[Tagging] surface=gravel problems

Bert -Araali- Van Opstal bert.araali.afritastic at gmail.com
Tue Apr 27 21:54:36 UTC 2021

On 27/04/2021 23:41, Martin Koppenhoefer wrote:
> Am Di., 27. Apr. 2021 um 22:01 Uhr schrieb Bert -Araali- Van Opstal 
> <bert.araali.afritastic at gmail.com 
> <mailto:bert.araali.afritastic at gmail.com>>:
>     If you mean the keys winter_road and/or ice_road, I find those
>     hardly helpfull to describe the road conditions and how feasible
>     it is to use these for different road users.
>     To some extend an attempt was made to resolve the issue with
>     tracktype, like in AUstralia and 4WD drive tagging. However these
>     refer to vehicle types to describe how they can be used, doesn't
>     give any information what the hazards or conditions are.  SO I
>     don't find these much informative to make any conclusions in that
>     regard either as in Africa most of us are very skilled unpaved
>     road drivers, even without 4WD vehicles.  It doesn't give you a
>     clue how it is to use these roads by bicycle, on foot, wheel
>     carriage, normal car, truck etc...
> do you believe there is a way to integrate this kind of information in 
> the current tagging scheme, and how would you do it?
We have been struggling with this like forever.

The direction I am thinking about is something (very preliminary) like this:


hazard:TYPE:CONDITION= none / mild / substantial / severe

where TYPE gives the type of hazard. TYPE being dust / slippery / 
traction / washboarding(skidding) / noise / holes / mudsink / sticky / 
mudsplash / wildlife / flooding / spray / thrown-up stones / overgrowth 
/ dust dunes / fog / icing / snowpiles.
I am thinking about a hazard key because like f.i. the dust is not only 
a hazard for the road user but also for the environment and residents 
close to the road, and can be very severe. So data consumers can use the 
tag on the road also to analyse possible environmental and health impact 
on the surroundings.
What I don't like in this concept is that we use multiple "values" in 
the key, but didn't come up with a more simple solution yet.
CONDITION is like wet / dry / freezing.  I don't like to use the 
seasonal key here, as it is also not conclusive as f.i. to describe 
freezing conditions or not, wet and dry as in wet and dry seasons as due 
to our changing seasons and varying seasons (especially wet / dry) on a 
regional basis.

What this model lacks is a time constraint for daily variations, like 
for instance the fog hazard might be only common in the morning or 
evening hours.
The frequency of different vehicle or road users which can influence the 
hazards impact.  F.i. one could use frequency tagging like for motorised 
vehicles which makes the dust or noise hazard much more severe, but a 
high frequency of bicycle or pedestrians would not.  Also this makes the 
whole range of data more complex but is needed to be conclusive.


An alternative could be to classify the hazards in regard to road users.
Like: hazard:pedestrian:wet=mudsink; slippery.
The problem with such a scheme is that it becomes complex when you want 
to integrate the severity of the hazard.


One could think about hazard:pedestrian:wet= mudsink severe; slippery 
mild etc... but this introduces values with multiple conclusive data in 
one value.


An alternative to that could be to just give a general indication like 
hazard:pedestrian:wet= mild.  Needing another tag to indicate what the 
actual hazard is, as f.i. it can be mitigated by proper measures like 
wearing a mask for dust...

Very happy to get some ideas about this.

As you can see I can make no conclusions from the current tagging with 
surface, smoothness, tracktype or seasonal tagging yet I can imagine 
these road use conditions can be of ajor importance and decisive for 
routing purposes, for various road user categories.

>>>     All efforts which we use today for smoothness and surface is just short term, non-conditional information
>>     the smoothness tag is clearly coming from an area where paved road surfaces are predominant (you can see this from the definition and distribution of values). If it doesn’t work well for unpaved roads, that’s not a reason to deprecate it for everybody.
>     I didn't say we should deprecate it, but I think we can agree on
>     the fact that, besides that it maybe says that are are potholes it
>     doesn't give you much information or conclusive ways to describe
>     suitability or comfort for different road user categories ?
> I am not using it a lot, but I think it is suitable to say a road is 
> smooth and suitable for any vehicle,  but it may be less on par for 
> describing relatively bad surfaces. The smoothness tag was introduced 
> by a Swiss mapper, and most of our tags are developed in Europe. You 
> are the first person from Africa who participates frequently on this 
> list, and I truly welcome this. We really need more input and 
> proposals from different regions.
It's not just a topic in Africa, I do believe many countries in Asia, 
Australia and South America face the same issues and we really need some 
more participation from those areas also.

I also think in the Western countries, on paved roads many of these 
hazards can be decisive for routing choices.  Spray, icing, fog .... may 
be signposted but also may be not.  Besides of traffic_signs OSM lacks 
tagging and data to provide this information, yet is easily to be 
obtained by ground truth and has a high impact on our daily lives.

Maybe we need an international volunteer team to work on a comprehensive 
global yet KISS proposal ?


Bert Araali

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