Zumo550 detour and partially straight-line routing beside road

Hi All,

I’m not sure if my problem has been a topic here, searching the forum didn’t give me an answer.
I used “ready made” OSM maps of germany from different makers on my Zumo550 for many years with great success.

Now I let build a map on http://garmin.openstreetmap.nl (Generic Routable (new style)), containing germany/austria/switzerland, put it on the SD card and have two strange behaviours:
(the original Garmin map (City Navigator Europe NT 2008) resides in the internal memory, but is switched off).

  1. I made a route from Hamburg to Weimar (containing only start and destination points, option fast) and it goes a long way via Berlin which is definitely neither the fastest nor the shortest route.

  2. I added a third point on the Autobahn (of course on the south going lane) near Hannover which made the route nearly 50% shorter and faster. But now there are parts of the route consisting of strait lines going right beside the roads.
    I checked some other routes and this behaviour (route is leaving the road) occurs again.

Does anybody have an idea, what might be the reason?

Thank you in advance an regards


Does the zumo has a routable basemap? I know the nuvi has sometimes issues with those straight lines too. Don’t know how to solve this.