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[mkgmap-dev] Turn restrictions with role=via ways

From Marko Mäkelä marko.makela at iki.fi on Thu Mar 13 22:03:43 GMT 2014

Now, with all these routing improvements, I wonder if it would be 
possible to extend our support for turn restrictions.

Some mapper seems to prefer via ways to via nodes in this crossing:


This 2-node way is a role=via member of a no_u_turn restriction that has 
4 ways as members: from,via,via,to. It is also a role=via member of a 
no_left_turn restriction.

The no_u_turn restriction could have been mapped with three ways as 
from,via,to and the no_left_turn could have been mapped with having this 
way as role=from, and a node as role=via. Even if I changed the map like 
that, mkgmap would still ignore the no_u_turn, because the role=via 
member would be a way.

So, I wonder if we could start supporting this style of mapping? There 
are lots of dual carriageways in city areas where such turn restrictions 
are common, at least for no_u_turn.


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