If the 1791 design of French planner Pierre Charles L'Enfant had been followed to the letter, Pennsylvania Avenue possibly would have developed into one of the world's most attractive boulevards, replete with splendid monuments, parks, fountians and grand vistas.

But L'Enfant's vision of a beautiful tree-lined link between the U.S. Capitol building and the White House never materialized. Instead, Pennsylvania Avenue has become a shabby thoroughfare of decaying buildings and parking lots, with little commercial appeal.

In 10 to 15 years, however under a $130 million redevelopment plan Pennsylvania Avenue is scheduled to at last become the great "ceremonial way" L'Enfant had in mind.

Yesterday John Woodbridge, executive director of the Pennsylvania Avenue Development Corporation, established by Congress in 1972 to redevelop the avenue, took reporters on a brisk walking tour down the avenue. Braving slush and icy temperatures, Woodbridge walked along, pointing out to reporters how the street will be transformed into a bustling "downtown community" of new shops, office buildings and housing.

Major renovations will be made in the street itself under the plan. About seven feet will be lopped off each side making street space more narrow and sidewalks extremely broad.

The street would for the most part be straightened and would extend in a beeline from the U.S. Capitol building to the U.S. Treasury with rows of trees on both sides.

Woodbridge said the outlay of $130 million in federal funds is expected to generate more than $400 million of private investments in new office buildings, shops, and housing.

The development corporation asked Congress for $36 million last year to get the project started, but was turned down. Woodbridge said another request for only $5 million will be made to the new Congress. The money will be used to begin the landscaping projects.

In addition, Woodbridge said, the corporation will ask Congress' approval to borrow about $25 million to acquire property along the redevelopment route.

"Apart of the plan is to simplify the street and make it safer and more attractive for pedestrians," said Woodbridge, as he started the tour at John marshall Place and Pennsylvania Avenue.

"The avenue is right now a no-man's-land for pedestrians because it is so difficult to cross," he said. "We want the avenue sidewalks to be a place where people will want to come and sit under shade trees or eat at a sidewalk restaurant," said Woodbridge.

Under the Plan, said Woodbridge, there will be about 5,000 person who will live along Pennsylvania Avenue in 1,500 units of new apartments and town houses. The downtown residents will in some cases, be able to live, shop and work in the same buildings, he said.

About half of the new housing units will be built on either side of 8th Street, which will be closed to vehicular traffic and developed into a pedestrian mall running from the avenue to the National Art Gallery, he said.

Buildings in the four-block area between 7th and 9th Streets, E Street and Pennsylvania Avenue and along the three blocks of 8th Street will resemble an Italian hill town or Indian cliff-dwelling, Woodbridge said.

Buildings along the avenue will rise 110 feet with an arcade of stores on different levels, office space above the stores and apartments on the top four floors, where residents would have a striking view of the avenue.

Inside the block, town houses would be stepped down in two- to four-story tiers, with open air walkways in between. Beneath the ground would be several levels of parking and storage space.

Other housing units also would be constructed in now vacant spaces along the avenue, using the same scheme to include commercial, office and living space in the same structure, Woodbridge said.

Woodbridge said the Pennsylvania Avenue of the future will be a rich combination of modern buildings and older structures preserved because of their architectural or historic value.

He said the redevelopment plan does not require architectural uniformity in all of the new structures. "We will depend heavily on the beauty of the landscaping of the avenue itself to hold this plan together," said ZWoodbridge.

Everywhere possible existing buildings will be set back 50 feet from the street to help broaden the sidewalk and pedestrian space. The idea, Woodbridge said, is to provide a grand vista from the U.S. Capitol to the White House.

At least three structures that obstruct the ideal view down the avenue - the Evening Star building, the old Post Office, and the Willard Hotel - will be saved.

The plan calls for preservation of the facades of other buildings such as the Apex liquor store building, built in 1888. Litwin's antique store, and the old Matthew Brady photographic studios, where the Mark Weiss Camera Shop now is located. The facades of the older structures would be removed and fitted on to new buildings along the avenue, Woodbridge said.

The most controversial aspect of the Pennsylvania Avenue Plan has surrounded the Willard Hotel, located at 14th Street and Pennsylvania Ave.

The owners of the hotel, which ceased operation in 1968, have filed a suit in the U.S. Court of Claims asking that the U.S. government be made to pay for financial losses caused by various redevelopment plans that interrupted operation of the hotel during past years.

The owners also would like to tear down the deteriorating hotel and use the land for another purpose, but an injunction issued by the U.S. Court of Appeals bars demolition of the building.