Proposed changes to the George Washington Memorial Parkway--which some residents fear would turn the scenic roadway into a "commuter speedway"--have received mixed reviews from residents who live along the parkway and those who travel it each day.

The changes, suggested by the Federal Highway Administration to the National Park Service, which owns the road, include a number of controversial proposals to improve safety and the flow of traffic: cutting trees close to the scenic road, adding turnoff lanes at most intersections, installing median strips in several places and putting in one or more traffic lights.

At a public hearing last week, more than 50 people spoke or submitted written comments on the proposed $14 million, three-year improvement project for the parkway's section south of Alexandria. The Park Service is not expected to make any final decisions on the project until the end of the summer. Construction is scheduled to begin in 1984 and, once under way, it will restrict traffic on the 50-year-old parkway for about three years.

The greatest opposition came over a briefly considered (and already rejected) proposal to widen the four-lane parkway to six lanes. Parkway Superintendent John Byrne reassured residents at the meeting that although this idea was discussed last year, it no longer is being considered.

Also considered unlikely to be adopted is the highway administration's recommendation to cut down all trees within 20 feet of the road as a safety measure.

However, Park Service officials said they will endorse an FHA proposal to cut down "the many trees" within five feet of the parkway and numerous other trees "to improve sight lines" for motorists. Byrne said no survey has been done yet to determine just how many trees that would involve.

"Just because there are trees within five feet of the road doesn't mean they are a major safety problem and should be cut down," said Anthony DiStefano, president of the Wellington Heights Citizens Association.

He and other speakers said there would be far fewer accidents on the parkway if the existing 45 mile an hour speed limit were enforced strictly or even lowered.

"The biggest problem is speeding on the parkway, especially during rush hour, with many cars going 10 to 25 miles an hour over the speed limit," DiStefano said. Residents also complained that trucks and commercial vehicles are using the parkway regularly, which is prohibited.

Two nearby residents, Mrs. C. K. Lacy and Priscilla Whitehouse, have urged the Park Service to "raise the speed limit to 50" and build deceleration lanes to permit a faster flow of traffic.

Although one speaker claimed the average speed on the parkway is now 54 miles an hour, Byrne said there have been no recent surveys to gauge traffic speeds and the Park Service does not plan to change the speed limit.

Among the most controversial FHA proposals is one to install as many as three traffic signals on the parkway, including one at Belle Haven Road, the busiest of the 16 parkway intersections south of Alexandria.

Strong opposition to any traffic signals was registered by many of the residents and civic group representatives who spoke or submitted written comments on the proposed changes.

However, Fairfax County Supervisor Sandra Duckworth of Mount Vernon said in a statement read at the meeting that although she "questions signalization, . . . this may be the one place (Belle Haven Road) where it might be necessary." She added that she was concerned that "once we break with the tradition of no signalization and put it in just one place, how long before we would be asked to accept it at other intersections?"

Rep. Stan Parris (R-Va.) said his "top priority is safety" but he is concerned that a traffic signal would significantly "change the character" of the scenic parkway.

Commuters would be the main beneficiaries of both a traffic light and the deceleration or turning lanes proposed at most intersections. Rush-hour traffic constitutes about half of the parkway's total traffic and causes the major congestion at intersections, Park Service officials say.

"Please let's forget about traffic lights," said Harry Lyon, who called himself "an amateur historian of the parkway." He noted that a traffic light was installed on the parkway near National Airport, but it was removed after a rash of accidents there.

Despite the many changes proposed, the FHA concluded that "the Mount Vernon Highway is less accident-prone than most highways."

In the five years from 1975 to 1979, there were 611 accidents with property damage, 197 with injuries and seven fatalities on the southern section of the parkway between Alexandria and Mount Vernon, according to the FHA. The parkway now carries 27,000 cars on an average weekday on this section, its busiest.

The FHA also concluded that the 8.5-mile southern section, virtually unchanged since it was opened in 1932 on the 200th anniversay of George Washington's birth, is still in relatively good condition and should be repaired rather than rebuilt. Rebuilding would cost an estimated $54 million.

The Park Service has indicated it opposes closing Waynewood Boulevard, one FHA alternative for improving that intersection, but has taken no position yet on major intersection changes proposed at Belle Haven Road and Belle View Boulevard.