"More stations and tunnels are needed, Metro officials argue. Not to reach new and different parts of the region, but to take the pressure off its most heavily used and crowded lines," writes Jonathan O’Connell
Metro’s biggest choke point is already in Rosslyn, where rush-hour commuters in both directions regularly see filled-to-the-brim train cars pass them by. Metro began raising the possibility of a new underground tunnel between Rosslyn and Georgetown nearly a year ago, part of $26 billion in overall improvements the agency has proposed.
Metro planners also dismissed the idea that other transit modes could alleviate the congestion, arguing "that adding longer cars or building various streetcar, light-rail and bus rapid transit systems that have been proposed for the region isn’t likely to be sufficient to solve the problem," writes O’Connell,
According to a report [PDF] released this month from George Mason University’s Center for Regional Analysis, "one in seven [14 percent] of the region’s commuters use public transit." However, the subscription rate varies by geography, with close-in suburbs using it at much higher rate.