Traffic improvements costing from $49 million to $162 million would be needed at seven Northern Virginia sites being considered for a proposed Navy complex, but many of those improvements would be necessary even if the Navy did not move there, according to a government-sponsored environmental report.

Parking would be a huge problem at some sites and, in some cases, new fire stations and recreational areas would be needed, said the report released by the General Services Administration.

At public hearings this year, many Alexandria and Arlington residents expressed deep concern about the Navy project, citing its potential effects on traffic and the environment.

"We never thought it would be easy," Art Turowsky, the GSA project manager for the proposed Navy complex, said yesterday. He added that many of the traffic improvements would be needed to accommodate other development allowed under current zoning laws.

"If not the Navy, it may be someone else," Turowsky said of developing the sites. "It's not all chargeable to the government."

It is not clear who would pay for the traffic improvements related to the Navy project. "Hopefully, there are ways we can deal with the transportation impacts and costs," Turowsky said. "We look to the creativity of the development community to help us all figure it out."

Turowsky said the GSA and Navy would not proceed with plans that are impractical. "We don't want it if it doesn't work either," he said.

The Navy project would consolidate thousands of workers now at 20 locations in Northern Virginia. Congress has authorized $240 million for 1 million square feet of the 2-million-square-foot project, Turowsky said. Plans call for awarding a construction contract next year.

The seven sites under consideration include three in Arlington and four in Alexandria. Six have been proposed by private developers. The seventh is the Army base at Cameron Station.

According to the GSA report, the lowest traffic bill, $49 million, would be if the Navy chose renovated offices in Crystal City. About 16,000 Navy employees already work in Crystal City.

Traffic expenses would be $158 million at a site on Seminary Road in Alexandria's West End; $130 million at a site on Eisenhower Avenue; $120 million at Cameron Station; $75 million at a site near the Van Dorn Street Metro station; and $59 million for a proposal that includes parts of Pentagon City and Crystal City in Arlington.

Traffic expenses would be $162 million at the Port Potomac project proposed by Alexandria 2020 for Arlington rail yard land just south of National Airport.

Denton Kent, executive director of Alexandria 2020, said a second, privately financed study is expected to conclude that the Navy complex alone will not be a significant factor in traffic problems.

"A lot of it is through-traffic," Kent said.

The Charles E. Smith Cos., which has submitted two development proposals in Arlington, also financed the private study. Smith Cos. is the Navy's current Crystal City landlord. Arlington County also participated in the study, which is expected to be released within two weeks.