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

Wed Aug 4 16:10:56 BST 2010

On Wed, Aug 04, 2010 at 04:55:42PM +0200, Carlos Dávila wrote:
>El 04/08/10 14:04, Marko Mäkelä escribió:
>> 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?
>>
>In most cases motorway links are separate oneway roads, but, at least in
>Spain, sometimes both directions share the same road. See way 70904729
>in the area below
>http://www.informationfreeway.org/?lat=38.107106989860675&lon=-6.2724820671928425&zoom=15&layers=BF00F0

The default style does "add oneway=yes", not "set oneway=yes". You could 
fix this by adding "oneway=no" to the two-way section of 
highway=motorway_link. Actually, I see that you already did that, in the 
initial version:

http://www.openstreetmap.org/browse/way/70904726

Unless you can provide an example where a two-way motorway link that is 
tagged as oneway=no is misbehaving, I think we should leave the default 
style as is. (A lazy mapper could forget the oneway=yes, assuming that 
"everyone knows" that motorway links are oneway, and you could get bogus 
instructions "leave the motorway at the next entry (not exit)".)

Best regards,

	Marko