidewalk,
> typically) doesn't exist at all in that paradigm.
>
> On Sun, Dec 10, 2017 at 10:46 AM Philip Barnes <phil at trigpoint.me.uk>
> wrote:
>
>> On Sun, 2017-12-10 at 18:25 +0000, Nick Bolten wrote:
>>
>> The downside of using `wheelchair=no` is that there are many conditions
>> that will prevent some, but not all, wheelchair users from using the
>> infrastructure. For example: some wheelchair users don't care about curb
>> ramp info at all because they're comfortable finding driveways and going in
>> the street (`kerb=raised` does not imply `wheelchair=no`), while others
>> absolutely require proper infrastructure (most powered wheelchair users,
>> `kerb=raised` implies `wheelchair=no`). I recommend tagging specific,
>> on-the-ground conditions that can be interpreted later, like `kerb`,
>> `barrier`, `width`, `surface`.
>>
>> Another thing is that you probably want this info to be immediately
>> useful, but I'm not aware of any existing routers that can use sidewalk=*
>> subtags, as the sidewalk=* on a street model has to be expanded to a new
>> graph (and the vast majority of routers don't do that). OpenTripPlanner is
>> attempting to develop this, but it's unreleased. That doesn't mean you
>> shouldn't tag, but it's a segue for my next recommendation: consider
>> mapping sidewalks as separate footways. More or less, you describe
>> sidewalks as `highway=footway` `footway=sidewalk`, connect them via
>> `highway=footway` `footway=crossing` ways, and ensure that those crossings
>> intersect and share a node with streets.  While this involves more ways, it
>> makes it much easier to organize and use the kinds of subtags you're
>> interested in using, and can be used directly in most routers. For example,
>> you wouldn't have to make an executive decision about `sidewalk:width` vs
>> `width:sidewalk` - just use the widely-documented `width` tag.
>>
>>
>>
>> Mapping as separate ways can cause many issues, the basic rendering issue
>> where streets already collide with buildings, plus where do I put the
>> crossings other than make them up?
>>
>> A pedestrian can cross the road anywhere and will not want a route that
>> does not allow that most basic of concepts.
>>
>> Phil (trigpoint)
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