[mkgmap-dev] Route Calculation Error and Ferries

Tue Mar 13 17:11:38 GMT 2018

Hi Gerd, Andrzej

I've done a bit more experimenting with Basecamp.

Starting from a fixed point on a main roundabout on the mainland, I've
been creating routes to a Primary road on the Island, working along
this road until it fails to use the ferry and resorts to a straight
line.

Using GPSMapEdit to look at the road segments, positions of routing
nodes and other properties, it appears to work on one side of a routing
node but not the other on a single line segment. 

Ticker

On Tue, 2018-03-13 at 14:46 +0000, Gerd Petermann wrote:
> 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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