As anyone who’s ever boarded a Red Line train at rush hour knows, the Metro can get very crowded. And with the city’s population booming and a decreasing percentage of residents owning cars, it’s only going to get more crowded. There are essentially four things the city can do to reduce the Metro crush:

1. Discourage people from riding Metro. There are some positive ways to do this—-the rapid rise of Capital Bikeshare is one good example—-but for the most part, it’s a bad idea to discourage people from using the only transit form that reduces street congestion. Let’s nix this one.

2. Build more lines. Well, we’re building the Silver Line, but it’s really just an Orange Line spur. If city officials could wave a magic wand and make one thing happen, it’d probably be a few new Metro lines relieving overburdened stations like Union Station and serving limited-transit neighborhoods. In the real world, however, building a new line is both extremely expensive and extremely disruptive. Plus it’s not even clear that adding lines would relieve congestion enough to offset the greater number of people who’d have access to Metro.

3. Increase the capacity of existing lines. More frequent trains would be great, but they don’t come cheap. Metro is working to add more eight-car trains to the system. That’s probably about all we can expect in the immediate future.

4. Encourage reverse commutes. Bingo. During the morning rush, packed trains approach the downtown core, then travel practically empty to the periphery; in the evening rush, it’s the reverse. So wouldn’t it be great to get some people moving in the opposite direction? The advantages of this solution are twofold. One: Metro doesn’t have to spend a cent. Two: It’s already happening on its own.

And that’s why Metro loves it, as the Metro blog PlanItMetro highlights in a new post. The author of the post breaks Metro morning commutes down into six categories: traditional commutes from the periphery to the core (defined as stretching from Foggy Bottom to Gallery Place and from Farragut North to L’Enfant Plaza); suburb-to-suburb trips passing through the core; trips in the peak direction that stop short of the core; trips in the reverse direction that start outside the core; reverse commutes from the core to the periphery; and trips within the core.

The methodology’s not perfect, but the results are nonetheless telling. “Traditional” commutes from the periphery to the core have declined as a percentage of morning trips, from 54 percent in 2002 to 50 percent in 2012, while growing in absolute terms by just 2 percent. At the same time, reverse commutes that take place outside the core have increased by 49 percent, rising from 3 percent of trips to 4 percent, while reverse commutes from the core have increased by 34 percent, likewise going from 3 percent of trips to 4 percent.

There are two ways for reverse commuting to increase: more people working outside the core or more people living in the core. The PlanItMetro post focuses on the former, highlighting the top reverse-commute destinations. (Bethesda, Medical Center, and Crystal City lead the way.) Within the District, too, some noncore destinations have seen their numbers of commuters spike. Looking at the raw data, we see, for example, the average number of daily commuters to Navy Yard from Greenbelt spiking from 42 in 2007 to 112 in 2012, or to Navy Yard from Southern Avenue jumping from 27 to 87.

But what about the other solution, getting more people to live in the core? This one serves a dual advantage: Some people living in the core will walk to their work in the core; others will reverse-commute to their jobs in the periphery. The problem is that there still isn’t that much housing downtown. That’ll start to change as projects like CityCenterDC come online, but if we really want to encourage reverse-commuting, we’ll have to do more to change the office domination of downtown.

Image from PlanItMetro