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[mkgmap-dev] Data / routing issue - Vancouver, BC ferries

From Gerd Petermann GPetermann_muenchen at hotmail.com on Sat Jul 29 08:44:00 BST 2017


I think this problem still exists. I downloaded british-columbia-latest.osm.pbf and tried again today.
Some routes changed, but overall ferry routing in this area is a mess.
I think one reason is that the ferry lines are split, so that many lines connect somewhere in the ocean, e.g. here:
This alone should not be a problem, but some of the ways ending at this node have refs and others do not. In fact all ways
going south from this point have the same tags, none has a ref tag.
Another problem might be that those ways are connected with rather sharp angles.
The road merger doesn't seem to be able to connect the parts.

I don't know why the ferry lines are split, but I would say this is very uncommon and probably also wrong
because it somehow means that you have to jump from one ferry to another in the open sea.

So, I think the problem here is in the data.


Von: Gerd Petermann <gpetermann_muenchen at hotmail.com>
Gesendet: Mittwoch, 14. Juni 2017 18:30:40
An: Development list for mkgmap
Betreff: AW: Re: [mkgmap-dev] Data / routing issue - Vancouver, BC ferries

I do not yet believe that the service roads are causing this. I saw +1000<tel:+1000>km detours when reverting a much shorter route. I cannot test it during the next weeks
Ciao Gerd

---- Samuel Longiaru schrieb ----

Hi Andrzej,

I like the simplicity of the tag idea, but implementation I'm sure would
be rather spotty.  Adding the logic to mkgmap would make more sense I
think as it would be immediately and universally applicable.  As you
say, there may be even more cases beyond the ferry setting where such
logic could be applied, and if not accommodated by mkgmap, would need to
be re-tagged in OSM.

On 17-06-14 05:17 AM, Andrzej Popowski wrote:
> Hi Sam,
> ferries get class 3 for routing, which is high. They should be easily
> used in routing when allowed in GPS.
> If the problem really is low routing class of service roads, then I
> see 2 solutions:
> Convince OSM mappers to add more tags for "highway=service". This
> could be for example "service=ferry". Or add any other indication,
> that these roads carry important traffic, for example include roads in
> a relation. Then this could be processed by mkgmap.
> Second solution would be to try to catch the problem by mkgmap. I
> think there are more similar cases, where 2 important roads are
> connected by a link or roundabout with significantly lower routing
> class. Mkgmap could include following algorithm:
> Find all suspicious objects, like highway links, roundabouts, service
> roads connected to a ferry and analyze other roads connected to this
> object. If any of these other roads get road_class 3 or 4, then
> increase road_class of processed object accordingly to 3 or 4.

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