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