The ol’ Washington Post peeps into the new underground AeroTrain system at Dulles International Airport today, which will replace the 1960s-era “mobile lounges” — essentially giant shuttle buses — that scuttle around the Dulles tarmac, ferrying passengers between terminals.

The AeroTrain is similar trains that operate at Atlanta’s Hartsfield-Jackson International and at Dallas-Fort Worth. Writes the Post’s Eric Weiss:

“Initially, there will be four stations serving the airport’s main terminal, A gates, B gates and C gates in a J-shaped configuration. Construction started in 2002, and tunneling was completed in 2006. The stations are not yet finished, and testing must be done before the trains begin carrying passengers in fall 2009.”

If you’re in the mood, check out this eerily silent promotional video from the Metropolitan Washington Airports Authority.

Got a favorite airport tram or transportation system? Let us know in the comments below.

Image: Washington Post