[mkgmap-dev] r3165 in via_ways branch

Sat Apr 5 17:48:49 BST 2014

Hi Marko,
> Thanks, this message is no longer being issued for this relation.
> 
> Here is another:
> 
> 2014/04/05 18:38:10 WARNING (RoadNetwork): 63240002.osm.pbf: Turn 
> restriction (only_right_turn) 
> http://www.openstreetmap.org/browse/relation/423035 (at 
> http://www.openstreetmap.org/?mlat=60.168471&mlon=24.934714&zoom=17) 
> restriction ignored because all possible other ways are wrong direction 
> in oneway
> 
> The way straight ahead is marked as oneway=yes that prohibits entry, but 
> it carries bicycle:oneway=no, psv:oneway=no. Similarly, the turn 
> restriction is tagged as except=psv;bicycle.
> 
> While it is a redundant restriction, I suspect that this form of tagging 
> is not being recognized by the via_ways branch. Would mkgmap now be 
> refusing bicycle routing straight ahead? At least the message is a bit 
> misleading or imprecise. I understand that the ; delimiter is 
> troublesome. How should this be tagged? restriction:bicycle=no?

For mkgmap, the except tag can contain a comma or semicolon separated list.
On the other hand, the message says that the restriction is ignored. 
It doesn't mean that the restriction relation in OSM is wrong or obsolete,
as it depends on the style and used options if any routable
way is available for that the restriction has an effect,
also, the input file might not contain the complete area,
so you always have to look at the OSM data.
If you use option --make-opposite-cycleways and remove the 
bicycle from the except list, the message should disappear.

By the way, I've also modified splitter to make sure
that it keeps all supported restriction types complete.

> 
> >> A future improvement could be to handle no_through_route or 
> >> no_through_driving restrictions, such as relations 2886802 and 
> >> 2886879.
> >> They are not describing the complete route; it is a bit ambiguous 
> >> what is meant by the relations (and the traffic signs).
> >
> >If I got that right, the meaning is that you are not allowed to drive 
> >into an area if you plan to drive through it. In my eyes this should be 
> >handled with the tag access=destination ?
> 
> It might not be that simple, because my understanding is that 
> access=destination would prohibit any through-routes, while only certain 
> through-route are being prohibited by the traffic sign. Looking more 
> closely at relation 2886803, the idea seems to be this:
> 
> ----------------A------------
> 		|
> 		| Mestarintie
> 		|
> --------B---+---+----
> 	|   |   |
> 	C
> 	| Panuntie
> 
> If you turn from A down to Mestarintie, you must not turn at crossing B 
> to Panuntie (C), but instead you must continue straight on to the left.  
> (If you stop for a while somewhere between A and B, then it is OK. It is 
> somewhat fuzzy and ambiguous, and seldom enforced, I guess.)
> 
> There could be some alternative routes A-B-C in that subnet, and I guess 
> that the no_through_driving should still apply, even if you did not use 
> the shortest route A-B-C.
> 
> An approximation of this restriction could be to prohibit driving only 
> on the shortest route A-B-C.

I see no simple way to support that, as it requires 1st to implement a 
routing algo, and I also doubt that we can translate that to the img
format. I agree to you 2nd post that mkgmap should only print
one message for this. 

Gerd

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