Originally Posted by
ZeppoX
However, from the xray the luggage goes down two stories to ground level. Why not install the xrays down there? Possible answer: that would be in the sterile area, in which xray cannot be, and the geometry does not work to change it there, either.
I suspect it is a matter of space.
At CVG, FWIW, baggage is screened in the basement of T3 concourse B by the TSA. Concourse B is a seperate airside facility in the secure area (think of ATL's setup if you have never been to T3 CVG - you take an underground tram as a pax out to B).
First you have the departures level airside - go one level down to ground level and you have the FIS (US Immigrations & Customs) for inbound Intl. Go yet another level down and you have a good sized basement where luggage is screened. O/T: Go 7 levels up and you have the Delta Ramp Tower in the middle which oversees all 32 gates of Concourse B.
(Thank you, Delta, for the tour).
It could be done behind the scenes in a "sterile", off-limits area of the airport. At CVG they're building a full inline system in this area under T3 "B" so that most luggage won't even be touched unless it needs an inspection. For now they have to take it off the belt, screen it, and put it back on the belt.
I don't know how much room there is - if any - on the ground level of DCA or if there is a basement further beneath that which could be used to screen luggage inline. I suspect the room doesn't exist, thus the setup in the lobby.