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#1 2020-08-21 13:50:12

Heinz_V
Member
Registered: 2009-02-23
Posts: 177

NH mapping changes

Actual situation:
1) each NH has a relation for the whole trunk including the ways in both directions
see : https://wiki.openstreetmap.org/wiki/Ind … numbering)
2) these relations have a tag „network=IN:NH“
3) each NH has seperate relations for each state; included are the ways in only one direction. NH ways, which are shared by 2 or 3 Nhs have a seperate relation for these parts. With these relations it is possible to calculate the exact length of the Nhs in whole India and in each state. These relations have a tag like „network=IN:NH:KL“ to indicate the state.
See for example : https://wiki.openstreetmap.org/wiki/Kerala-NH

Disadvantage of this mapping:
1) quite complicated
2) a lot of errors occur, because new mappers do not know the construction rules as described above

Advantage
1) exact calculation of length
2) easy download of all Nhs in Kerala...

I want to propose now a different mapping of all Nhs, so that the additional relations are no longer needed:

1) the relations in https://wiki.openstreetmap.org/wiki/Ind … numbering): all members are to be updated with „role=forward“ or „role=backward“. I would use forward for south and east. Important is, that this choice is unique for the whole NH.
2) all additional relations (only one direction and for each state) shall be deleted
3) wiki-pages for the states: here we use the ID number of the whole NH-relations and the correct length in the state
4)  the length calculation for India/single state/ district../single NH can be done by a overpass turbo query using the role-values. These queries should be defined and added to the wiki state-pages.
5) Also the download of single Nhs/ Nhs in a single state/… can be done by overpass turbo queries.
6) Of course we still need correct mapping, but it is a bit easier.

If you agree to this mapping changes, I could start with a single state.

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#2 2020-08-22 03:00:07

PlaneMad
Member
Registered: 2008-09-16
Posts: 29

Re: NH mapping changes

Fully support having only one relation per NH for ease of maintenance.

I'm not seeing any downside to losing the mentioned advantages as they are very special uses and they could be accomplished by other ways as long as the core NH relation is not broken.

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#3 2020-08-22 07:35:01

Srihari Thalla
Member
From: Hyderabad, Telangana, India
Registered: 2016-11-23
Posts: 20

Re: NH mapping changes

Looks good!

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#4 2020-08-22 09:56:15

Heinz_V
Member
Registered: 2009-02-23
Posts: 177

Re: NH mapping changes

I am not sure that my proposal is optimal.

With the single relations for a whole trunk we have created some monster-relations.
NH44 : 4746 members
NH27 : 3138 members
NH48 : 3067 members ...
The relation analyzer can no longer handle NH44 and NH27.

How are tunks/motorways mapped in other countries?
1) China : monster-relations with more than 7000 members (Shanghai to Istambul); unpossible to maintain
2) France, Germany… : for a single trunk/motorway several relations for each departement..; these relations are combined in a superroute relation, to define the whole highway.

I think, it is important to have the possibility to control the relations. Too often Newbies delete parts and remap these parts,but do not update the relations.  With the relation analyzer it is easy to find these holes.

A solution could be :
we create for each NH a relation for each state seperately; then we combine these relations in a superroute-relation for the whole NH with „network=IN:NH“. It is not so easy to Newbies to damage superroute relations. 
For superroute relations see: https://wiki.openstreetmap.org/wiki/Relation:superroute
The relation of a NH in a single state could have for example „network=IN:NH:KL“ to define the state. So it is quite easy to download this in an overpass query.

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#5 2020-08-22 10:27:32

Srihari Thalla
Member
From: Hyderabad, Telangana, India
Registered: 2016-11-23
Posts: 20

Re: NH mapping changes

That would mean rolling back, isn't it?

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#6 2020-08-22 10:38:32

Heinz_V
Member
Registered: 2009-02-23
Posts: 177

Re: NH mapping changes

No, with my proposal in post 1 and 4 :
each way of an NH would be only in one normal relation (as PlaneMad prefers). This relation combines all ways of the NH in a single state. And these relations of the states are members of a superroute relations.

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#7 2020-08-23 02:45:14

PlaneMad
Member
Registered: 2008-09-16
Posts: 29

Re: NH mapping changes

> This relation combines all ways of the NH in a single state. And these relations of the states are members of a superroute relations.

Using a superroute relation sounds like the most logical solution.

I'm curious what effect this has on the Wikipedia/Wikidata dynamic map query like the generation of the map in https://en.wikipedia.org/wiki/National_ … 44_(India) . Would it still be possible to generate such maps in Wikipedia with the relation restructuring?

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#8 2020-08-23 06:38:59

Heinz_V
Member
Registered: 2009-02-23
Posts: 177

Re: NH mapping changes

These wikipedia maps are possible with splitted relations and superroute relation.
See : https://en.wikipedia.org/wiki/Bundesautobahn_1
This is a highway with two relations (north part till border Niedersachsen/NRW) and the rest. Additional a superroute relation.

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#9 2020-08-23 06:42:33

Heinz_V
Member
Registered: 2009-02-23
Posts: 177

Re: NH mapping changes

Oh zooming in the NH44 wikipedia map near Dehli : You see, that wikipedia do not use the OSM relations but paint the NH in an additional layer!:lol:

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#10 2020-08-24 22:13:58

Heinz_V
Member
Registered: 2009-02-23
Posts: 177

Re: NH mapping changes

I controlled a lot of NH and found really many errors. My conclusion: It is important to change the mapping system; better as simple as possible.
That means :
- one relation for each NH in each state
- an additional superroute relation, if the NH passes throw more than one state
- no use of forward/bachward, since this has not the proposed meaning.

For measuring the distances I do no longer need something like forward/backward.

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