The Height Act, passed by Congress in 1910 in order to protect views of Washington's skyline, limits most developers from building anything higher than 130 feet into the air.

The question for Akridge, the developer planning a mixed-use project atop the railroad tracks behind Union Station, and the D.C. Zoning Commission is where exactly to start counting.

At an auction in 2002, Akridge bought the development rights to 14 acres worth of air rights above the tracks, where it plans to build a 3 million-square-foot mixed-use project that the company envisions as a magnet for companies and residents interested in making rail connections up and down the East Coast.

To support the project, D.C.-based Akridge has proposed building a platform 27 feet above the tracks, the height at which the H Street bridge traversing the area crests and where it will connect to the new development. Akridge interpreted the Height Act to mean that it should start counting the height of the new buildings from that level because H Street NE -- unlike First or Second streets, which are not raised -- directly intersects with its development area.

As a result, Akridge's buildings could rise nearly 160 feet above the railroad tracks. "Here we are at the most intensive transportation infrastructure in the entire mid-Atlantic region, and we clearly want to maximize the use of that infrastructure through the use of smart growth," said David Tuchmann, Akridge vice president of development.

The District's Office of Planning endorsed the idea, proposing a new zoning district for the air rights area in which construction 130 feet above the platform would be allowed but Akridge would have to apply for approval for specific buildings. To enable the new rules, the D.C. Council amended the city's Comprehensive Plan in November to remove language saying that "any building constructed in the air rights should be measured from the existing grade of 1st Street or 2nd Street NE, rather than from the overpass."

Harriet Tregoning, planning director, said the proposal would allow for the development of an extended street grid around buildings of varying sizes and uses rather than a more dense "uni-block" that Akridge could build if it chose to. "This isn't about how to subvert the Height Act, it's about getting the best design we can," she said.

Akridge's taller building designs still require approval from the Zoning Commission and from the Historic Preservation Review Board, and they met some opposition at a Jan. 6 Zoning Commission hearing. Alma Gates, a member of the Committee of 100 on the Federal City, a local coalition, said the plan could "create prominent vertical scars" to the city's sightlines. The National Capital Planning Commission called the proposal "inconsistent" with its interpretation of the Height Act. A number of Zoning Commissioners also raised concerns about the height.

Union Station's Capital Hill neighbors, however, after a dozen meetings with the developer, backed the plan, as did Ward 6 Council member Tommy Wells. "We want to see that the buildings do not overshadow the existing residential properties," neighborhood resident Rob Amos said at the Jan. 6 hearing on behalf of Advisory Neighborhood Commission 6C. "We do not see this project radically altering the vistas of our community."