[Tagging] How to tag: Legally separated ways

Colin Smale colin.smale at xs4all.nl
Mon Oct 15 18:08:01 GMT 2012

I don't understand why emergency vehicles are so important in this 
discussion. In the first place they have wide-ranging exemptions from 
traffic rules, which (let's be honest) we are never going to tag in OSM. 
Secondly they are never going to be relying on OSM data (or indeed any 
normal sat-nav) for lane-precise routing. They are trained to use their 
eyes and brains to make split-second decisions on what is safe and an 
acceptable risk under the circumstances of that moment. Thirdly, they 
will be about 0.0000000001% of the potential users of OSM data - why 
should we compromise "service" to the vast majority of real users for 
the hypothetical benefit of the very few.


On 15/10/2012 19:55, Alberto wrote:
>>> a) One way with lanes=4
>>> b) Two separate ways with lanes=2 each
>>> c) Tell me!
> a) because distinction between physical and legal barriers is important.
> Ok in that picture there is no much difference, but as Simone pointed out,
> for long roads there is a big difference: if any router can't distinguish
> between physical and legal barrier, it will not suggest to emergency vehicle
> to cross the line, and it will tell them to do a long alternative trip
> instead. This is a big problem, because when you are driving the GPS shows
> you only a little portion of the route and you may not understand
> (especially in emergency) that you can shorten the route simply crossing the
> line.
> Moreover if we accept solution b) we should tag every road with continuous
> line in the middle as two separate roads, one for each direction.
>> Additionally to the lanes=4 and oneway=yes you could put a divider-tag on
> the way http://wiki.openstreetmap.org/wiki/Proposed_features/Divider
>> even if it doesn't explicitly tell you where the divider is placed you
> might be able to infer it from the following ways (at least in this case).
> +1 We can improve this proposal, to make clear where the divider is placed.
> Cheers
> Alberto (Viking81)
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