Cyclists who are adventurous enough to try the District's 14-mile "Interim Anacostia Riverwalk Trail" need to understand two things: Much of the route is on blighted or noisy industrial streets, with actual trail construction still months or years away. And the Anacostia River itself is often out of view.

If you don't mind that, or scary bridge crossings, then the bicycle route is a great way to see little-known parts of the nation's capital, from the industrial to the historic to the serene.

There is a vast concrete dump and a gravel plant and a dormant oil transfer station. There are glimpses of Fort McNair, with picturesque antebellum homes where high-ranking Army officials reside. There are sleepy old marinas, new riverfront playgrounds and picnic areas, wetland restoration gardens and an open-air roller-skating pavilion. From the shaky span of the rusting, aging Frederick Douglass Memorial Bridge, a cyclist can get sweeping views of the proposed Major League Baseball stadium site, and of a large osprey nest.

The route, assembled last year by the D.C. Department of Transportation, is a precursor to a planned 17-mile river trail that mostly will hug the river's banks and is a key component of the District's ambitious plan to redevelop the Anacostia waterfront.

But unlike much of the proposed waterfront development, which will take decades and cost billions, the trail is already under construction, and $9.5 million of the estimated $20 million public cost has been allocated. (Private waterfront developers will pay for portions of the trail on their land.) Large stretches are slated for construction in 2005 and 2006, and city officials say they are seeking federal transportation money to cover the remaining costs.

In the meantime, cyclists must follow the diamond-shaped trail signs that are posted along streets and sidewalks. About 45 signs were installed last year; an additional two dozen or so were put in during the last two weeks, after the city received inquiries about the route from The Washington Post.

Because the word "interim" is printed in much smaller type than "Anacostia Riverwalk Trail," the signs imply that a usable trail is somewhere nearby. For the most part, that is not the case. The signs instead identify a street route.

"We were just trying to get a marker down, trying to build momentum," said Dan Tangherlini, director of the city's Department of Transportation. "You could say there's no trail, and therefore there should be no sign. Or, you can put a sign in as kind of a marker, and show people . . . a route they can take."

Construction of the permanent trail began in June 2003 with the repaving of a deteriorated path through quiet River Terrace Park, just east of the river and south of the Benning Road bridge. It continued with creation of three small stretches of demonstration trail along city-controlled land on the west side of the river, and the repair last spring of a stretch of trail from just under the Douglass Bridge down South Capitol Street to Bolling Air Force Base. At the same time, the District designed the interim route.

"What's really amazing is how much exists in some form or fashion," Tangherlini said. "And then there are some big, gaping disconnects."

Tangherlini led me on a tour of the bike route on a balmy day last week. We began and ended at a trail sign near the Maine Avenue Fish Wharf on the Southwest waterfront, in the 1000 block of Water Street SW. The wharf -- which is slated for a face-lift and expansion as part of the waterfront redevelopment -- has no place to sit and is decidedly utilitarian. But it offers decent seafood and fried fish sandwiches after a ride.

When the bulky restaurants that now line the Southwest waterfront are redeveloped over the next few years, the riverfront promenade will be expanded and improved to include a bicycle path. We had to use Water Street, which had little vehicular traffic but also few opportunities to see the water.

Cyclists can access the promenade at the Police and Fire Pier, and we enjoyed a few pleasant minutes of riverfront riding, with views of the smooth water, the Titanic Memorial at Fourth and P, and the green lawns of the Army's Fort McNair. The historic base -- built where the Lincoln conspirators were hanged in 1865 -- is closed to the public.

So we swung east along P Street, and then south on Second Street SW. To our left, the industrial section of the tour was unfolding: a field of Pepco generators, and the sand, gravel and concrete facilities of Buzzard Point beyond. I could hear the buzzing, grinding and clanking of heavy machinery, and smell the tar and the asphalt and the concrete. We turned left when the road ended at V Street, after catching a glimpse of Fort McNair's 96-year-old Roosevelt Hall, where the vaunted National War College is partially housed.

Just beyond the heavily guarded U.S. Coast Guard headquarters and a defunct art deco-style Pepco plant that seems to cry out to be adapted for reuse, a glimpse of the future beckoned. Here was the first of the three demonstration trails built by the Earth Conservation Corps, a nonprofit group that puts unskilled young adults to work restoring the river and its banks.

The crushed-gravel trail winds past a refurbished pump house that is now the Matthew Henson Environmental Center, through newly planted grass and trees where, a few years ago, there were abandoned vehicles and concrete 25 inches thick.

"The river was always a place where you dumped things in this part of town," Earth Conservation Corps Chairman Robert Nixon told me on an earlier visit. Now, at least in this spot, it was pleasant. Birds chirped and yellow leaves lined the path. From the trees growing at the river's edge, branches drooped gracefully into the water.

The trail winds around an old FBI office building that is being renovated by developer Douglas Jemal before abruptly ending at a gravel transfer station that marked our return to reality.

We retraced our path back to the street and up Half Street SW, past the bulldozers and dump trucks working at the asphalt dump. The smell and the noise were jarring. And the view was surprising. Beyond the peaked gray roof that houses the Department of Public Works's salt supply, there was the shimmering U.S. Capitol dome.

