The Interdependence of Land Use and Transportation

» Northern Virginia’s growth patterns demonstrate the degree to which transit can play an essential role in spurring inner-city growth.



There is little need for data to demonstrate just how important the Washington Metrorail system has been for Arlington, Virginia’s growth over the past few decades. Visit anywhere along the Rosslyn-Ballston Corridor or in Crystal City — the two areas best served by Metro — and you’ll see dozens of new residential and office buildings lining the street.

But new information from Census 2010 provides empirical confirmation of the significance of land use planning around Metro stations in influencing the growth of Arlington and other places in Northern Virginia. Over the last ten years, Arlington County’s growth has been overwhelmingly concentrated along the Metro corridors, as has growth in Alexandria and some parts of Fairfax County. The densification of these areas is effectively extending the inner-city core of the Washington, D.C. region and substituting sprawling development in the exurbs with dense construction. This represents a change in trends compared to the period between 1990 and 2000.

As the map above shows, the areas of Northern Virginia that saw the greatest percentage growth between 2000 and 2010 were all clustered around Metro stations — in Arlington along the Rosslyn-Ballston Corridor (Orange Line) and in Crystal City (Yellow and Blue Lines); in Alexandria near Van Dorn Street Station (Blue Line) and Eisenhower Avenue (Yellow Line); and in Fairfax County near Vienna/Fairfax Station (Orange Line). As other areas of close-in Virginia have been fully developed, these station area zones have densified through the coordinated planning decisions of city officials, the availability of rail rapid transit, funds from developers, and a clear interest of a large portion of the population to inhabit the new buildings.

In the case of the Rosslyn-Ballston Corridor, the Census Blocks within closest proximity of the five Metro stations along the Orange Line absorbed more than 70% of Arlington County’s growth, increasing by 12,816 people compared to Arlington’s expansion by 18,174 people towards a total population of 207,627. These 1.47 square miles arrayed linearly — a small percentage of Arlington’s 26 square miles — now represent more than 17% of the county’s population, compared to about 12% in 2000.

What effect has this localized growth had on the face of the region in general? Let’s compare Arlington to an exurban locale that has been recently developed.

The Broadlands neighborhood, about 30 miles from Downtown Washington in Loudoun County, has been mostly built up over the past ten years, its population exploding from about 3,500 to 12,800 on a 3.22 square mile site (this includes some areas which were developed as part of another neighborhood). It is just to the northwest of the planned Route 772 station at the terminus of the now under construction Dulles Metrorail Extension (Silver Line), which will connect Arlington to Tysons Corner and Dulles Airport.

As is made evident in the drawing above, the Rosslyn-Ballston Corridor absorbed a new population equal to the total population now living in the Broadlands area (the scale of each community is the same). In essence, this means that the the population increase that was made possible through the densification of this area of Arlington via infill development was equivalent to the construction of a greenfield exurban development almost three times its total size. If the Corridor had seen no population increase at all over the past few years, the region would have needed to find housing for almost 13,000 more people. In all likelihood, that would have been in more places like the Broadlands.

Moreover, Arlington’s growth was done in a way that includes a diversity of building types and uses and integrated rapid transit, limiting the need for individuals there to rely on private automobiles. It was a result of projects like this that gave the Washington region the third-highest transit mode share in the nation, after New York and San Francisco; more than 40% of people in the Census Blocks around the Rosslyn-Ballston corridor use public transportation to get to work. Traffic along the corridor has not increased despite the large increase in population.

In the Broadlands, the dominant building type of single-family homes and a lack of retail and service options mean that most people will need to drive to get anywhere. Even when the new Metro station is completed, most people will not walk to it because of a lack of a friendly walking environment. And congestion along area roads will undoubtedly increase substantially.

For growing cities and metropolitan areas, this comparison illustrates a stark choice: Do we want to find ways to encourage people to live in walkable, transit-accessible inner cities, saving transportation costs and reducing land consumption? Or are we willing to continue the sprawling development of the region into the exurbs, encouraging car use and wasteful land consumption?

There is no formula that can describe the tools Arlington has successfully used to encourage dense development around Metro stations over the past ten years. The existence of Metro itself is not enough to guarantee greater growth in transit-oriented development. Indeed, consider the growth patterns in Northern Virginia between 1990 and 2000 (via The Washington Post):

During that period, as is demonstrated by making a comparison to the map at the top of this article, population increased systematically throughout the region, not just along Metro corridors (though they too saw growth). What was different between the 1990-2000 decade and the 2000-2010 one?

For one, these areas of Northern Virginia — Arlington County, Alexandria, Falls Church, and close-in parts of Fairfax County — were not fully developed in 1990: There were still plenty of building plots open along freeways. That situation largely disappeared over the past ten years, so the only way to build in the close-in suburbs of Washington is now to build up, such as in Arlington.

Perhaps just as important, the financial and political climate in favor of infill development around transit was not as strong during the 1990s as it was during the 2000s. This limited developer interest in investing in new construction around Metro stations. Meanwhile, public agencies did not do enough to increase allowed construction heights and encourage a mix of uses.

Fortunately, on both counts, feelings have changed over the past ten years: There is now a clear public interest in supporting the growth of denser areas and transit has grown in popularity where it has been provided effectively.

In some regions suffering from down economies, good transit and effective planning will not be enough to encourage development such as has occurred in Northern Virginia.

But in places like the Washington region where population growth continues, the data from Census 2010 present compelling evidence for the ability of cities to make decisions about how to grow and alter the regional equation. Arlington’s decision to allow for dense development around Metro stations, developer interest, and a clear demand for the product have provided a strong case for the importance of understanding and taking advantage of the connection between transportation and land use.