[mkgmap-dev] problem with highway=cycleway in default style

Tue Jul 5 11:37:14 BST 2011


On 05.07.2011 12:34, Ben Konrath wrote:
> Hi everybody,
>
> I've found a problem with the highway=cycleway in the default style.
> The current setting from the default lines file is this:
>
> highway=cycleway {add access = no; add bicycle = yes; add foot = yes}
> [0x07 road_class=0 road_speed=1 resolution 23]
>
> One small problem is that the cycleway should probably be listed as a
> path or trail (0x16) instead of alley (0x07).
>
> The bigger issue, however, is that the extra tags which are added to
> highway=cycleway makes cycleways routable by car under certain
> circumstances. The problem comes from the way that the access tag is
> used in the style file. The access tag in OSM describes legal access
> to a given highway:
>
> http://wiki.openstreetmap.org/wiki/Key:access
>
> A tag with 'access = no' means that the general public is not allowed
> to go on that particular highway. Likewise, 'access = yes' means that
> the general public is allowed to use that highway. And then there's
> specific types of access in between yes and no for specific types of
> traffic as listed on tag's wiki page.
>
> In the default style of mkgmap, it seems that the access tag is used
> to represent whether or not a particular highway type is routable by
> motor vehicle. If you have have cycyleway that is tagged with 'access
> = yes' - meaning the public is allowed use that cycleway - the 'add
> access = no' rule will not overwrite the access rule in the OSM data
> and the cycleway will be routable by motor vehicle. An example of this
> can be found in Red Deer, Alberta, Canada on the Bob Johnson Trail:
>
> http://www.openstreetmap.org/?lat=52.276167&lon=-113.804459&zoom=18&layers=MOn
>
> To solve this problem, I've changed 'add access = no' to 'set access =
> no' so that the access tag will be overwritten and cycleways will not
> be routable. But this seems to be a hack because it's not really
> describing the OSM data correctly. I think it would be better to use
> the motor_vehicle tag to determine if a cycleway is routable by car.
> The motor_vehicle tag is described on the 'access' tag's osm wiki page
> above. Here's the proposed style for cycleways:
>
> highway=cycleway {add motor_vehicle = no; set bicycle = yes; add foot
> = yes} [0x16 road_class=0 road_speed=1 resolution 23]
That wouldn't change anything. 0x16 is routable by motorcars too. Add is 
correct, as in some places people seem to think that cycleways are 
usable for cars (for short distances and so on). Else use set access=no; 
set bicycle=yes; add foot=yes.
>
> This would prohibit motor_vehicle routing on cycleways by default if
> the cycleway if the cycleway doesn't have a motor_vehicle tag. This
> would also allow motor vehicle routing on cycleways that allow it as
> described in this thread from last month:
>
> http://www.mkgmap.org.uk/pipermail/mkgmap-dev/2011q2/011771.html
>
> We'd still have to support the OSM access tag somehow. I did a quick
> grep through the mkgmap source and it seems that there isn't support
> of the motor_vehicle tag. I would like to make a patch to address this
> issue but I have a couple of questions first. Is the access tag used
> to describe motor vehicle access in mkgmap? Does the garmin format
> support the idea of public / private access separately from motor
> vehicle access?
>
> For now, I'm using the attached patch prohibit . I've change 'add
> bicycle = yes' to 'set bicycle = yes' because anything tagged a
> cycleway must allow bicycles by definition.
>
> Thanks, Ben
>
>
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