{HEAD ~ 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 the database to indicate {TAIL ~ such locations} 
{ HEAD ~ 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 the database to indicate { TAIL ~ such locations }
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