The effort to protect the city's monuments has begun to encircle the Lincoln Memorial, and the U.S. Commission of Fine Arts votes this week on a seventh attempt to establish balance between post-9/11 security, traffic flow and tourist needs at the storied landmark.

"The truth is, the Lincoln Memorial is probably the most prominent monument as an active forum for the expression of democratic values," said Thomas Luebke, secretary of the U.S. Commission of Fine Arts, in an interview last week. "With all the things that have happened there -- Marian Anderson's performance, Martin Luther King Jr.'s 'I Have a Dream' speech, the AIDS quilt -- it's a very sensitive issue to start talking about barriers in a place like this."

But Sept. 11, 2001, changed sensibilities and procedures, and now the sweep of the grounds is a swirl of dirty orange snow fence and dusty gray Jersey barriers. Thursday, the arts commission is to review the latest incarnation of a proposal for a $15 million project to permanently close the east end of the Lincoln Memorial traffic circle with a row of antiterrorism bollards. The plan is one of dozens of design ideas proposed since officials first began tinkering with the ribbon of traffic gridlock around the circle in 1972.

The circle was created as part of the original memorial's design and included a cobblestone parking pad for the five or so Model Ts that planners in the 1920s envisioned would motor in for a visit.

A half-century later, officials closed the part of the circle in front of the Lincoln to all but foot traffic for the bicentennial celebration in 1976. Since then, tourists have been able to get to the memorial by bus or on foot, in recent years zigzagging through rows of Jersey barriers, temporary sidewalks and security checkpoints.

One part of the protective design, a 30-inch-high, C-shaped granite security wall around the back sides of the memorial, was approved by the National Capital Planning Commission and then the arts commission in late 2003.

Construction began in April 2004, and the work has thrown cars from the Arlington Memorial Bridge and George Washington Memorial Parkway into a maze of snow fencing, detours and gridlock.

Under that plan, there will be new pavement in the traffic circle, and lanes will be reconfigured to accommodate a larger morning rush-hour crowd. There will be two left-turn lanes onto 23rd Street Northwest. And there will be more and clearer signs. The project also will feature more drop-off areas for tour buses, new food and gift kiosks and safer pedestrian and bicycle crossings, said Alexa Viets, the National Park Service's transportation manager for the Mall.

Parks officials expect the roadwork to be completed next summer and work on visitor facilities to continue through 2006.

The road construction and traffic delays caused by the profusion of security measures have drawn grousing from commuters, although National Park Service spokesman Bill Line emphasized that the project is also about security and preservation, rather than simply traffic flow.

"This is a project that has a national, even international icon in the center of it," Line said.

The architectural side of the project has generated little opposition.

The issue of how to close off the mouth of the C-shaped wall -- with something that would keep out bomb-carrying trucks but preserve the famous vista of the Mall, from the reflecting pool to the Capitol, and not interfere with the symbolism of the site -- has been the most controversial part of the design.

"The first preference for the [fine arts] commission is that barriers are simply not there. They are obtrusive and conflict with the ideals of a free and democratic society," Luebke said. "It's a very agonizing process." But with Congress mandating a security plan after the Sept. 11 attacks, the commission has been forced to talk about bollards, fences and walls.

Among rejected proposals were a wall that would have cut across the base of the memorial at the bottom step -- and, critics said, rendered obsolete the image of the memorial printed on the back of every five-dollar bill. Other suggestions that were turned down were a dry moat and a row of stone bollards near the top of the steps that one detractor said "looked like teeth."

"They were talking about these big, concrete things that would look terrible," said Judy Scott Feldman, founder of the National Coalition to Save Our Mall.

Over the past three years, concepts for the final security barrier have moved up and down the various staircases and plazas that lead from Lincoln's feet to the edge of the Reflecting Pool.

Feldman was a vocal critic of a concept approved earlier by the National Capital Planning Commission to place a row of bollards near the base of the bottom step. She called it unfriendly and unsightly.

Stephen Lorenzetti, deputy superintendent of the Mall, avoided the dispute but echoed Feldman's sentiment on that concept. "One of the problems with that plan was that it was considered a little claustrophobic," he said.

This month, the planning commission revised that concept design, opting for a line of dark metal bollards near the Reflecting Pool but far enough from the water for a park maintenance vehicle to pass. That concept is what the fine arts commission votes on this week, and if it gives an expected approval, work will begin on specifics of the design. The two outer edges of the staircase that travel down grassy terraces would be lined with tall hedges that would hide a security cable designed to fill gaps between rows of bollards.

"We'd get the tallest hedges possible," Lorenzetti assured the board, whose members were worried that the growth of the hedge would take years, perhaps even longer than approving a plan is taking.

The view of the Lincoln Memorial from the Arlington Memorial Bridge has undergone radical changes as construction work has been done around the memorial in an effort to protect it from potential acts of terror.