Hi Thorsten,
Thanks for your reply. This type of restriction is probably a country specific thing. In Ontario Canada, you can make u-turns at intersections (regardless of the road is separation) if there is no sign indicating that you can't make the u-turn. Here's the information directly from the Ontario Ministry of Transportation:
http://www.mto.gov.on.ca/english/dandv/driver/handbook/section2.6.11.shtmlI realize that the link I sent previously is in the US but I suspect that it's the same policy there which is why the restriction is tagged like it is.
Since the tagging seems to be valid, does the Garmin format support this type of restriction? If not then it's probably a good idea to indicate this in the warning message. Maybe the message should also be changed to an info message if there's no problem with the data. Does anybody have other insights?