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

Wed Jul 6 12:18:02 BST 2011

Hi Marko,

Thanks for the explanation of things. Let me reply inline to some
specific comments.

On Wed, Jul 6, 2011 at 9:15 AM, Marko Mäkelä <marko.makela at iki.fi> wrote:
[snip]
>>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.
>
> Isn't it a bit redundant to add access=yes to ways? Usually, you would
> add access restrictions. I would say that this is a problem in the map
> data.

This is a good point. Looking at the taginfo:

http://taginfo.openstreetmap.org/keys/?key=access#values

'access = yes' is definitely being and it seems to be a valid
tag/value pair according the wiki. I think it would be a good idea to
remove the 'access = yes' from the OSM data. Perhaps we could remove
this tag/value pair when mkgmap is reading in the data? That way all
of the ways will be "normalized" to mean 'access = yes' if no access
tag is present. And then we could keep 'add access = no' for the
cycleways which would give the correct behaviour. I can see that my
'set access = no' with overwrite other types of access like 'access =
destination' so it's not a good way forward. Thoughts? I'd be happy to
make the patch.

>>I think it would be better to use the motor_vehicle tag to determine if
>>a cycleway is routable by car.
>
> To my understanding, mkgmap does not observe the motor_vehicle tag at
> all. It obeys motorcar and motorcycle. I do not know what happens if
> they contradict. As far as I understand, the Garmin map format cannot
> distinguish motorcar and motorcycle.
>
> Is it correct to use motor_vehicle instead of the more specific motorcar
> or motorcycle? A snowmobile is also a motor vehicle, but (depending on
> legislation) snowmobiles are not necessarily allowed on ways that are
> allowed for cars and motorcycles.

The more specific motorized vehicle tag (e.g. snowmobile) takes
precedence. I guess the moter_vehicle tag is mostly useful for
indicating that all motorize vehicle traffic is prohibited on a given
way.

> Come to think of it, for simplicity access=* should probably cover
> 'normal' vehicles. Motorized terrain vehicles should rely on specific
> tags, such as snowmobile=yes.

That sounds reasonable.

>>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?
>
> My understanding is that Garmin supports a few modes of transportation:
> foot, bicycle, motorcycle/motorcar, emergency, and possibly some others.
> Each mode has access bits, something like yes/destination/no.

Good to know.

Thanks, Ben