[mkgmap-dev] Route Calculation Error and Ferries

Tue Mar 13 14:46:41 GMT 2018

Hi Ticker,

I think what Andrzej wants to point out is that Garmins routing algo is quite special.
When looking for a possible route it tries to reach a road with a high class. Once  this is found
it will ignore roads with lower class if this is the only connection to the ferry (which also should be
a high class, default style uses 3). I think this search is done from start and target.
So, if a class=3 road takes you close to the ferry terminal but not onto the ferry you might see these
problems when your route includes the class=3 road.
I wonder if this also happens for pedestrian routing, but for cars I've often seen that.

Gerd

________________________________________
Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von Ticker Berkin <ticker at jagIT.co.uk>
Gesendet: Dienstag, 13. März 2018 15:09:50
An: mkgmap-dev at lists.mkgmap.org.uk
Betreff: Re: [mkgmap-dev] Route Calculation Error and Ferries

Hi Andrzej

No - I checked all of this. A couple of ferries wouldn't route to/from
the public highway network because of this (access=destination), but
one didn't have this tagging on its service roads and Basecamp would
route using the ferry as long as the start and end points (on public
roads) were close to the ferry terminals, but trying to start/end
further away,  still on connected public roads, it wouldn't route.

Ticker

On Tue, 2018-03-13 at 14:11 +0100, Andrzej Popowski wrote:
> Hi Ticker,
>
>  > as long as the start and/or end points are only a few streets away
>  > from the ferry termini
>
> This could be because of service roads leading to a ferry. That kind
> of
> roads are the last resort for a route and usually at the endpoint
> only.
> They are probably ignored, when calculating longer route for a car.
>
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