[Tagging] Positioning motorway exits

[Johan C]

Well, the WIKI more or less has a sort of consensus. Yes, we do have the
divided highways ('baulicher trennung'). But there is also the consensus
that it's important to make sure the requirements for navigational devices
like OSMAND should also be met. So, if the physical point is used by a
mapper some extra tagging is needed to show the legal point for the exit.
And the routers should then be altered to handle the extra tagging. OSM is
no toyland anymore, people (like myself) are more and more relying
on reliable OSM data for navigational purposes.

An example for Belgium shows the motorway_junction node way too early:
https://www.openstreetmap.org/?mlat=50.86948&mlon=4.48244#map=18/50.86948/4.48244&layers=N
But that's safer for driving than having it too late.

Cheers, Johan


2017-03-07 15:45 GMT+01:00 Jo <winfixit at gmail.com>:

> Extra credit if we can come up with a 'universal' solution :-)
>
> Polyglot
>
> 2017-03-07 10:44 GMT+01:00 Volker Schmidt <voschix at gmail.com>:
>
>> This touches on a "conflict of interest" between two requirements:
>> (1) OSM tagging practice is to map only physically separated ways as
>> separate ways in OSM.
>> (2) A routing algorithm needs to have information about legally separated
>> ways, e.g. by a continuous white line.
>>
>> In the specific case the exit for the routing algorithm is at the
>> beginning of the continuous white line, i.e node
>> https://www.openstreetmap.org/node/4337339247
>> whereas the split of the ways according to the rule of the separate ways
>> puts it at node https://www.openstreetmap.org/node/370544/, where the
>> motorway junction is placed at the moment.
>>
>> To my knowledge there is no agreed upon common practice.
>>
>> I do not map motorways in Germany, but have mapped motorways and trunk
>> roads in Italy where we have no established common approach, and you can
>> find a nice mix of different approaches. I think we should come to a
>> general best-practice or best-practices agreement. This may imply
>> country-dependent recommendations.
>>
>>
>>
>>
>>
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