[Tagging] Proper way to tag highways located in "dangerous" areas

joost schouppe joost.schouppe at gmail.com
Wed Nov 16 11:08:56 UTC 2016

Absolutely agree that access=destination is wrong here.

I also like the idea of using an external dataset. Actually, the similarity
with an altitude model is quite interesting. You could use an existing
router that takes elevation data and replace it with crime data. Converting
crime statistics to something that looks like an altitude model is
straightforward with a GIS tool. Or someone could make a website (probably
exist already) to collect opinions on security by neighborhood, then
convert to an altitude model. Crime being quite concentrated (in my city
80% of all registered violent crime is concentrated in just 16% of the
city), a router wouldn't have much trouble avoiding the higher places.

2016-11-16 11:36 GMT+01:00 Rory McCann <rory at technomancy.org>:

> I don't think tagging access=destination is a good idea. The access tag
> is used for the legal restrictions for a road. access=destination means
> you can only legally go on the road if your destination is on it. A
> router won't route you down a road that it thinks you (legally) can't go
> down. Tagging that way will stop the router routing you on it, but for
> the wrong reason. You're "tagging for the router".
> Many countries use access=destination to mean this, I suppose the
> Brazilian community could use the tag in a different way, but it'd
> usually better for us all to use the same tag/values. 🙂
> There are some possible solutions to your problem:
> Are slums/flavelas (sp?) tagged/mapped in OSM? If so, a router may be
> able to downgrade roads that are near a slum by looking at what's nearby.
> Do the roads in slums have any common physical properties? Like always
> being narrow, with no footpaths, lower speed limits, etc? You could map
> those attributes, and a router might be able take them into account. (A
> narrow road with pedestrians walking on it, and a low speed limit might
> be downgraded compared to a more straighter, easier-to-drive road).
> The idea of using an external dataset to inform routing isn't new. Some
> bicycle routers use external elevation data to not route people up and
> then down a hill. Perhaps there's a dataset of crime/damgerous areas you
> could combine with OSM data to make a better router.
> However I don't know if any/many routers currently support this kind of
> features. So people might just want to keep using the routers they have
> and "fix" them.
> On 16/11/16 02:04, Nelson A. de Oliveira wrote:
> > It's the second time that we are having a major discussion here in
> > Brazil, on how to tag highways located in "dangerous" areas.
> > For example, some people consider slums and other communities as
> > dangerous (since there is a risk of being robbed or even killed) and
> > would like to don't have the router creating a route through them,
> > using "access=destination" in every street located in such places for
> > this, for example.
> >
> > Since they can't find another tag to indicate those "dangerous"
> > places, they argue that access=destination is valid for this case.
> >
> > Other group (including me) find that this is wrong: we should not tag
> > streets considered dangerous in OSM (specially when "dangerous" is
> > subjective).
> > We also think that access=destination is being wrongly used for this.
> >
> > Since we can't reach a consensus on this, we would like to hear some
> > opinions and suggestions on how to handle such problem, please.
> >
> > I had one idea where such data should be kept outside OSM, and
> > inserted in some post-processing phase (for example, tag every highway
> > that is inside these areas with any needed/wanted property).
> >
> > Comments, please?
> >
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