Section 420.70 - Separation distance measurement requirements(a) This section applies to all measurements of distances performed under §§ 420.63 through 420.69 .(b) A launch site operator must measure each separation distance along straight lines. For large intervening topographical features such as hills, the launch site operator must measure over or around the feature, whichever is the shorter.(c) A launch site operator must measure each minimum separation distance from the closest hazard source, such as a container, building, segment, or positive cut-off point in piping, in an explosive hazard facility. When measuring, a launch site operator must: (1) For a public traffic route distance, measure from the nearest side of the public traffic route to the closest point of the hazard source; and(2) For an intraline distance, measure from the nearest point of one hazard source to the nearest point of the next hazard source. The minimum separation distance must be the distance for the quantity of energetic liquids or net explosive weight that requires the greater distance.Doc. No. FAA-2011-0105, 77 FR 55116 , Sept. 7, 2012