When driving with navigation, e.g. by NavMii (formerly NavFree), it may be good to know where construction sites are but is is no good idea to add them to the standard street map. OpenStreetMap should show the stable net of streets not temporary deviations, at least not with the same type than the normal road. If it should be possible to add deviations to the street map they should be of a separate type so the navigation software can discover that.

I just removed the deviation at the Schönbuch Tunnel when driving from Stuttgart to Singen because this side of the tunnel maintenance is finished already for some months. Still the navigation tells the driver to hold to the left to drive through the opposite tunnel.

I did not add the deviation for the opposite side as again someone would have to remove it when finished.

While correcting some other mistakes I encountered that it would make sense to be able to mark roundabouts as such, because sometimes, I suppose based on the fact whether the line has been converted to a circle or not, the navigation software discovers a roundabout and sometimes it does not and tells you to turn right and left to enter and leave it which can be quite confusing.

Finally I found that you can mark buildings as restaurants or cafes but not as hotels.