Answer Man Favors Accessorizing the Streets

By John Kelly
Sunday, April 15, 2007

Driving into the District, we noted a curious phenomenon. Road repairmen were pouring concrete as they fixed sidewalks and curbs in Chevy Chase. As we crossed the border into the District of Columbia, a crew was also replacing some lengths of curbing, but with a significant difference. Instead of mundane concrete, they were installing granite segments, cut to size! We realized that all the curbs throughout D.C. are granite. As we had recently upgraded our own kitchen surfaces with granite, at a cost of several thousand dollars, we wondered how the use of such an expensive material can be justified by the city.

-- Tom and Marilyn Marcy, Centreville

When you want to make an impression, use stone. Would the Washington Monument be quite as impressive if it were made of concrete? Would the East Building of the National Gallery of Art look as cool as it does if it were built out of wood?

Washington is set in stone, and the curbs are no different.

In truth, not all the District's curbs are made of granite. It's primarily those curbs on federally aided streets or in historic areas, as stipulated in 1983 by Section 24, Chapter 11, of the D.C. Municipal Regulations. (Some curbs -- in Georgetown, Capitol Hill, Eckington -- are bluestone.)

As you no doubt learned in school, granite is an igneous rock formed by the slow cooling and crystallization of volcanic magma. (Or, as Dr. Evil would say, "magma.") Yes, it's more expensive than concrete -- about $45 per linear foot vs. $25 -- but it's more durable, said Abdullahi Mohamed, a supervisory civil engineer with the D.C. Department of Transportation.

Granite -- solid, heavy -- resists road salt and errant snowplow blades. When there's roadwork to be done, granite curbs can be lifted up, set aside, then put back in place.

The District orders its curbs from the North Carolina Granite Corp., which has the world's largest open-face quarry in Mount Airy, N.C. The granite -- white with flecks of black, giving it a gray appearance -- is called Mount Airy white. It's not as expensive as the granite used in homes because it isn't polished to a glossy finish.

Last week, Answer Man watched as a crew from Capitol Paving of D.C. installed new curbing on Florida Avenue NW. A webbing belt was wrapped around the center of a 9-foot-10-inch-long piece of granite. The sling was attached to the scoop of a Bobcat, which lifted the stone and then lowered it slowly into place. Masons used a string line to make sure the curb was level and then inserted a thin cork joint between the curbs.

As with an iceberg, much of a curb can't be seen. It's 12 inches deep, but only seven inches show aboveground. The workers filled around the curb with dry-mix concrete, then sprinkled it all with water so the curb would set. When they were done, they washed the curb. It gleamed, with an edge you could slice a tomato on.

"It's more beautiful than concrete," Abdullahi said of the granite.

And why shouldn't Washington have attractive curbs? Answer Man thinks that wherever possible we should strive for beauty, even in the lowly and the mundane. After all, Washington is a city of straight lines, from the grid that Pierre L'Enfant drew when he laid out the city to the knife's edge walls of the National Gallery of Art East Building. Granite curbs help to crisply delineate the landscape, separating street from sidewalk and reminding us that it's nice to live in a beautiful city.

Julia Feldmeier helped research this column. Send your Washington-related questions For a video tour of Washington's granite curbs, go to

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