The Arlington County Board has submitted proposals to the National Park Service that board members say should improve safety and protect the sylvan beauty of the George Washington Memorial Parkway between the Roosevelt Bridge and Spout Run Parkway.

The board's action followed a Nov. 19 hearing on four plans the Park Service has proposed to ease rush-hour traffic bottlenecks on that heavily congested stretch of the scenic GW Parkway.

The recommendations adopted by the County Board are a modified version of the $16.5 million plan the Park Service prefers for the 1.6 mile stretch between Spout Run and the Roosevelt Bridge, an area traveled by an average 42,000 cars daily.

Although one of the Park Service proposals would do little more than repave the road network, Mary Margaret Whipple, vice chairman of the County Board, said, "We really felt there was a need for some safety improvements."

Whipple also noted that Arlington's recommendations, which place a heavy emphasis on preserving the environment and developing hiking and biking trails, were adopted last week by the transportation planning board of the Metropolitan Washington Council of Governments.

The work proposed by the Park Service would include lengthening the parkway's exit and entrance ramps and lanes near Spout Run Parkway, Key Bridge, Roosevelt Bridge and the Roosevelt Island parking lot. The proposal also calls for repaving roads with an asphalt designed to reduce skidding in wet weather.

The board deferred action on a plan to place a traffic light at Spout Run Parkway and Lorcom Lane, a proposal vehemently opposed by most area civic associations. The county will inform the Park Service of its position on the light at a later time.

Among the major features of the board's recommendations were:

*Add a third continuous outbound lane from the Key Bridge exit ramp to the Spout Run Parkway entrance. Most of the ramp is already three lanes, so an extension of the third lane directly to Spout Run would involve minimal construction and would avoid the need to cut into and then sharply out of northbound GW Parkway traffic.

Board members said they did not want a third outbound lane from Spout Run to the GW Parkway.

*Add an additional inbound ramp from the GW Parkway to the Roosevelt Bridge that would split to the right onto Rte. 50. This proposal was viewed as a better way to direct traffic into Rosslyn because the board strongly opposes opening the GW Parkway ramp to the Key Bridge during morning rush hour. (The ramp does not open until 9:30 a.m.) Extend the Roosevelt Bridge outbound ramp onto the GW Parkway to provide a longer merge lane. The board did not specify how far the ramp should be extended, but said the current length poses a safety risk because the line of sight is poor for bridge traffic merging onto the parkway.

*Landscaping improvements at Rosslyn Circle to ease left turns from Lynn Street to the GW Parkway and provide a hiking, biking and jogging trail on the south side of Lynn Street approaching Key Bridge.