I can't go anywhere without analyzing operations and workflow -- there used to be a bagel store near my house whose work flow was so awful and inefficient it almost caused me physical pain just to be in the store. In large part I owe my marriage to operations analysis, as I started going out with my wife when I was tutoring her on cycle times and other basic concepts.
So beyond the obvious privacy and invidual rights problems, TSA screening areas have always driven me nuts because they are so inefficient. Yesterday I was putting on my shoes and belt after another run-in with the visible hand of the state, and it gave me time to watch the full body x-ray scanners for a while. They had been bought in sufficient quantity to replace the metal detectors one for one, but there seemed to be a problem.
While people flowed through the metal detectors, at a rate of at least 15-20 per minute, the full body scanner seemed really slow. In fact, I sat down and timed it for a while. The scanner was working at a rate of 3 people per minute. This was with a queue at the front end so there was no waiting time for a new person to enter when the scanner was ready. A couple of times it did 3.5 per minute, but never did it do 4 in a minute. This seems like a real problem -- that capacity per lane has been reduced by a factor of 5 or so from the metal detectors. Of course, it is a bit more complicated than that, because a parallel process of scanning the luggage in the x-ray machine has to complete simultaneously, and before the new scanners the x-ray was definitely the bottleneck. But each time I went through this week my luggage sat complete on the x-ray machine before I finished being scanned, which suggests to me that the bottleneck has shifted, and we have spent a lot of money to slow down an already time consuming process. That is why most airports have kept their metal detectors --they need them for overflow capacity.
Here is a second issue with the scanners -- they appear to take 3 times as much manpower. The old metal detectors required one person. The new machines appear to require 3 -- one person is at the machine, giving instructions; a second person watches you in a sort of holding area downstream of the machine as you wait for the scan results; and third person is somewhere out of site, on a radio, presumably looking at monitors and calling in results to the second person. No wonder the TSA loves this technology - 3 times more staffing!