All of the new U.S. superjets were there: Lockheed's L-1011, the McDonnell-Douglas DC-10 and Boeing's giant 747 freighter. Overhead, jet fighters of the U.S. Air Force's Thunderbirds, the Navy's Blue Angels and the R.A.F.'s Red Arrows performed dramatic aerial acrobatics. But the real stars last week at Transpo 72, the $10 million Department of Transportation show at Dulles International Airport near Washington, were little vehicles that will never leave the ground: the Personal Rapid Transit systems, or PRTs.
Designed to shuttle passengers quickly and efficiently around crowded metropolitan areas, airports, university campuses and large shopping centers, the electrically powered "people movers" have...
