Under a Smithsonian Institution proposal granted preliminary approval by a federal design panel, part of Jefferson Drive would be realigned to create more space in front of the Smithsonian Castle, and temporary vehicle barriers would be replaced by permanent obstructions.
A preliminary version of the plan, which aims to improve perimeter security for nine Smithsonian buildings on the Mall, was approved by the National Capital Planning Commission this month. If it is granted final approval, construction probably would begin in two years, Smithsonian officials said.
"Where people would see the greatest change would be in front of the Castle," said David Sousa, program manager for the Smithsonian's Office of Protection Services. "A good portion of the Castle is sitting almost an arm's distance from the road, so we've proposed a little shift of Jefferson Drive where it frames the Castle."
The realignment would shift Jefferson Drive farther into the Mall, creating more space between the road and the Castle. Wide pedestrian paths would lead to a plaza in the newly created space. Approaching from the west, the road would narrow near the Freer Gallery of Art and curve out in front of the Castle. After curving back toward the Arts and Industries Building, the road would widen. Existing parking on that stretch of Jefferson Drive would be removed.
Aside from final design approval from the planning commission, the realignment would require approval from the National Park Service, which oversees the Mall.
Most of the security proposal aims to replace temporary vehicle barriers erected shortly after the Sept. 11, 2001, terrorist attacks with permanent structures designed to protect the buildings from vehicle-carried explosives.
Currently, many of the museums are ringed by empty concrete planters, but those would be replaced by reinforced design elements -- such as hardened benches and low walls -- under the proposal.
"It wouldn't be so that you'd look and see a wall of bollards up and down the street," said J.J. Mclaughlin, director of the Office of Protection Services.
For example, low walls and benches would follow the edge of the existing sidewalk along 14th Street NW and also on Constitution Avenue, and retractable bollards would be installed at employee driveways.
Other buildings in the plan include the National Museum of American History, the National Museum of Natural History, the S. Dillon Ripley Center, the Arthur M. Sackler Gallery of Art, the National Museum of African Art and the Hirshhorn Museum.
The plan was designed to comply with the National Capital Urban Design and Security Plan, a set of guidelines adopted by the planning commission last year to improve the aesthetics of perimeter security throughout the city's core.
The cost of the Smithsonian plan is estimated at $20 million to $30 million but could change as the design is finalized, Sousa said.