Originally Posted by
Koby
It's not that complicated. I know lots of airports (BRU and BCN come to mind) where you have to go through a double set of automatic doors to leave the secure area. They are just wide enough for one person. If anyone tries to pass them in the wrong direction an alarm sounds. (And the doors stay closed.)
And yes, this type of doors existed already pre-9-11.
Think of how much money (and embarrassment) that TSA could save by installing doors that only allowed one-way passage... If somebody tries to go "upstream", have some sort of system to trap them between the doors until a LEO arrives..