The brief video animation includes an exterior fly over of the soaring glass pavilion that will house new security checkpoints, leading in to Terminals B and C. The preview is likely to elicit “ohhs and ahhs,” but may also leave travelers wondering how the authority will be able to complete the project and keep traffic around the airport moving. MWAA officials concede it won’t be easy. Much of the work will be done at night when there is less traffic. While some preliminary work is set to be done this fall, much of the major work, including demolition of the airport’s executive offices to make way for a new short-hop terminal, won’t begin until next spring. The last major building project at National was the addition of Terminals B and C, which opened with fanfare in July 1997. The 1.1 million-square-foot addition was designed by César Pelli, who once worked for Eero Saarinen, the Finnish-American architect who designed the iconic terminal at Dulles International Airport.