[Tagging] Formally informal sidewalks

marc marc marc_marc_irc at hotmail.com
Sat Jul 15 11:13:27 UTC 2017


Le 15. 07. 17 à 12:04, Svavar Kjarrval a écrit :

> This point is demonstrated in my quoted example [2]. 
> Mapzen assumes the user can jump over the road
>  (or assume the user is already there) and walk a few steps, 
Your demonstration is only that a wrong map create sometimes a wrong 
routing :-)
What will your reaction be when Mapzen tell you to cross a road where it 
is impossible ? However this is exactly the current map for [2]
You would not agree that the routing would make you drive from one road 
to another because they are close and it save 1km. Therefore I do not 
understand why you would want the routing to do this when you are walking.
If the map is wrong, first fix the map, not the routing engine.

> but GraphHopper directs the user to take a complicated path
Complicated because the map is wrong in this case.
GraphHopper will not make you cross a road where a mapper tell 
(unintentionally but erroneously) it is impossible.
Is it bad? IMHO no, it is the best reply.
I think that is the problem. You would like the routing to guess errors 
and guess where we can jump from one path to the other in the absence of 
connection.
But the simplest/efficient/only solution is to fix the map.

>>> where the footway ends prematurely, the routing software
>>>  doesn't know it may suggest such a "jump" onto the street or not,
>> the end of the footway must be connected to the street if you are
>> able/allowed to switch to the street by foot.
>> If needed, cut the road : one segment with sidewalk=left/righ, second
>> segment with sidewalk=no
> Just to be clear: Is it valid, in your opinion, to connect the end of a
> footway along a street, directly to the street itself?
> I'm not objecting to such a method, I've just been hesitant to apply it
> without approval by documentation or the community.
Guidelines for roads is very easy: split a road in 2 when you can NOT 
switch from one to the other (for example a road with a island). and 
create connection where you can switch. But do NOT cut a road into 2 if 
you switch everywhere from one to the other (for example a street with 2 
lanes must be keep as one street, not 2).
Just do the same with the sidewalk as if the sidewalk was a lane 
reserved for pedestrians. I never see a problem with that.

> [2] A link with navigation routing:
> http://www.openstreetmap.org/directions?engine=mapzen_foot&route=64.08769%2C-21.90140%3B64.08802%2C-21.90113#map=19/64.08791/-21.90122

Regards,
Marc


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