[Tagging] highway=footway - Advanced definition: Distinction footway vs path
gdt at ir.bbn.com
Wed Aug 5 23:33:46 UTC 2015
Martin Koppenhoefer <dieterdreist at gmail.com> writes:
>> Then what is the point of having path and all these other tags that overlap?
> because path and bicycle=designated is the same as highway =cycleway
> path with horse=designated is the same as highway =bridleway
> and you can also make combinations without having to decide for
> footway, cycleway or bridleway. Also, without any further access tags,
> path is neutral and open to all unmotorized means of transport (unlike
> footway, cycleway etc.)
I agree with what Martin said. I also agree with previous commenters
that redefining semantics of path or adding footpath would cause a lot
of problems. A few problems and random comments.
There's no clear default for path, footway or every cycleway about
surface. The obvious answer is that surface tags should be used.
Similarly, a width tag should be used. Or perhaps some tag that
indicates a forest trail. But this shoudl be extra, so that data
consumers that don't know about it will still know that
foot/bike/etc. traffic works.
There is talk about access and emergency. An emergency 4-wheel
vehicle might or might not be allowed (and needs an explicit yes tag,
as vehicle types default to no on all of these), but it will not
physically fit. If it did fit, the way should be tagged as a track.
The default rendering is problematic in two ways;
path is much heavier than footway/cycleway/bridleway, which are
similar except for color. A path is really just a way that is a
footway, cycleway and bridleway all at once, and thus is not a
larger or more significant way. So the rendering should not have
more visual weight. Arguably the colors could alternate among the
allowed ways, if there is no designated. And of course bike renders
would just key off bicycle=yes, mostly.
A track marked as no access for regular cars and yes for foot should
probably render, in the default render, as something more like a
footway. Or at least something less than track. This is because
from the car viewpoint, it might be possible but it's not allowed.
From the foot viewpoint, it's just a wide path.
I believe that a lot of the footway/path angst would go away if path
stopped looking like a higher class of road.
For all of these, some notion of hierarchy is needed. For roads, we
have primary/secondary/etc., which has its own issues. For footways
as an example, we have sidewalks that are not particularly interesting
except at high zoom levels. But a foot path that goes 3 km through a
forest is interesting when you can see the whole forest, just like a
through road. This is not easily determinable automatically, because
the 10 km through path that junctions with a sidewalk does not make
the sidewalk important. Importance is determined by the way being
useful for a long hiking route. So probably some sort of importance
tag is needed. One approach would be a tag distance=X, where X is a
distance that one could reasonably travel where that way would be
naturally a component. Perhaps X should be rounded to 1/2/5 x 10^k m.
I don't really like this suggestion, but I think we need something
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