A recent favorable vote in Loudoun on the Silver Line should make it much easier for employers to attract workers, and Ballard Spahr partner David L. Winstead said that also should result in an increase in high-density mixed-use projects in the area.

Mr. Winstead said a recent ULI study found that reduced travel time is the top cost benefit for mass transit. "Metro in Dulles Corridor could persuade more people to work in exurban locations," he said, which would result in more residential, office, retail, and hotel development.