Data Mining in a Digital Map Database to Identify Insufficient Merge Lanes Along Roads and Enabling Precautionary Actions in a Vehicle

Disclosed is a feature for a vehicle that enables taking precautionary actions in response to conditions on the road network around or ahead of the vehicle, in particular, an intersection without traffic signals and without a sufficient merge lane. A database that represents the road network is used to determine locations where roads meet without a traffic signal and without a sufficient merge lane. Then, precautionary action data is added to the database to indicate a location at which a precautionary action is to be taken about the location of the insufficient merge lane. A precautionary action system installed in a vehicle uses this database, or a database derived therefrom, in combination with a positioning system to determine when the vehicle is at a location that corresponds to the location of a precautionary action. When the vehicle is at such a location, a precautionary action is taken by a vehicle system as the vehicle is approaching a location of an insufficient merge lane.