Terry Holzheimer, economic development director for Arlington, VA, had a clever idea. Usually the density of neighborhoods is measured in residents per acre. But historic neighborhoods and transit oriented development are mixed use, so there may be all sorts of activities that don’t get counted by the usual methods. Why not add residents and jobs together to get a measure of “overall intensity”?
That’s exactly what Holzheimer did in his short paper, Urban Development Intensities in the Washington, DC Metropolitan Area. He looked at overall intensity for historic neighborhoods and for new, transit oriented, mixed use centers. For good measure, he also looked at suburban employment centers, including the so-called edge cities like Tysons Corner.
The unexpected conclusion: Historic neighborhoods are more intense than edge cities.
The areas Holzheimer looked at included:
- Rosslyn, VA — a post-WWII concentration of offices and apartments near downtown DC. Many of its towers are in the 20-30 story range, while its streets tend to be wide and car-oriented (view profile).
- Bethesda, MD — a suburban transit oriented district that has been redeveloped over the past 20 years. It has an equal mix of 2-4 story commercial buildings and 15-20 story towers (view profile).
- Georgetown, DC — a walkable 18th century town that is mostly 3-5 story townhouses, with some detached houses, and some commercial buildings built since the 1970s in the 6-10 story range (view profile).
- Alexandria, VA — a walkable 18th century town that is mostly 2-4 story townhouses
, with some very recent commercial and residential construction in the 6-11 story range (view profile).
- Tysons Corner, VA — the archetypal edge city. Tysons is one of the largest suburban commercial centers in America. It has malls, big-box shopping, towers in the 7-22 story range, and residential complexes in the 3-4 story range. With wide arterials and highways everywhere, Tysons is completely car oriented (view profile).
This table shows a selection of Holzheimer’s numbers:
|Area Name||Acres||Job Density||Population Density||Overall Intensity|
Summarizing these findings, Holzheimer wrote:
One perhaps surprising conclusion that can be reached from the data is that the development intensity of Tysons Corner and its edge city comparables is below that of the two 18th century cities of Georgetown and Alexandria. While both of these older cities have increased their development intensity over the past two hundred years, it has been within generally the same development envelope prescribed by the street grid and height and scale of the original buildings. Furthermore, their street grids have accommodated traffic levels associated with 21st century America. … Georgetown and Alexandria are generally perceived as pedestrian oriented, moderate scale urban places, without significant height. It is worthwhile to note that development intensities of 50 or higher do not need to be uncomfortable environments for walking and can easily accommodate activities of daily living. … with few exceptions, development intensities found today fall far short of the intensity levels of those of the 18th century cities around which Washington was developed. (emphasis added)
That’s surprising and important because it confounds popular assumptions. Historic 18th century towns are seen as quaint, sleepy and obsolete. Suburban edge cities, with their jammed highways and tall towers, are seen as dynamic activity centers.
When one compares the actual land use intensity of both patterns, however, the 18th century pattern comes out ahead.
Downtown Washington is easily the most intense area in the region. It’s also extremely diverse in urban design. Under the citywide 12-story height limit, DC encompasses post-WWII and contemporary office blocks, apartment towers, government districts, museum/civic districts, and historic districts. The analysis could be extended by breaking out specific neighborhoods. In particular, how do the historic neighborhoods stack up?
Some of DC’s most walkable historic neighborhoods are:
- Dupont Circle — Built from the 1870s to the early 20th century, the brick townhouses are 3-4 stories, apartments and office buildings range from 3-7 stories, and there are a few newer 9-12 story buildings (view profile).
- Adams Morgan / Kalorama — Built during the first few decades of the 20th century, its large townhouses are 3-4 stories. Apartment buildings are in the 6-8 story range, with a few at 10-12 stories (view profile).
- U Street / Logan Circle — Built in the decades following the Civil War through the early 20th century, the neighborhood is mostly 2-3 story townhouses, with some 6-8 story buildings being built on the avenues (view profile).
- Capitol Hill — Began to be developed in the 1790s with construction continuing throughout the 19th century. Almost entirely 2-3 story townhouses with some 3-5 story commercial buildings (view profile).
This table shows Aurbach’s numbers:
|Area Name||Acres||Job Density||Population Density||Overall Intensity|
|Adams Morgan / Kalorama||221||28.3||47.9||76.2|
|U Street / Logan Circle||337||19.6||37.5||57.1|
Overall intensity spans the gamut, but even quiet, mostly 2-3 story Capitol Hill rivals Tysons Corner. Dupont Circle rivals the DC region’s newer, taller transit-oriented developments for overall intensity. For example, Crystal City, VA has an overall intensity of 109.0 and Ballston, VA has an overall intensity of 97.4.
Historic neighborhoods continue to provide viable models for comfortable, attractive and walkable density. The high-performance design and planning techniques employed by these neighborhoods are well worth studying.
All table figures are derived from Metropolitan Washington Council of Governments estimates for 2005.
Dupont Circle bounded by Massachusetts Avenue, Florida Avenue and 16th Street. TAZ 46, 47, 48 and 49.
Adams Morgan / Kalorama bounded by Connecticut Avenue, Calvert Street & Columbia Road on the north, 16th Street and Florida Avenue. TAZ 114, 115 and 116.
U Street / Logan Circle bounded by Florida Avenue, 7th Street, P Street and 16th Street. TAZ 52, 53 and 54.
Capitol Hill bounded by 4th Street, F Street NE, 11th Street and I-295. TAZ 149, 150, 162, 163, 177 and 178.
Deriving Urban Density and Intensity in Greater Washington, D.C. — A PLANetizen article by Terry Holzheimer, based on the paper referenced above
Arlington Economic Development — A department of the Arlington County government
Metropolitan Washington Council of Governments — population and employment forecasts and related maps
The Garreau Group — Inventor of the term “edge city”
Description of Tysons Corner by the Fairfax County Economic Development Authority
National Park Service — Washington DC Historic Districts
Delightful Density by Laurence Aurbach — More on the topic of historic neighborhoods and their densities.
I am an urban designer working for MNCPPC in Silver Spring. I am working on an urban design study for Downtown Silver Spring. I am looking for population densities of cities, in particular parts or neighborhoods of those cities in order to make logical comparisons. Do you know if neighborhood data of that nature exists for US cities? the census data I have found tends to be for whole city, which I cannot reasonably extrapolate to specific neighborhoods.
The MWCOG forecasts that I referenced above have residential and employment densities by traffic analysis zone (TAZ). Some metropolitan planning organizations in other regions publish similar numbers; you’ll have to check with the MPOs of the regions you are concerned with.
The Census Bureau has residential densities from the 2000 Census for geographic units as small as blocks. The American Fact Finder interface provides quick access to density statistics at the census tract level. Go to this page and select “County” for the geographic type and “census tract” for the table format. On the next page, select the “Population, Housing Units, Area and Density 2000” table.
The simplest interface, however, is gCensus, a Google mashup that provides direct readouts of residential density info down to the block level.
See also the post Fun with Density and Transit Statistics for more discussion of density and how it can be measured.