The industrial tour continued under the Douglass Bridge into the city's Southeast quadrant, then up First Street SE. We stopped briefly at the second Earth Conservation Corps demonstration site, which includes another restored pump house, this one located in the river itself, with a gangplank leading from it to dry land.

Standing on the gangplank, I could see the waterfront -- and the challenge of the river trail -- spread out before me. The two demonstration trails, and a third, near the 11th Street bridge, are interspersed among a half-dozen sites, most of them industrial: the gravel transfer station, dormant oil tanks, a police department helipad, the Florida Rock gravel company, a D.C. Water and Sewer Authority storage lot and pump house, the long-vacant Southeast Federal Center and the Washington Navy Yard.

The idea of threading a bicycle path along these mostly gritty areas seemed, at first glance, ridiculous. But it turns out that some of it is already in the works.

The Navy Yard plans to open its six-block riverfront, which includes a cycling and pedestrian trail, to the public next spring when it finishes building a fence to separate the area from high-security military buildings. Next door, the federal center site is filled with cranes building a new headquarters for the U.S. Department of Transportation. The development will include a three-block continuation of the Navy Yard's promenade.

Tangherlini's agency is working with the sewer authority to relocate the vehicles stored next to the pump house, where the city's planning office wants to build a riverfront park and trail. That would extend the path to the land owned by Florida Rock, which has proposed redeveloping its site into a mix of housing, retail and offices -- plans that, to win zoning approval from the District, were crafted to include a river trail.

On the same day as our ride, transportation staffers were meeting with D.C. police to talk about relocating the helipad. Discussions of how to relocate the dormant oil tanks and the gravel transfer stations have also been launched, but remain in preliminary stages.

"That's what we're pushing for here," Tangherlini said, "is trying, bit by bit, to link it all together."

For now, riders must bike up First Street and turn right on M, passing the federal center and Navy Yard on the right and the mostly vacant Arthur Capper/Carrollsburg public housing complex -- soon to be rebuilt with both public and market-rate housing -- on the left. The retail strip on Eighth Street SE, known as Barracks Row because it is across from the Marine Barracks, offers a bike shop as well as interesting cafes and stores -- amenities you won't encounter for the rest of the ride.

At 11th Street SE, we turned right and back down toward the river, finding ourselves suddenly on a stretch of Water Street, then M Street, that was country-road quiet, with pleasant river views, including small marinas dating back to the early 20th century, and a canopy of changing leaves overhead.

But this bucolic moment, too, was quickly interrupted, as the trail ended at the CSX railroad tracks. A crossing planned for construction this spring will link riders to the little-traveled access road that circles behind Robert F. Kennedy Memorial Stadium. But we had to turn back to 11th Street, then travel a nondescript section of K Street to busy Barney Circle to the stadium road.

Again, all was pleasant and quiet for a few minutes until we hit Benning Road NE, a busy city street that crosses the river just below a bridge crossing for trains from Metro's Red Line. Another quiet zone awaited on the river's eastern side: River Terrace Park, with views of the river to the right and, to the left, playgrounds and modest row houses facing the water's edge.

We rode through flocks of Canada geese and merged onto an access road that leads into Anacostia Park. At one point, we hit our brakes to let a furry black caterpillar amble past. I watched a bright red cardinal flit in and out of trees.

Eventually, the trail will continue all the way to the end of the park at South Capitol Street, with a pedestrian and bicycle bridge spanning the railroad tracks on this side of the river. For now, however, D.C. officials say riders should cross back west of the river at the Whitney Young Bridge, then retrace the access road from RFK stadium to Barney Circle. From there they should cross east again, this time over the Sousa Bridge, to a pleasant portion of Anacostia Drive that passes the Anacostia Pool and Recreation Center as well as more playgrounds, athletic courts and fields. A recently repaved path leads up to the Douglass Bridge at South Capitol Street.

Crossing the bridge is dramatic, to say the least. The narrow sidewalk vibrated with the pounding traffic speeding by just a couple of feet to our right. The barrier, while adequate, was hardly reassuring.

But there's a great view of the osprey nest, for those brave enough to look. And as we descended the bridge on the west side of the river, the proposed stadium site came into full view.

Just before the bridge crossing, we met Bill McDonnell -- the only cyclist we saw during our 31/2-hour tour, save for an older man on a wobbly 10-speed going the other way on the Benning Road bridge. McDonnell, of Leesburg, works at the Anacostia Naval Station and is an avid cyclist who rides to Hains Point and back at lunchtime and sometimes makes the 100-mile round trip to and from work.

"I've seen the signs," he told Tangherlini, after we introduced ourselves. "It would be great if this connected to something. A trail along here would be a real plus for the city."

Above, an "interim" version of what city officials hope will be a 17-mile trail along the Potomac and Anacostia rivers winds through River Terrace Park, just east of the Anacostia and south of the Benning Road bridge. At left, city Transportation Director Dan Tangherlini talks with Earth Conservation Corps workers Charles Powe, left, and Henry Wood, right. Washington Post reporter Debbi Wilgoren and Transportation Director Dan Tangherlini ride on Half Street SW, against a backdrop of concrete-mixer trucks.