Instead, passengers board a modular "capsule" at the railway station. The train delivers the capsule to the airport where it is attached to a "flying wing." Engines, cockpit, and fuel are in the wing — passengers never enter the terminal. The wing, furthermore, can carry a mix-and-match assortment of passenger and/or cargo capsules.
More here:
http://www.gizmag.com/clip-air-modular-aircraft-epfl/27861/