[Tagging] "width" on streets: Time for a recommendation

[Tobias Zwick]

>To me it seems obvious that width values, independently on how they are
>measured, are at best estimates, as measuring them is in most cases
>dangerous or requires good technical equipment. 

I don't think this is true anymore. Did you try out "Measure" or any other ARCore/ARKit-based measuring app? Example:

https://m.youtube.com/watch?v=qz0YJ0s4JLM

Am 20. September 2020 00:01:00 MESZ schrieb Volker Schmidt <voschix at gmail.com>:
>Some thoughts that trouble me...
>
>To me it seems obvious that width values, independently on how they are
>measured, are at best estimates, as measuring them is in most cases
>dangerous or requires good technical equipment. I guess that most width
>values in the database are reality estimates (I don't think that this
>is an
>unjustified extrapolation from my own mapping - 99.9% of my width
>tagging
>based on estimates). Estimates are relatively easy for narrow roads if
>you
>have street-level photographs. They become much more unreliable for
>wider
>roads. I solve this by using only lanes count for wider roads. Precise
>width measurements are difficult to impossible, but fortunately they
>are
>also less important than the lanes count for the end user.
>
>The discussion about including/excluding sidepaths/sidewalks becomes
>also
>irrelevant if we were only to use the lanes count as that counts only
>motor
>traffic lanes.
>
>Would also overcome another aspect of the width definition: If we use
>width
>for the entire road, i.e motor-traffic lanes, shoulders, sidewalks,
>cycle
>lanes/tracks/paths, tree rows between foot and cycleway, ... we do in
>the
>end not know enough about the the actual widths of the different
>component
>"lanes".
>
>Width values are useful and easy to estimate from street-level
>photographs
>for sidewalks, cycle paths/lanes/tracks, certainly to within 0.5m
>precision.
>
>We need in any case a good system for regrouping parallel ways that
>belong
>to the same street.
>A relation seems to me the better option, but in any case, whatever
>approach we pick now, we will face an nearly impossible amount of
>retrofitting work. Anything we do on this from now will not make the
>problem go away with the existing stock of data.
>
>Volker
>
>
>
>
>
>
>
>
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>On Fri, 18 Sep 2020 at 22:35, Tobias Knerr <osm at tobias-knerr.de> wrote:
>
>> On 17.09.20 02:35, Taskar Center wrote:
>> > This is yet another example why "sticking" the sidewalks onto the
>> > highway (as a tag) rather than mapping them as separate ways is
>> > appearing to be less and less practical. Please see our sidewalk
>schema
>> > proposal
>> >
><https://wiki.openstreetmap.org/wiki/Proposed_features/sidewalk_schema>
>> > from several years ago.
>>
>> Your sidewalk proposal unfortunately doesn't really address the
>crucial
>> shortcoming of separately mapped sidewalks: The lack of a reliable
>> mechanism for figuring out which section of road a given sidewalk way
>> belongs to.
>>
>> I agree that we should be able to give sidewalks their own geometry,
>but
>> we _also_ need the relationship between sidewalk and road. So far,
>all
>> the proposals attempting to support the former end up sacrificing the
>> latter.
>>
>> There have been some promising discussions recently around the
>> sidepath_of idea, but that's still just brainstorming. Until a
>practical
>> solution is found and actually used in the database, sidewalk mapping
>> will remain a choice between two options that are broken in different
>ways.
>>
>> As for the main issue of the thread: I would welcome a clear
>definition
>> for the meaning of width. In my own mapping and when writing the
>> relevant code in OSM2World, I have counted sidewalks etc. as part of
>the
>> road's width if they are mapped as tags on the main way. But I would
>of
>> course change that if there finally was a documented and widely
>> agreed-upon recommendation. I don't care so much which one it is -
>but
>> we need one.
>>
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