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

Sun Mar 23 10:12:36 GMT 2014

On Sun, Mar 23, 2014 at 09:52:53AM +0100, Gerd Petermann wrote:
>I am not sure how I should interpret a restriction relation with 
>restriction=only_* and a via way.  AFAIK the Garmin format doesn't have 
>such kind of restriction, so we have to translate it into one or more 
>no_* restrictions for the other possible ways. This was rather easy for 
>restrictions with a via node, but how should I do it for via ways?
>Examples:
>http://www.openstreetmap.org/relation/67571

This looks like a mapping error (should simply use a 'via' node).

>http://www.openstreetmap.org/relation/1745548

This one is more tricky.

The note on the relation says that there is a lane marking that you 
cannot cross when turning right from the parking lot. So, you can only 
continue straight to Mäkelänkatu and not take an immediate left turn to 
Vääksyntie.

It seems that also this one could be corrected in the map data by 
branching the Vääksyntie exit before the parking lot driveway. In that 
case, there would be no need for a turn restriction.

The real trouble (AFAICT) is no_u_turn with role=via ways. That cannot 
be fixed by manually simplifying the map data.

	Marko