The Avenue wasn't quite ready for prime time yesterday, but the ceremony went ahead as planned.

Perched on a platform above the sidewalk directly in front of the White House, first lady Laura Bush declared "a marvelous Pennsylvania Avenue" to be open again for people to enjoy freely.

Conspicuously absent were the 88 elm trees planned by landscape architect Michael Van Valkenburgh as part of his competition-winning design for the 1,600-foot-long stretch of Pennsylvania Avenue between 15th and 17th streets NW.

The trees will be planted come spring, officials said. Nevertheless, they were sorely missed yesterday. Without them, the newly pedestrianized boulevard looked distinctly unmarvelous. It looked, rather, enormously barren and somehow sad.

Also missing were neoclassical guard houses designed by architect Frederick Bland (of the New York firm of Beyer Blinder Belle) for entrances at 15th and 17th streets and Madison and Jackson places NW. Only partially completed, these are surrounded by chain-link fencing.

As a result, an impression of messiness persists despite the fact that the motley assortment of concrete barriers that has marred the place for almost 10 years is gone at last.

So, it is difficult to assess with certainty the new state of affairs on this crucial Washington street. And yet, even in its incomplete state, the new design makes it perfectly clear that an era is over, that things have changed dramatically -- and not for the best.

The new design emphasizes that the days are long gone when this portion of the avenue was an integral part of the city, part of its daily vitality and noise and movement. Today, as you pass through the double rows of ribbed, gray steel bollards that block vehicular traffic at 15th and 17th streets, you become aware right away that you are in a distinct, official compound.

Even though it hardly comes as a surprise -- the street has been closed since May 20, 1995 -- this is a sobering realization. Despite its awful appearance, all that concrete junk that was thrown up looked definitively temporary.

Throughout the design process, D.C. Del. Eleanor Holmes Norton and others insisted that everything in the new design be reversible. And that's the way it worked out. The bollards and gatehouses can be taken down without excessive trouble and expense.

But the place certainly does not have that feel to it. Those handsome new oval bollards, for instance, look decisively permanent.

By dividing the pedestrian boulevard into three distinct zones -- entry courts in the east and west with a public promenade in the middle -- Van Valkenburgh gave the new space something of the dignity it deserves.

The simplicity of those large granite pavers in the east and west entry courts, laid in a grid pattern with a random variation in color from light to dark gray, accentuates the long east-west vista. The slight mounding of the street, true to the avenue's historic profile, adds a subtle note of interest.

But the simplicity of the design in concept and materials, in addition to the absence of trees, also accounts for the overwhelming impression of starkness. Only two major changes were made in Van Valkenburgh's original plan, and both were unfortunate.

Initially, he proposed a separate lane alongside the northern sidewalk, defined by a single row of trees on both sides. This was to accommodate a proposed downtown bus, called the circulator, and also to narrow the wide street by a bit.

This idea fell afoul of reversibility advocates, who probably were right to suspect that, down the pike, erasing a row of nice trees might cause a stink. But nixing the proposal sure did rob the new place of a much-needed touch of human scale.

The other major change was to rule out the fine, gravel-like paving that the landscape architect desired for the all-important middle section of the design. Again, the reasons are understandable. A gravelly surface is hard to plow during snowstorms, explained an official of the National Park Service, and this new pedestrian boulevard definitely must be kept open for presidential access and egress.

And again, the change had a negative effect. Replacing the fine gravel with a brown-tinted, asphalt-like aggregate transforms what might have been immediately understood as a pleasant promenade into what can only be seen as an empty street.

A haunting, edgy quality now dominates this section of Pennsylvania Avenue. It is as if, by intention or accident, we have resurrected a ghostly image of a once-vital street. You can practically hear the honking horns of yesteryear.

Personally, I like the unsentimentality of this effect. This once was a lively vehicular street, the design says, and now it's not. But such realism comes at a price: This stark new place is not terribly welcoming. It's like a memorial to Pennsylvania Avenue.

Things will improve with the trees, of course. In 15 to 20 years, those disease-resistant elms will be high and leafy enough to cast long shadows and provide a sense of scale.

And then, too, people can liven up the place -- and did, yesterday. As soon as the ceremonies were over, families of tourists ambled in and began taking snapshots. The sight made you intensely aware that, one way or another, it sure is good to have the avenue back.

Pennsylvania Avenue's pedestrian plaza officially reopened yesterday. Elms will be planted later.In front of the White House, Pennsylvania Avenue pedestrians, above, can stroll on new granite pavers. At left, steel bollards that can be lowered into the ground block vehicles at 15th and 17th streets.