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

Mon Mar 24 13:52:47 GMT 2014

Hallo Gerd,

On Sun, Mar 23, 2014 at 06:16:27PM +0100, Gerd Petermann wrote:
>I've created a new branch via_ways to support this.
>It is nearly done, but I have to find solutions for
>some edge cases like via ways that cross tile boundaries.
>Also some routines like RoadMerger are not yet fully tested.

OK, let me know when you would like some testing.

FWIW, there were 4 relations with role=via ways that were not no_u_turn 
in Finland. I removed or replaced all of these today:

$grep "'via' ways are not supported" mkgmap.log.0|grep -v no_u_turn
2014/03/24 15:25:06 WARNING (RestrictionRelation): 63240004.osm.pbf: 
Turn restriction http://www.openstreetmap.org/browse/relation/2640984 
(at http://www.openstreetmap.org/?mlat=61.510688&mlon=23.777567&zoom=17) 
sorry, 'via' ways are not supported - ignoring restriction 
[type=restriction,restriction=no_left_turn]
2014/03/24 15:25:22 WARNING (RestrictionRelation): 63240002.osm.pbf: 
Turn restriction http://www.openstreetmap.org/browse/relation/1767298 
(at http://www.openstreetmap.org/?mlat=60.206666&mlon=25.120266&zoom=17) 
sorry, 'via' ways are not supported - ignoring restriction 
[type=restriction,restriction=only_straight_on]
2014/03/24 15:25:22 WARNING (RestrictionRelation): 63240002.osm.pbf: 
Turn restriction http://www.openstreetmap.org/browse/relation/67571 (at 
http://www.openstreetmap.org/?mlat=60.168673&mlon=24.935049&zoom=17) 
sorry, 'via' ways are not supported - ignoring restriction 
[except=psv;bicycle,type=restriction,restriction=only_left_turn]
2014/03/24 15:25:22 WARNING (RestrictionRelation): 63240002.osm.pbf: 
Turn restriction http://www.openstreetmap.org/browse/relation/1745548 
(at http://www.openstreetmap.org/?mlat=60.190691&mlon=24.962903&zoom=17) 
sorry, 'via' ways are not supported - ignoring restriction 
[type=restriction,restriction=only_right_turn]

I got the list with this patch:

Index: src/uk/me/parabola/mkgmap/reader/osm/RestrictionRelation.java
===================================================================

--- src/uk/me/parabola/mkgmap/reader/osm/RestrictionRelation.java	
(revision 3116)
+++ src/uk/me/parabola/mkgmap/reader/osm/RestrictionRelation.java	
(working copy)
@@ -281,7 +281,7 @@
		}
  
		if (result && viaWay != null) {
-			log.warn(messagePrefix + "sorry, 'via' ways are 
			not supported - ignoring restriction");
+			log.warn(messagePrefix + "sorry, 'via' ways are 
not supported - ignoring restriction " + toTagString());
			result = false;
		}
		return result;

IMO, a role=via way in anything else than restriction=no_u_turn is 
likely a mapping error.

The fixes I applied:

2640984: Split the 'via' way, make the part of it oneway. It is an 
oneway link between dual oneway lines in a T crossing. After the fix, 
you cannot drive against the oneway direction, and the no_left_turn 
restriction becomes redundant.

1767298: Remove the restriction. It was redundant, as the other turning 
target was tagged with oneway=yes, prohibiting the turn. In fact, all 
the ways in the T-shaped crossing were tagged oneway=yes.

67571: Remove one of the ways, make the role=via way the role=from way, 
and add a role=via node.

1745548: Make the left-turning lane branch earlier, according to the 
lane markings that are visible in Bing imagery. No turn restriction is 
needed, because the oneway=yes takes care of it.

BTW, while you are doing this, you could introduce warnings for 
redundant turn restriction relations (prohibiting turns against oneway 
direction).

Best regards,

	Marko
