Unwanted road avoidance, Basecamp, Vietnam maps

I am preparing a route through Northern Vietnam, using Garmin Basecamp, latest version on a Windows 10 computer, and Open Street Maps. While working on the route – for an upcoming motorcycle tour – the route was suddenly changed by Basecamp, the software put in an unwanted and long detour. I used shaping points to correct it, no success. When this recalculation happened, I had not done any upgrading or changed any settings. Earlier the route was like I wanted it to be. Seemingly, the recalculation came out of nowhere.
I started from scratch, and made a new list and a new route, but still the software avoided the road I wanted to use. With several shaping points I managed to get there, but still Basecamp made two U-turns and a detour.
I deleted the map, and reinstalled, to no use. I have asked a Garmin Basecamp forum, apart from being advised to check the routing settings and avoidances – which I have done several times – no solutions came up.
So, my question to you: Can there be some bug in the map? I have used OSM before, without any problems. Any advice will be appreciated.


It has nothing to do with Basecamp, but with the OSM data.
Please check the route with the routing engine on osm.org. Then you can see that there is the same issue, it is simply caused by bad map drawing, two ways are not connected:

I’ve connected those roads, so this issue is solved after the next Garmin map update (depends on the map provider when the data is refreshed).

BTW: you can do a workaround in Basecamp to choose for direct navigation instead of car navigation for this gap.

Thank you, good to know what caused this. I guess I’ll delete my maps and then download a new set when the issue has been corrected. Joachim.

It is certainly possible that there’s a bug in the map. Places like Vietnam are not well covered by OSMers. It’s also entirely possible that Basecamp is the bad actor. It’s far from a perfect program and the free routable maps aren’t perfect either. I once experienced the same thing as you but in my case, I was able to check the OSM data to determine that it had no errors. I was frustrated to say the least. I solved the problem by creating the route in reverse order. I selected my terminal point first and the others in reverse order back to the starting point. Surprisingly, it compiled without error. Then, while still inside Basecamp, I reversed the route and downloaded it to my Garmin.

You can also move the route within Basecamp by clicking on it with the [Alt] key depressed. Then you can drag the line to the highways you prefer. I’ve had mixed success with this method but it works sometimes. Basecamp will automatically add sufficient via points to construct the route.

Problems can also result if you have more than one map covering the region of interest. I compile my own maps for smaller regions but keep an overall map on my unit in case I leave the area covered by my custom map. Routing can be very erratic in such circumstances, even if the second map is turned off in your unit’s routing settings.

Other readers may have more clues for you. Good luck.