[Tagging] Reviving the path discussion - the increasing importance of trails in OSM

[Andrew Harvey]

On Mon, 25 May 2020 at 11:54, Kevin Kenny <kevin.b.kenny at gmail.com> wrote:

> On Sun, May 24, 2020 at 8:01 PM John Willis via Tagging
> <tagging at openstreetmap.org> wrote:
> > Mapping “where the sidewalk ends” and the trails begin is vital to keep
> people from being routes where grandma could have a heart attack Climbing a
> difficult route or break her leg crossing a stream because we routed her on
> a trail down a ravine rather than on the longer, yet safer sidewalks down
> along the roads or paths through a local park because there is no way to
> say “THIS IS A TRAIL, not a walkway through a playground” in OSM.
>
> We do have that: `sac_scale=hiking`; as I understand it, few trails go
> beyond 'hiking', so that's at least better than nothing. (It still may
> suffer from underestimating the trail, leading city folk to the
> sketchy rock scrambles when they're expecting a nice level dirt path,
> so try to get the scale at least reasonable.)
>
> What we don't have - at all - is the complement: 'THIS IS INDEED A
> PATH'.  When we see 'highway=path', we don't know whether it's indeed
> a path, or a hiking trail where the mapper didn't assign an
> `sac_scale`.  We need a way to assert 'THIS IS A PATH' that doesn't
> depend on the absence of a trolltag.
>
> I can't stress enough that as long as we have the ambiguity, the only
> way to 'fail soft' is to support the assertion 'this is relatively
> safe', because we can deduce nothing from the absence of a 'this is
> dangerous' assertion.
>
> Incomplete information should 'fail soft'.
>
> On Sun, May 24, 2020 at 8:32 PM Andrew Harvey <andrew.harvey4 at gmail.com>
> wrote:
>
> > Agreed, the biggest question is how do you define that criteria for what
> is going to be tagged a a hiking trail and not a hiking trail.
> >
> > Eg. if you have a smooth paved track through the rainforest that the
> authorities created for grandparents and strollers, is that a hiking trail
> just because it's in a forest area? What about a stroll through the hills
> of grasslands that have no forest or mountains, is that marked as a hiking
> trail?
>
> No, just being in a forest doesn't make something a trail.  I think
> that it's pretty safe to assume that 'surface=compacted
> smoothness=intermediate wheelchair=yes` with a connection to a highway
> or parking area not strictly a hiking trail, and there are some trails
> near me- even in Wild Forest areas- that are constructed in such a way
> to offer wildland access to persons with disabilities. I'd be happy
> considering those trails on an equal footing with urban paths.
>
> A hiking trail can be an easy trail through the lowlands. (Those are
> rare near me, because the lowlands are mostly either settled and
> subdivided, or else sucking swamp, so the mountains are what is left
> for hiking trails to go.) I already mentioned that sac_scale discounts
> hazards other than mountains (and focused on water, but Graeme can
> surely fill in a number of deadlies that are specific to his
> continent).
>
> A lot of it comes down to, "would you route mobility-impaired people
> or folks with small children in tow down this?"  A wrong decision for
> some ambiguous corner case will be mostly harmless. Not having the
> information for a dangerous trail might be deadly.
>

Yeah right now you can use sac_scale=hiking, but I agree we are lacking a
tag to say this is not considered hiking.


>
> > I think it's too hard to have a reliable criteria for this which can be
> objectively surveyed, it's much easier to tag each attribute individually
> on their own independent scale.
>
> The _reductio ad absurdum_: by the same token, because there is
> controversy in many locales over which highways should be
> `highway=trunk` and which should be `highway=primary`, or which should
> be `highway=service` and which should be `highway=track`, all highways
> should be tagged just `highway=road` and the relevant attributes
> (surface, smoothness, speed limit, number of lanes, ...) should be
> mapped instead. Few if any of us think that would be appropriate. Why
> can cars get a hierarchy of ways, while hikers, equestrians and
> cyclists cannot?
>

If you can come up with a proposal I'd love to see it, of course I want to
see it happen to, but I just can't see what the hierarchy should be. For
roads the hierarchy is based on importance of the road in the road network
(eg is it a major connection between cities or just a road used to access a
drive through car wash). Things like surface, smoothness etc don't affect
the road hierarchy. So how would you decide a hierarchy for hiking trails?
How popular the track is? How well built the track is? How technical is the
track? How physically difficult is the track? How well signposted is the
track? How remote is the track?
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