A cumulative threat risk value for {HEAD ~ each} of {TAIL ~ the grid cells} is calculated, and an allowable threat risk per grid cell is established based on a rule set 
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A cumulative threat risk value for { HEAD ~ each } of { TAIL ~ the grid cells } is calculated , and an allowable threat risk per grid cell is established based on a rule set
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH