[Tagging] River crossing grade

[Philip Barnes]

On Wed, 2022-01-26 at 18:13 +0000, Timothy Noname wrote:
> I think it's far more likely we can clarify existing "fords" with a
> new tag than get everyone to change the existing fords. 
> 
> A data used who sees a fords without a grading will know that it is
> vague and may not even be a real ford. If the grade is present they
> know exactly what it is.
> If we introduce a new tag for "fords" that aren't real fords, eg
> crossing=stepping_stones, data users will never know whether ford=yes
> is a real ford or not.
> 
> Something also needs to be done for cars, I know fords that are
> passable by any car at low tide and some that are only passable by
> large 4x4s. This could be inferred from the depth of the ford and the
> surface of the road but IMO would be better tagged explicitly.

Tidal is certainly an unusual thing for a ford, I have seen one or two
but most roads affected tides are causways and the general rul is you
do not travel on them if they are covered with water. Tide implies salt
and I would certainly not drive one no matter how shallow the water is.

Most fords are on rivers or streams and the depth will be variable
based on recent rainfall withing the watershed, some may be impassible
after heavy rain and you do need to be aware of the weather over the
past few days. 

Fords on public roads generally have a depth guage which allow a driver
to check if crossing is sensible. Many on public roads also have a
footbridge.

Phil (trigpoint)


> 
> On Wed, 26 Jan 2022, 17:13 Zeke Farwell, <ezekielf at gmail.com> wrote:
> > A ford is a shallow place in a waterway where one can wade or drive
> > through the water.  You will get wet at a ford.  It's not really a
> > ford if the stream is so narrow that you can jump across, or so
> > shallow that you can walk on stones above the water and your feet
> > barely get wet.  It's also not really a ford if the water is so
> > deep that your feet can't touch the bottom and you have to swim
> > across.
> > 
> > The osm key "ford" seems to be taking on a wider meaning than the
> > English word "ford".  ford=stepping_stones describes something that
> > I would not consider a ford.  The wiki also documents ford=boat
> > which sounds very strange to me as a native English speaker.  A
> > ford is a place where you specifically do not use a boat.  If a
> > boat is used, that is called a ferry.
> > 
> > Rather than overloading the ford key, I suggest we create different
> > tags for very narrow/shallow crossing places, and minor ferry boat
> > crossing.  Neither of these are really fords.  If this is done I
> > think there is much less need for a crossing grade scale.
> > 
> > 
> > On Wed, Jan 26, 2022 at 11:51 AM Volker Schmidt <voschix at gmail.com>
> > wrote:
> > > Please do not introduce another grade scale - already enough
> > > trouble with track grades.
> > > 
> > > Some immediate problems:
> > > 
> > > a river crossing where your body normally gets wet or you have to
> > > swim or to take a boat is not a ford.
> > > (The wiki page key=ford shows as option ford=boat)
> > > 
> > > 
> > > 
> > > 
> > >    Virus-free. www.avast.com
> > > 
> > > On Wed, 26 Jan 2022 at 16:03, Timothy Noname <hervbeof at gmail.com>
> > > wrote:
> > > > I think depth and width are too difficult for the average
> > > > mapper to determine and would be difficult for users to
> > > > interpret.
> > > > 
> > > > I agree that some sort of tag is needed to describe the ease of
> > > > crossing. 
> > > > I see fords on OSM footpaths all the time and have no idea if
> > > > they are a potential obstacle or not. Most of them are very
> > > > easy to just step over, some require waterproof boots, some the
> > > > water might come up to your knees. Some are also tidal and the
> > > > variance is huge.
> > > > 
> > > > 
> > > > I would suggest some possible values:
> > > > step_over, very_shallow (trainers ok), shallow (waterproof
> > > > boots needed), wade, swim, difficult_swim
> > > > 
> > > > Tag name something like 
> > > > foot_crossing_grade
> > > > foot_crossing_grade:min
> > > > foot_crossing_grade:max
> > > > 
> > > > 
> > > > On Wed, 26 Jan 2022, 11:29 Martin Koppenhoefer,
> > > > <dieterdreist at gmail.com> wrote:
> > > > > 
> > > > > 
> > > > > Am Mi., 26. Jan. 2022 um 12:21 Uhr schrieb John Sturdy
> > > > > <jcg.sturdy at gmail.com>:
> > > > > > And if we do want to repeat that (and I agree with Mateusz,
> > > > > > that we probably shouldn't) we should probably make it 1--5
> > > > > > rather than 0--4, for consistency.
> > > > > > 
> > > > > > How about giving the typical depth of the crossing in
> > > > > > metres?
> > > > > > 
> > > > > 
> > > > > 
> > > > > 
> > > > > "depth" is used together with "ford":
> > > > > https://taginfo.openstreetmap.org/keys/ford#combinations
> > > > > 
> > > > > Cheers,
> > > > > Martin
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