The National Park Service has drawn up a controversial $16.5 million plan aimed at easing traffic bottlenecks on a heavily congested section of the scenic George Washington Memorial Parkway between the Theodore Roosevelt Bridge and Spout Run.

The plan, which has triggered objections from Rep. Frank R. Wolf (R-Va.) and other officials, includes modifications at several key entrances and exits where rush-hour tie-ups frequently occur. It does not provide for additional traffic lanes, a major demand of the plan's critics.

Park Service officials contend that the plan will help relieve backups, reduce traffic accidents, save money and prevent environmental damage to the tree-lined, federally owned parkway that overlooks the Potomac River and Theodore Roosevelt Island, a national wildlife area.

"You've got to protect the park," said John F. Byrne, the parkway's superintendent.

But Wolf denounced the Park Service plan as "totally and completely inadequate." He said the section of four-lane roadway should be widened to at least five and possibly six lanes. Several other Northern Virginia and District officials also suggested additional lanes and other changes.

The 1.6-mile stretch of the parkway, used by thousands of Virginia and Maryland commuters, has been the focus of protracted debate and several studies since the 1950s. Park Service officials said the current review is designed to settle the issue "one way or the other," as one federal planner put it.

The tie-ups on this section of the parkway result largely from a convergence of several arteries, including Spout Run Parkway, along with two major Potomac crossings, the Key and Roosevelt bridges. Weekday traffic at the parkway's juncture with Key Bridge averages 42,000 cars a day, officials said.

The Park Service's preliminary plan is expected to undergo extensive review by other agencies, and officials said it is likely to be revised before a final decision is announced, probably in December. Public hearings on it are scheduled for Oct. 8 in McLean, Oct. 9 in Arlington County and Oct. 10 in the District.

Other sections of the parkway already have undergone repairs as part of a long-range effort to rebuild the road's deteriorating surface and improve congested or hazardous interchanges. The planned overhaul of the stretch near Spout Run will likely be completed by the early 1990s, officials said.

The Park Service proposal, outlined in a draft environmental impact statement scheduled to be published later this month, calls for lengthening the parkway's entrance and exit ramps and lanes near Spout Run Parkway, Key Bridge, Roosevelt Bridge and the Roosevelt Island parking lot.

In addition, the road would be repaved with a form of asphalt designed to reduce skidding in wet weather, officials said. Hundreds of minor accidents and several fatalities have occurred on this part of the parkway in recent years, and officials said the new pavement and other measures would increase safety.

The Park Service turned down other proposals under which the road would be widened to six lanes. Michael W. Donnelly, the agency's regional planning coordinator, said these plans would increase construction expenses to as much as $31.8 million, nearly twice the cost of the Park Service's "preferred alternative."

In addition, Donnelly said, traffic studies indicated that the additional lanes would probably not lead to significantly greater reductions in congestion or accidents as compared with the Park Service's proposal.

To construct the additional lanes, the Park Service would be required to cut down hundreds of oak, maple and other trees, he added. A section of the Potomac River near Key Bridge also might have to be filled in.

Along the parkway near the Roosevelt Island parking lot, Donnelly said, park visitors and motorists would be "looking right at Rosslyn," where high-rise buildings predominate instead of trees. "That's a fairly significant change in parkway character."

Wolf, whose proddings helped spark the Park Service's new study, said he plans to seek changes in the agency's proposal. Describing parkway traffic backups as "horrendous," Wolf called for an additional southbound lane between Spout Run and the Roosevelt Bridge and another northbound lane, at least at key points.

"From an environmental viewpoint, we're not damaging any park land," Wolf said. "That is the gateway to the nation's capital."

Wolf also said he would push for a new exit from the southbound parkway to Rte. 50 (Arlington Boulevard) to improve access to Rosslyn, a new southbound exit to Va. Rte. 110 toward Crystal City, and possible reopening of a parkway ramp to Key Bridge during morning rush hours.

Additional lanes have drawn support from some Arlington and District officials. "I think you would get better traffic flow," said Bill Scruggs, Arlington's chief of traffic engineering. George W. Schoene, D.C. traffic services chief, said another northbound lane would help reduce afternoon rush-hour congestion.

Local officials suggested several other revisions. The Virginia Department of Highways and Transportation urged the Park Service to impose car-pool restrictions on a ramp from the parkway to Roosevelt Bridge. The move would help reduce delays at the bridge for car pools using I-66, officials said.

Some Arlington officials have suggested constructing a new ramp from the southbound parkway to Rosslyn Circle to improve access to Rosslyn and eliminate a bottleneck at Lynn Street.

Nevertheless, the Park Service's plan has gained backing from one motorists' group, the American Automobile Association. "It sounds to me like they're making the best choice," said AAA spokesman Doug Neilson. "If building the additional lane doesn't solve the problem, why spend that money?"