A database that represents the road network is used to determine locations where an intersection of roads is located at the bottom of a hill and then, precautionary action data is added to {HEAD ~ the database} to indicate {TAIL ~ such locations} 
A database that represents the road network is used to determine locations where an intersection of roads is located at the bottom of a hill and then , precautionary action data is added to { HEAD ~ the database } to indicate { TAIL ~ such locations }
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