[mkgmap-dev] Inter-tile routing now available in trunk

Mon Mar 2 19:19:46 GMT 2009

Dermot McNally wrote:
> 2009/2/28 Mark Burton <markb at ordern.com>:
> 
>> Yes, I think that is the key to getting good routes. Somehow, you need to
>> make the GPS want to use the motorways rather than the trunk roads.
> 
> As long as we're on the topic of speed profiles of road types - I've
> seen a case where my Nuvi needs to route from one motorway to another.
> It's basically the route as shown here:
> 
> http://data.giub.uni-bonn.de/openrouteservice/index.php?start=-6.2430356,53.410256&end=-6.2214921,53.4198222&pref=Fastest&lang=de
> 
> You can see here that OpenRouteService chooses a sub-optimal route, in
> favouring a short spell on the roundabout over a longer stretch
> (leading to an overall shorter route) on a motorway_link.
> 
> In any case, the Nuvi makes the same mistake. Do roundabouts need to
> be de-prioritised somehow?
> 
> Dermot
> 

I have to say that I've not seen this before. Whenever I encounter a
similar situation there's no problem. See below for an example.

http://data.giub.uni-bonn.de/openrouteservice/index.php?start=-6.2430356,53.410256&end=-6.2214921,53.4198222&pref=Fastest&lang=de

Your example clearly behaves differently but I can see no reason for it.
If I had to guess I'd say that it's due to the very shallow angle
between the start of the link road and the main carriageway as I can't
see any reason for it in the data

Additionally the following shows that for the same roundabout
approaching from the South then the behaviour is as expected

http://data.giub.uni-bonn.de/openrouteservice/index.php?start=-6.2430356,53.410256&end=-6.2214921,53.4198222&pref=Fastest&lang=de

Cheers

Paul