[mkgmap-dev] Turn restriction for highway=motorway[_link]

Wed Aug 4 13:04:55 BST 2010

On Wed, Aug 04, 2010 at 09:07:27PM +1100, Hendrik Oesterlin wrote:
>"Carlos Dávila" cdavilam at orangecorreo.es wrote on 04/08/2010 at 20:14:50 +1100
>subject "[mkgmap-dev] Turn restriction for highway=motorway[_link]" :
>
>> El 04/08/10 10:14, Hendrik Oesterlin escribió:
>>> Hello,
>>>
>>> I have some trouble to make turn restrictions work properly. I think
>>> it is because mkgmap is failing to make them work if the highway types
>>> are "motorway" or "motorway_link". The roads are behaving a bit like
>>> "oneway=yes" in some directions. A very unpredictable thing.
>>>
>>> Is this a known behaviour? I am not jet 100% sure that the issue is
>>> really triggered by the "highway=motorway". But maybe someone before
>>> has already spend enough time to do all the trial-and-error testing
>>> for this...?
>> If you are using the dafault style, these lines in the lines file may be
>> the key:
>> highway=motorway {add oneway = yes; add bicycle = no; add foot = no }
>> [0x01 road_class=4 road_speed=7 resolution 14]
>> highway=motorway_link {add oneway = yes; add bicycle = no; add foot = no
>> } [0x09 road_class=3 road_speed=2 resolution 16]
>
>> In my customized style I have removed add oneway = yes from the
>> motorway_link line.
>
>Thank you for your hint! This is probably the problem.

Wouldn't it be a problem of the source data? In my part of the world, 
motorway links tend to be entering or exiting the motorway at a very 
small angle, and are inherently oneway. Can you post a link to a twoway 
motorway link? Do you suggest that I should remove the oneway=yes from 
the default style?

Best regards,

	Marko

PS: not all turn restriction traffic signs need turn restriction 
relations. For example, if you exit this parking ramp to the north 
http://www.openstreetmap.org/browse/way/46098413 you will see a sign 
that forbids a left turn. I did not add a turn restriction for it, 
because the way to the left is already oneway (forbidding the turn).  
Could it be that mkgmap or Garmin is misbehaving when you try to add 
such a "redundant" turn restriction?

PPS: I have been using Google Street View (when available) when in doubt 
(or when I do not remember why I pressed the Lap button to create a 
waypoint when recording a GPS trace). It is a welcome addition to aerial 
imagery and other sources.