[mkgmap-dev] routing problem on motorway ramp

Wed Mar 11 19:27:56 GMT 2009

Hi,

I've discovered some routing hickups I don't quite understand.

Here is a link to the motorway ramp/exit in question:

http://www.openstreetmap.org/?lat=50.90594&lon=11.0078&zoom=15&layers=B000FTF

Trying to route from the 'B4' (coming from north) onto the 'A4' going  
west fails.
It looks as if the ramp going onto the autobahn is not connected.

I've observed this behavior on my etrex legend (compiled with data  
some weeks old and mkgmap r925), but also today with recent data and  
mkgmap r975 routing with mapsource.

I've looked through the osm data (in JOSM) but found no  
irregularities. All nodes are connected, there's no oneway in the  
wrong direction or anything. The ramps are tagged with ref=A4;B4 which  
seems odd, but I don't know the proper handling of ramps regarding ref  
numbers.

To go east onto the A4 seems to be no problem. (To turn around on the  
next exit is the proposal mapsource gives to me to reach my goal). the  
only difference I can see between the western and eastern ramp is the  
node with the traffic lights.

Could someone investigate any further?

Thanks

Stefan