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David Colarusso

David Colarusso

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Full-Body Scans v. Nude Screenings: A Back-of-the-Envelope Calculation

Posted: 01/ 4/10 11:46 AM ET

I'm currently trapped in an airport terminal waiting for my delayed flight, and in the wake of the Christmas day terrorist attempt, I can't help but ponder the question of full-body scans. Ambivalent as I am, I figure this is as good a time as any to weigh the pros and cons. Quite bluntly, security wants to see under our cloths, presenting at least two options: (1) walk through security screenings naked; or (2) submit to full-body scans. I have to admit, the latter seems more appealing. However, if I'm entirely honest, I can't see a functional difference between the two. Proponents of body scans are quick to point out that faces and privates may be obscured electronically, but all this really means is that "naked" screenings would allow masks and underwear. Then again, our would-be bomber apparently used underwear to smuggle explosives. So maybe we shouldn't blur/cover those bits. I've also heard people say that body scans aren't very clear, presumably based on the censored images they've seen on the news. So I suppose naked screenings could take place behind frosted glass. If you've actually seen uncensored backscatter images, however, I think you'll agree, they look like poor-quality naked pictures. Sure naked screening would require building special hallways with changing rooms on either end, but we could place one-way mirrors in the hallways, separating screeners from passengers. We could provide masks to obscure faces.1 Passengers could walk through one at a time, and we could make use of same-sex screeners. This would make the two options functionally equivalent.

At first, we may think the naked option is more cost-effective. A body scanner can cost as much as $200,000.2 So assuming a single machine accommodates 1,200 travelers a day,3 and about 2 million people fly in the US every day,4 we would need around 1,700 scanners at a cost somewhere around $340 million. I'm not sure how much it would cost to build a hallway with changing rooms, but a small hallway and two closets take up about 5% of my $130,000 condo, and most of that's property value, not construction cost. So let us say screening hallways cost $3,000 a piece. The naked method would be slower than a body scan. So instead of 1,200 travelers a day, let's say it accommodate 600.5 Consequently, we would need around 3,300 hallways at a cost of about $10 million. I am willing to bet the operational lifespan of a hallway exceeds that of a body scanner. So if a body scanner lasts five years and a hallway thirty, the lifespan-adjusted-annual cost of the two comes out to $68 million for the scanners6 and $330,000 for the hallways.7 Now, we have to take into account staffing. I'm going to assume that scanners take two employees for every one needed by a hallway, given their technical nature and maintenance needs. Assuming that these employees are payed $20 an hour, this translates into $500 million a year for scanners and $480 million a year for hallways. Adding staffing to technology costs, scanners would cost about $570 million a year, while hallways would cost about $480 million. Divide these numbers by the total number of travelers in a year (~700 million)8 and we find that body scanners cost about $0.81 per passenger while hallways cost about $0.69.9 This isn't the end of the story, however, because there's an opportunity cost on the part of the passenger. If your time is worth more than $0.12 an hour, the scanner is the better option. Otherwise, you should take the hallway.

I bet most people would pay twelve cents to take the scanner over the hallway. Of course, this is the wrong way to think about it. That twelve cents is the cost of a saved minute. There's no other functional difference between the two options. Imagine, however, that both methods take the same amount of time. How much would someone have to pay you to take the hallway? Multiply that by the 700 million people flying annually; add it to the $570 million required to run the scanners for a year, and you've got a better idea of how much body scanners really cost. I don't know if that money could be better spent on human intelligence or some other form of terrorism prevention. I don't even know if I care who sees me naked, but I do know the discussion surrounding full-body scans hasn't been entirely rational. Where are the pundits calling for naked-hallway screenings? We could save the taxpayers hundreds of millions of dollars a year. How do you think it all adds up?

1: I suggest Guy Fawkes.
3: 60 min an hour X 20 hours of operation / 1 min per scan
5: 60 min an hour X 20 hours of operation / 2 min per screening (I imagine people will hurry through this.)
6: Cost of 1,700 scanners / 5 years
7: Cost of 3,300 hallways / 30 years
8: supra note 4
9: If you think these numbers are anywhere near accurate, you've missed the point. Heck, I wrote this in an airport. Oh, and thanks Google for the free holiday wifi.


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