[mkgmap-dev] Ferry line routing issue

Thu Jun 1 07:53:29 BST 2023

Hi

Not a real answer but perhaps do a quick check using another routable 
type (0x16) for ferries (0x1a or 0x1b) and see what happens.

r

Nick

On 31/05/2023 16:59, 7770 wrote:
> Hi.
> I can experience the same type of issues (or at least very similar) on my
> GPSMAP 66st (handheld outdoor unit) when trying to take a ferry from the
> Scandinavian peninsula to Europe.
> I have seen some of the jumps (straight lines occasionally).
>
> Here is some theory on the issue.
>
> Examples for such issues are Karlskrona (south of sweden) to Gdynia (north of
> Poland), or Stockholm to Helsinki. In those cases two the following can
> happen.
>
> When calculating for time, the unit may consider to drive around instead of
> taking the ferry, the ferry entrance would just be a stop along the route but
> the device would not consider taking the ferry, because it is presumed slower
> than driving many 100 kilometers extra or it simply times out saying there is
> no route possible to calculate.
>
> If i instead select calculating for shorter distance, the ferry is often
> considered and used by the route.
>
> Anyhow, in the style file for lines, there are two entries for ferry lines:
> route=ferry & (motorcar=no | motor_vehicle=no) [0x1b road_class=0 road_speed=0
> resolution 23]
> route=ferry [0x1a road_class=3 road_speed=0 resolution 19]
>
> If the ferry routes are expected to take cars the road_class will be 3 and and
> the road_speed 0, this road speed is so slow that the device will consider to
> use a faster way instead of taking the ferry.
>
> So, what i do to make it a greater chance that a ferry will be used when
> routing for time, is that i have raised the road_speed to 1 for those two
> lines, since it would also help for passenger ferries. I was tempted to raise
> it to 2 but many ferries are too slow for road_speed 2.
> This has somewhat improved routing scenarios in my case. It's not 100 %
> perfect but much better than before.
>
> I cant say it is exactly the problem that you see, but some idea.
>
>
> Regards
> Karl
>
>
>
> On onsdag 31 maj 2023 15:58:00 CEST Vukovics Mihály wrote:
>> Hello Community,
>>
>> I am struggling with an issue. I am generating Garmin map from OSM o5m
>> sources(geofabrik) using the built-in style.
>> Nor the BaseCamp or my Zümo 396LM is unable to calculate route via ferry
>> lines. The behaviour is very strange, here is an example:
>>
>> Route from Lille to Dover, all avoidances are disabled: unable to
>> calculate route, just a straigth line between the citie.
>> If I am forcing the route inside the service road area of Calais ferry
>> terminal, the route is calculated correctly.
>> Even funnier, that when I shape the route directly to the ferry line,
>> Basecamp swims me on the ferry instead of routing through the port.
>>
>> This behaviour is occuring with other ferry lines (for example Aberdeen
>> - Lerwick).
>>
>> I have checked on openstreetmap and the roads are connected and routable
>> in the style file.
>>
>> Here are the example screenshots about the issue.
>>
>> https://picallow.com/mkgmap-ferry-routing/?usp_success=2&post_id=116783&form
>> _id=27
>>
>> Any ideas or fix?
>>
>> Br,
>> Mihaly
>>
>> _______________________________________________
>> mkgmap-dev mailing list
>> mkgmap-dev at lists.mkgmap.org.uk
>> https://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev
>
>
>
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