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