Newly Upgraded White House Fence Defeated by Infant Intruder

To me, the most interesting detail in the story: “While taller, the new fence has an additional inch of space between the pickets, for a total of 5.5 inches (12.7 centimeters) between posts.” https://t.co/kmWKskK0Sa

— TSB (@TweetingTSB) April 18, 2023

So, for lovers of trivia and minutia, can you guess how actual security design professionals determine how close is close enough for the spacing of pickets in a high-security fence? 

Hint: the human head is the most irreducibly small element that an intruder has to push through an opening. No matter how skinny a body may be in all other dimensions, the adult head can't get smaller.

How large is that typical adult head, and how would you know? Sample hat sizes? Conduct experiments? Survey your friends?     

Thanks to the U.S. taxpayer, none of that is necessary because the motherlode of body measurement data comes to us from the U.S. Defense Department. If you are prepared to be suitably impressed, go to page 478 at the linked report and check the head measurement known as the 'bitragion breadth.' 

That's the smallest head dimension relevant to a picket fence. An intruder must get that front width of his head through an opening if the rest of his body is to follow. 

I urge you to really appreciate the scientific legitimacy of DOD's anthropometric data. Go deep into the dork forest of sample sizes and standard deviations. 

Thanks to that good work, we can say with a high level of confidence that 5.5 inches of clear opening distance between the pickets of the White House fence is enough to stop nearly all intruders (not counting infants, of course), without being ridiculous or unaffordable. 

A tip o' my government hat to whoever worked on that project.