I have used OSM maps in Thailand and SE Asia for several years and they are quite good for the most part. But they do contain errors, as do Gamin maps. The difference is that anyone who cares to can fix the OSM errors. The OSM project is like Wikipedia in that it has the potential to replace Gamin maps just as Wikipedia has largely replaced printed encyclopedias. It's all done by thousands of volunteer mappers around the world, some of whom are very sophisticated programmers and geographers. Consequently the OSM map of the world is being continuously updated and corrected.
I live in northern Chiang Mai, Thailand, and currently the OSM maps are more accurate than Google Maps in my neighborhood. Why? Because several map makers including myself live here and are working to add and correct the maps ourselves. Read my blog article
for an intro and an explanation of how I got involved.
The other night I was driving to a place I knew well but I used my GPS to route me there. As in your case I experienced a problem. The street I was traveling became one-way, for a single block, going in the opposite direction. After I got home I edited that street's properties. Next time I do that route, my GPS will be able to compute it correctly. If this sort of thing happens with a Garmin map you need to write them an email explaining it all. Then you can sit back and wait for a few months or years until the changes appear. My OSM edits will appear in a couple of weeks. And when they do, it's immensely satisfying.
Originally Posted by wbbnm
Sounds like a missing road segment. I experience that sometimes even in Garmin City Navigator.
In these cases I convert the route to a track and go in and edit the track to fix the problem and then navigate using the track. Like the guy said you have to be smarter than the machine.
I looked into OSM a year or so ago. I checked dirt roads in some remote areas I know pretty well and found a few errors. It was enough to make me not want to rely on these maps in remote areas that I don't know.
And my reaction was "You get what you pay for".