For years, residents of Old Town Alexandria have complained about the noise and disruption of traffic on U.S. Rte. 1.

About 73,000 cars and trucks a day use the Alexandria portion of Rte. 1, most of them passing through the historic city on their way to other destinations. Local elected officials have long talked of ways to diminish the impact of out-of-town traffic, but only recently have they begun to do anything about it.

In March, the Metropolitan Washington Council of Governments is to complete a study addressing the alternatives that have been proposed for Rte. 1, including relocating the highway and tunneling it underground or even under the Potomac River.

At the same time, however, there is a growing realization that any of the more exotic solutions would be enormously expensive, and that citizen opposition makes relocating the road unlikely.

As a consequence, some officials contend, Alexandria may have to look to simpler answers, such as creating a buffer of commercial enterprises along Rte. 1, setting aside additional capacity for car pools, or even charging tolls.

The city has already started to take steps in that direction.

In January, the city restricted a lane in each direction to cars carrying three or more passengers during rush hours, prompting an outcry from Fairfax County commuters.

More recently, after transportation planners concluded that the car pool lanes were underused, the restriction was relaxed to allow two persons per vehicle, and use of the car pool lanes has surged, officials said.

Long-term solutions will be considerably more complex.

Among the options that are under consideration are building twin, two-lane tunnels under Patrick and Henry streets; tunneling under Fayette Street; building an elevated version of the road that would run parallel the railroad tracks through the city, and tunneling beneath the Potomac River.

"Anything's possible," said Charles Kenyon, director of transportation in Alexandria. "It's not ridiculous to look at any alternative."

Nonetheless, officials concede that some alternatives, such as an elevated highway, would be politically impossible. "It wouldn't just be political suicide, it would be community suicide," said Mayor James P. Moran Jr., adding that he would be "unalterably opposed" to any elevated version of Rte. 1.

"We would never recover our residential character if we did something like that," he said.

Tunneling beneath Old Town, too, poses problems. Any such project would tie up traffic for years and pose a threat to historic properties adjacent to the tunnel, officials said. Moran said he favors tunneling beneath the Potomac, although he acknowledged that "the expense would be enormous."

In the absence of alternatives, Moran said, the city is "going to have to be more restrictive with regard to allowing vehicles through Alexandria."

He added, "Our capacity is finite."